Whole house particle removal and clean air delivery rates for in-duct and portable ventilation systems.

Science.gov (United States)

Macintosh, David L; Myatt, Theodore A; Ludwig, Jerry F; Baker, Brian J; Suh, Helen H; Spengler, John D

2008-11-01

A novel method for determining whole house particle removal and clean air delivery rates attributable to central and portable ventilation/air cleaning systems is described. The method is used to characterize total and air-cleaner-specific particle removal rates during operation of four in-duct air cleaners and two portable air-cleaning devices in a fully instrumented test home. Operation of in-duct and portable air cleaners typically increased particle removal rates over the baseline rates determined in the absence of operating a central fan or an indoor air cleaner. Removal rates of 0.3- to 0.5-microm particles ranged from 1.5 hr(-1) during operation of an in-duct, 5-in. pleated media filter to 7.2 hr(-1) for an in-duct electrostatic air cleaner in comparison to a baseline rate of 0 hr(-1) when the air handler was operating without a filter. Removal rates for total particulate matter less than 2.5 microm in aerodynamic diameter (PM2.5) mass concentrations were 0.5 hr(-1) under baseline conditions, 0.5 hr(-1) during operation of three portable ionic air cleaners, 1 hr(-1) for an in-duct 1-in. media filter, 2.4 hr(-1) for a single high-efficiency particle arrestance (HEPA) portable air cleaner, 4.6 hr(-1) for an in-duct 5-in. media filter, 4.7 hr(-1) during operation of five portable HEPA filters, 6.1 hr(-1) for a conventional in-duct electronic air cleaner, and 7.5 hr(-1) for a high efficiency in-duct electrostatic air cleaner. Corresponding whole house clean air delivery rates for PM2.5 attributable to the air cleaner independent of losses within the central ventilation system ranged from 2 m3/min for the conventional media filter to 32 m3/min for the high efficiency in-duct electrostatic device. Except for the portable ionic air cleaner, the devices considered here increased particle removal indoors over baseline deposition rates.

Ventilating Air-Conditioner

Science.gov (United States)

Dinh, Khanh

1994-01-01

Air-conditioner provides ventilation designed to be used alone or incorporated into cooling or heating system operates efficiently only by recirculating stale air within building. Energy needed to operate overall ventilating cooling or heating system slightly greater than operating nonventilating cooling or heating system. Helps to preserve energy efficiency while satisfying need for increased forced ventilation to prevent accumulation of undesired gases like radon and formaldehyde. Provides fresh treated air to variety of confined spaces: hospital surgeries, laboratories, clean rooms, and printing shops and other places where solvents used. In mobile homes and portable classrooms, eliminates irritant chemicals exuded by carpets, panels, and other materials, ensuring healthy indoor environment for occupants.

Ventilation and air-conditioning system for PWR nuclear power plant

International Nuclear Information System (INIS)

Ohmoto, Kenji

1987-01-01

This report outlines the ventilation and air conditioning facilities for PWR nuclear power plant as well as design re-evaluation and optimization of ventilation and air-conditioning. The primary PWR installations are generally housed in the nuclear reactor building, auxiliary buildings and control building, which are equipped with their own ventilation and air-conditioning systems to serve for their specific purposes. A ventilation/air-conditioning system should be able to work effectively not only for maintaining the ordinary reactor operation but also for controlling the environmental temperature in the event of an accident. Designing of a ventilation/air-conditioning system relied on empirical data in the past, but currently it is performed based on information obtained from various analyses to optimize the system configuration and ventilation capacity. Design re-evaluation of ventilation/air-conditioning systems are conducted widely in various areas, aiming at the integration of safety systems, optimum combination of air-cooling and water-cooling systems, and optimization of the ventilation rate for controlling the concentrations of radioactive substances in the atmosphere in the facilities. It is pointed out that performance evaluation of ventilation/air-conditioning systems, which has been conducted rather macroscopically, should be carried out more in detal in the future to determine optimum air streams and temperature distribution. (Nogami, K.)

Novel approach for evaluation of air change rate in naturally ventilated occupied spaces based on metabolic CO2 time variation

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Markov, Detelin G.

2014-01-01

IAQ in many residential buildings relies on non-organized natural ventilation. Accurate evaluation of air change rate (ACR) in this situation is difficult due to the nature of the phenomenon - intermittent infiltration-exfiltration periods of mass exchange between the room air and the outdoor air...... at low rate. This paper describes a new approach for ACR evaluation in naturally ventilated occupied spaces. Actual metabolic CO2 time variation record in an interval of time is compared with the computed variation of metabolic CO2 for the same time interval under reference conditions: sleeping occupants...

Emission of formaldehyde by particleboard : effect of ventilation rate and loading on air-contamination levels

Science.gov (United States)

George E. Myers; Muneo Nagaoka

1981-01-01

Dynamic tests for determining the formaldehyde emission behavior of UF-bonded boards involve the measurement of formaldehyde concentration in the air within a vessel which contains a specified board loading L (m2 of board area per m3 of vessel free volume) and is being ventilated at a specified air exchange rate N (hr.-1). Such tests constitute a primary...

Ventilation air conditioner for a reactor container

International Nuclear Information System (INIS)

Ikegame, Noboru; Nakagawa, Takeshi.

1980-01-01

Purpose: To suppress the variations in the internal pressure of a reactor container and smoothly ventilate the reactor container. Constitution: The air conditioner provides an air-flow-rate-control damper, a purge-air supply fan, and a filter device in the air-supply pipe of a reactor container. Furthermore, it provides a pressure difference detector at a part of the container. The air-flow-rate-control damper is connected electrically through a position-modulator-comparison amplifier to the pressure difference detector. When the filtration becomes insufficient by clogging of the filter device and the internal pressure increased abruptly in the container, the pressure-difference detector can detect it, and the damper is operated by a pressure regulator and the comparator so as to control the air flow to the container. Thus, the internal pressure variation is controlled so as to easily ventilate the container. (J.P.N.)

A Technical Basis for Employing Facility Ventilation Air Exchange Rates in the Decision to Downpost

CERN Document Server

Mantooth, D S

2001-01-01

Utilizing the ventilation exchange rate as a basis for the decision to downpost a location within a facility from an airborne radiation area (ARA) based on initial air count(DAC). Not used in the case of a confirmed or suspected contamination release.

Experimental evaluation of air distribution in mechanically ventilated residential rooms

DEFF Research Database (Denmark)

Tomasi, R.; Krajčík, M.; Simone, A.

2013-01-01

The effect of low ventilation rates (1 or 0.5 air change per hour) on thermal comfort and ventilation effectiveness was experimentally studied in a simulated residential room equipped with radiant floor heating/cooling and mixing ventilation systems. The tests were performed for various positions...... of supply and extract air terminals and different winter and summer boundary conditions. Vertical air temperature, operative temperature and air velocity profiles were measured in different positions in the room, and equivalent temperatures were derived, in order to characterize thermal comfort. Contaminant...... with unconditioned outdoor air supply, i.e. at the supply air temperatures higher than the room air temperature. Moreover, low floor temperatures were needed to maintain the desired reference temperature in the stratified thermal environment. Mainly in cooling conditions the ventilation effectiveness depended...

Air quality Performance of Ductless Personalized Ventilation in Conjunction with Displacement Ventilation: Impact of Walking Person

DEFF Research Database (Denmark)

Bolashikov, Zhecho Dimitrov; Lu, Pengfei; Melikov, Arsen Krikor

2015-01-01

The present experiment evaluates the impact of air disturbances from a walking person on inhaled air by ductless personalized ventilation (DPV) with displacement ventilation (DV), when a seated occupant is the source of pollution: bio-effluents and exhaled air. The measurements took place in a full...... and the DV supply. Pollution from feet and exhaled air by one manikin was simulated with tracer gases. Room temperature of 26 °C and 90 L/s DV supply flow rate were kept constant. Measurements under numerous combinations of DPV operation modes and supply flow rates were performed. Tracer gas concentrations...

Assessment of ventilation efficiency for the study of indoor air quality; Appreciation de l'efficacite de la ventilation pour l'etude de la qualite de l'air interieur

Energy Technology Data Exchange (ETDEWEB)

Akoua, A.A.

2004-10-15

An efficient ventilation system provides a good indoor air quality by eliminating air pollutants and ensuring a satisfactory air renewal. Unlike most research works that deal with test cells with controlled boundary conditions, our study focuses on ventilation efficiency in a real environment. In situ experiments are performed and provide the boundary conditions necessary for CFD (Computational Fluid Dynamics) computations. Using CFD for predicting indoor air quality in a real environment is thus analyzed. The influence of permeability on numerical predictions quality is shown. Unfortunately, it is difficult to quantify accurately the air leakages and their airflow rates. Our study proposes a simplified model that includes air infiltration rates in the CFD computations, and that yields satisfactory results. A critical analysis of ventilation efficiency indices is then performed. It is shown that it is currently impossible to evaluate the air change efficiency ( a e ) in an occupied zone. Concerning the air pollutants removal effectiveness, it is shown that the usual index C e is not suited to ventilation systems with variable airflow rates. For such cases, a new formulation of this index is given. The ratio between the airflow rate and the nominal airflow rate of the ventilation system is also taken into consideration. A coupled analysis of this new index and of this airflow rate ratio enables us to assess the air pollutants removal effectiveness while considering the energetic cost of ventilation. We finally show that there is no universal index. The choice of the index depends on the pollutant, on the pollutant concentration, and on the airflow rate. A tool of decision-making aid is thus proposed in order to evaluate the air pollutants removal effectiveness for various ventilation systems. This tool is flexible and rather simple to use. (author)

Practical guidebook on the modulation of ventilation flow rates; Guide pratique sur la modulation des debits de ventilation

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-07-01

The modulation of ventilation flow rates aims at adapting the flow rate of ventilation systems to the real occupancy of rooms, at maintaining a good indoor air quality and at mastering the energy expenses due to air renewing in rooms. This technical guidebook presents the design of modulated ventilation systems (definition of occupancy areas in buildings, choice of presence sensors (CO{sub 2}, hygrometry, temperature, CO, VOC and other specific probes)), their principle and implementation. (J.S.)

Final Report Balancing energy conservation and occupant needs in ventilation rate standards for Big Box stores in California. Predicted indoor air quality and energy consumption using a matrix of ventilation scenarios

Energy Technology Data Exchange (ETDEWEB)

Apte, Michael G. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Mendell, Mark J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sohn, Michael D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Dutton, Spencer M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Berkeley, Pam M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Spears, Michael [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2011-02-01

Through mass-balance modeling of various ventilation scenarios that might satisfy the ASHRAE 62.1 Indoor Air Quality (IAQ) Procedure, we estimate indoor concentrations of contaminants of concern (COCs) in California “big box” stores, compare estimates to available thresholds, and for selected scenarios estimate differences in energy consumption. Findings are intended to inform decisions on adding performance-based approaches to ventilation rate (VR) standards for commercial buildings. Using multi-zone mass-balance models and available contaminant source rates, we estimated concentrations of 34 COCs for multiple ventilation scenarios: VRmin (0.04 cfm/ft2 ), VRmax (0.24 cfm/ft2 ), and VRmid (0.14 cfm/ft2 ). We compared COC concentrations with available health, olfactory, and irritant thresholds. We estimated building energy consumption at different VRs using a previously developed EnergyPlus model. VRmax did control all contaminants adequately, but VRmin did not, and VRmid did so only marginally. Air cleaning and local ventilation near strong sources both showed promise. Higher VRs increased indoor concentrations of outdoor air pollutants. Lowering VRs in big box stores in California from VRmax to VRmid would reduce total energy use by an estimated 6.6% and energy costs by 2.5%. Reducing the required VRs in California’s big box stores could reduce energy use and costs, but poses challenges for health and comfort of occupants. Source removal, air cleaning, and local ventilation may be needed at reduced VRs, and even at current recommended VRs. Also, alternative ventilation strategies taking climate and season into account in ventilation schedules may provide greater energy cost savings than constant ventilation rates, while improving IAQ.

The Contaminant Distribution in a Ventilated Room with Different Air Terminal Devices

DEFF Research Database (Denmark)

Heiselberg, Per; Nielsen, Peter V.

The room ventilation is investigated for three different air terminal devices under isothermal conditions. Velocity distribution in the occupied zone is measured for each air terminal device at different air exchange rates. The maximum air exchange rate is determined on the base of both the throw...... of the jets and the comfort requirements applied to measured air velocities in the occupied zone. Normalized concentration distribution in the test room is determined along a vertical line through the middle of the room as a function of the air exchange rate and the density of the tracer gas. The relative...... ventilation efficiency, , based on the room average concentration is also determined as a function of the air exchange rate and the density of the tracer gas. The influence from the position of the return opening on the relative ventilation efficiency is found for one air terminal device....

Short-term airing by natural ventilation

DEFF Research Database (Denmark)

Perino, Marco; Heiselberg, Per

2009-01-01

The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. This kind of system frequently integrates traditio......The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. This kind of system frequently integrates...... traditional mechanical ventilation components with natural ventilation devices, such as motorized windows and louvers. Among the various ventilation strategies that are currently available, buoyancy driven single-sided natural ventilation has proved to be very effective and can provide high air change rates...... that was aimed at developing and validating numerical models for the analysis of buoyancy driven single-sided natural ventilation systems. Once validated, these models can be used to optimize control strategies in order to achieve satisfactory indoor comfort conditions and IAQ....

Effect of using low-polluting building materials and increasing ventilation on perceived indoor air quality

Energy Technology Data Exchange (ETDEWEB)

Wargocki, P.; Zuczek, P. (International Centre for Indoor Environment and Energy, Dept. of Mechanical Engineering, DTU, Kgs. Lyngby (DK)); Knudsen, Henrik N. (Danish Building Research Institute, Aalborg Univ., Hoersholm (DK))

2007-07-01

The potential of improving perceived air quality indoors was quantified when low-polluting materials are used and when building ventilation is increased. This was done by studying the relationships between ventilation rate and the perceived indoor air quality. A sensory panel assessed the air quality in test rooms ventilated with realistic outdoor air supply rates, where combinations of high- and low-polluting wall, floor and ceiling materials were set up. These materials were ranked as high- and low-polluting using sensory assessments of air quality in small-scale glass chambers, where they were tested individually. Substituting materials ranked as high-polluting with materials ranked as lower-polluting improved the perceived air quality in the test rooms. This improvement was greater than what was achieved by a realistic increase of the ventilation rate in the test rooms. Thus reducing pollution emitted from building materials that affects the perceived air quality has a considerable potential of limiting the energy for ventilation without compromising indoor air quality. (au)

Cost-benefit analysis of decreased ventilation rates and radon exhalation from building materials

International Nuclear Information System (INIS)

Ericson, S.O.

1984-01-01

Decreased ventilation, achieved by weather stripping and other tightening measures, is the most cost effective way to energy conservation. A very low investment can result in a considerable decrease in ventilation rate. For a typical detached house in Sweden this can be equivalent to a decrease in oil consumption of 0.5 m 3 . At present price this corresponds to a saving of SEK 1200, 150 US dollars per annum. The contribution of the building materials to the concentration of radon in indoor air is approximately the inverse to air exchange rate. For a small change in ventilation rate and cost, in SEK/man Sv or US dollar/man Sv, is a function of ventilation rate, exhalation from building materials, the ratio between surface of walls, floor and ceiling to the volume of air. Thus, it is possible to find the specific ventilation rate where the marginal cost for a small increase in ventilation rate and the marginal reduction in radon concentration will give a specific amount of money for each man Sv. Examples are given. Conclusions are that for most building materials in a climate like the Swedish, there are other factors than exhalation of radon from building materials that sets the lower limit of recommendable ventilation rate. (Author)

Short-term airing by natural ventilation - implication on IAQ and thermal comfort.

Science.gov (United States)

Heiselberg, P; Perino, M

2010-04-01

The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. Among the available ventilation strategies that are currently available, buoyancy driven, single-sided natural ventilation has proved to be very effective and can provide high air change rates for temperature and Indoor Air Quality (IAQ) control. However, to promote a wider distribution of these systems an improvement in the knowledge of their working principles is necessary. The present study analyses and presents the results of an experimental evaluation of airing performance in terms of ventilation characteristics, IAQ and thermal comfort. It includes investigations of the consequences of opening time, opening frequency, opening area and expected airflow rate, ventilation efficiency, thermal comfort and dynamic temperature conditions. A suitable laboratory test rig was developed to perform extensive experimental analyses of the phenomenon under controlled and repeatable conditions. The results showed that short-term window airing is very effective and can provide both acceptable IAQ and thermal comfort conditions in buildings. Practical Implications This study gives the necessary background and in-depth knowledge of the performance of window airing by single-sided natural ventilation necessary for the development of control strategies for window airing (length of opening period and opening frequency) for optimum IAQ and thermal comfort in naturally ventilated buildings.

Air ventilation/controlling facility

Energy Technology Data Exchange (ETDEWEB)

Yoshikawa, Kazuhiro; Kinoshita, Shoichiro

1997-12-12

When all electricity supply from the outside of a power plant are lost, a power generator directly connected to an emergency steam turbine which is driven by steams introduced from a nuclear reactor is driven to supply electricity required in the power plant. Cool water prepared by a refrigerator is used as cooling water in an air ventilation/controlling facility of a room equipped with the power generating facility. As the refrigerator, a refrigerator of an existent emergency air cooling water system for an auxiliary air ventilation/controlling equipment is used. This can extend the period of time till the temperature of the room where the power generator is disposed exceeds the temperature range capable of keeping the integrity of the power generator even when all the AC power supply are lost to inactivate the function of the air ventilation/controlling system. (I.S.)

Waste tank ventilation rates measured with a tracer gas method

International Nuclear Information System (INIS)

Huckaby, J.L.; Evans, J.C.; Sklarew, D.S.; Mitroshkov, A.V.

1998-08-01

Passive ventilation with the atmosphere is used to prevent accumulation of waste gases and vapors in the headspaces of 132 of the 177 high-level radioactive waste Tanks at the Hanford Site in Southeastern Washington State. Measurements of the passive ventilation rates are needed for the resolution of two key safety issues associated with the rates of flammable gas production and accumulation and the rates at which organic salt-nitrate salt mixtures dry out. Direct measurement of passive ventilation rates using mass flow meters is not feasible because ventilation occurs va multiple pathways to the atmosphere (i.e., via the filtered breather riser and unsealed tank risers and pits), as well as via underground connections to other tanks, junction boxes, and inactive ventilation systems. The tracer gas method discussed in this report provides a direct measurement of the rate at which gases are removed by ventilation and an indirect measurement of the ventilation rate. The tracer gas behaves as a surrogate of the waste-generated gases, but it is only diminished via ventilation, whereas the waste gases are continuously released by the waste and may be subject to depletion mechanisms other than ventilation. The fiscal year 1998 tracer studies provide new evidence that significant exchange of air occurs between tanks via the underground cascade pipes. Most of the single-shell waste tanks are connected via 7.6-cm diameter cascade pipes to one or two adjacent tanks. Tracer gas studies of the Tank U-102/U-103 system indicated that the ventilation occurring via the cascade line could be a significant fraction of the total ventilation. In this two-tank cascade, air evidently flowed from Tank U-103 to Tank U-102 for a time and then was observed to flow from Tank U-102 to Tank U-103

Using a New Modification on Wind Turbine Ventilator for Improving Indoor Air Quality

Directory of Open Access Journals (Sweden)

Louay Abdul salam Rasheed

2018-02-01

Full Text Available This paper describes a newly modified wind turbine ventilator that can achieve highly efficient ventilation. The new modification on the conventional wind turbine ventilator system may be achieved by adding a Savonius wind turbine above the conventional turbine to make it work more efficiently and help spinning faster. Three models of the Savonius wind turbine with 2, 3, and 4 blades' semicircular arcs are proposed to be placed above the conventional turbine of wind ventilator to build a hybrid ventilation turbine. A prototype of room model has been constructed and the hybrid turbine is placed on the head of the room roof. Performance's tests for the hybrid turbine with a different number of blades and different values of wind speeds have been conducted. The experimental test results show that the performance of the improved ventilation turbine with three blades is the best. It is found that the maximum rotation speed of the improved turbine is 107rpm, while the air flow rate is 0.0103m3/s and the air change rate per hour is 32.67hr-1, at a wind speed of 3m/s. The proposed design has been achieved an increase in the turbine rotational speed, increase of the extraction rate of the indoor air and the air-changes per hour, provided the requisite ventilation and improved the quality of the indoor air.

The effect of ventilation on the indoor air concentration of PCB

DEFF Research Database (Denmark)

Lyng, Nadja; Gunnarsen, Lars Bo; Andersen, Helle Vibeke

2015-01-01

The impact of increased ventilation on polychlorinated biphenyl (PCB) air concentration by installation of mechanical balanced ventilation units was studied. The intervention was carried out in three PCB-contaminated rooms; one classroom in an elementary school and two small bedrooms...... in an apartment in a residential building. In the classroom, the air exchange rate (ACH) was raised from 0.2 (without mechanical ventilation) to 5.5 /h during the intervention. In the two bedrooms, the highest ACH was 6.6 /h and 0.5 /h without mechanical ventilation. The corresponding concentration decrease...

Characteristics of coal mine ventilation air flows.

Science.gov (United States)

Su, Shi; Chen, Hongwei; Teakle, Philip; Xue, Sheng

2008-01-01

Coal mine methane (CMM) is not only a greenhouse gas but also a wasted energy resource if not utilised. Underground coal mining is by far the most important source of fugitive methane emissions, and approximately 70% of all coal mining related methane is emitted to the atmosphere through mine ventilation air. Therefore, research and development on mine methane mitigation and utilisation now focuses on methane emitted from underground coal mines, in particular ventilation air methane (VAM) capture and utilisation. To date, most work has focused on the oxidation of very low concentration methane. These processes may be classified based on their combustion kinetic mechanisms into thermal oxidation and catalytic oxidation. VAM mitigation/utilisation technologies are generally divided into two basic categories: ancillary uses and principal uses. However, it is possible that the characteristics of ventilation air flows, for example the variations in methane concentration and the presence of certain compounds, which have not been reported so far, could make some potential VAM mitigation and utilisation technologies unfeasible if they cannot cope with the characteristics of mine site ventilation air flows. Therefore, it is important to understand the characteristics of mine ventilation air flows. Moreover, dust, hydrogen sulphide, sulphur dioxide, and other possible compounds emitted through mine ventilation air into the atmosphere are also pollutants. Therefore, this paper presents mine-site experimental results on the characteristics of mine ventilation air flows, including methane concentration and its variations, dust loadings, particle size, mineral matter of the dust, and other compounds in the ventilation air flows. The paper also discusses possible correlations between ventilation air characteristics and underground mining activities.

Ventilation, indoor air quality, and human health and comfort in dwellings and day-care centers

Energy Technology Data Exchange (ETDEWEB)

Ruotsalainen, R.

1995-12-31

The objective of the study was to assess the actual ventilation and indoor air quality in the Finnish building stock (dwellings and day-care centers) with special reference to the existing guideline values. Furthermore, the objective was to evaluate the occurrence of symptoms and perceptions among occupants (adult residents, children, workers) in relation to ventilation system, ventilation rate and dampness. The measurements of ventilation and indoor air quality in the dwellings and day-care centers included ventilation rate, CO{sub 2} concentration, and temperature and humidity. Self- and parent-administered questionnaires were distributed to the occupants inquiring their personal characteristics, occurrence of symptoms of interest, perceived indoor air quality and details of their home and work environments. Airflows and air change rates varied remarkably both in the dwellings and day-care centers. In the majority of the dwellings and day-care centers, the Finnish guideline values of ventilation rates were not achieved. No consistent associations were observed between the magnitude of mechanical ventilation rates and the occurrence of eye, respiratory, skin and general symptoms, that is, symptoms of sick building syndrome (SBS) among the day-care workers. The results indicate that there is much room for improvement in the ventilation and indoor air quality of Finnish dwellings and day-care centers. The control of ventilation, temperature and humidity and the prevention of water damage are important issues on which to concentrate in the future. There is need to improve the quality in all phases of construction: design, installation, adjustment, operation, and maintenance

Ventilation, indoor air quality, and human health and comfort in dwellings and day-care centers

Energy Technology Data Exchange (ETDEWEB)

Ruotsalainen, R

1996-12-31

The objective of the study was to assess the actual ventilation and indoor air quality in the Finnish building stock (dwellings and day-care centers) with special reference to the existing guideline values. Furthermore, the objective was to evaluate the occurrence of symptoms and perceptions among occupants (adult residents, children, workers) in relation to ventilation system, ventilation rate and dampness. The measurements of ventilation and indoor air quality in the dwellings and day-care centers included ventilation rate, CO{sub 2} concentration, and temperature and humidity. Self- and parent-administered questionnaires were distributed to the occupants inquiring their personal characteristics, occurrence of symptoms of interest, perceived indoor air quality and details of their home and work environments. Airflows and air change rates varied remarkably both in the dwellings and day-care centers. In the majority of the dwellings and day-care centers, the Finnish guideline values of ventilation rates were not achieved. No consistent associations were observed between the magnitude of mechanical ventilation rates and the occurrence of eye, respiratory, skin and general symptoms, that is, symptoms of sick building syndrome (SBS) among the day-care workers. The results indicate that there is much room for improvement in the ventilation and indoor air quality of Finnish dwellings and day-care centers. The control of ventilation, temperature and humidity and the prevention of water damage are important issues on which to concentrate in the future. There is need to improve the quality in all phases of construction: design, installation, adjustment, operation, and maintenance

Evaluation of the indoor air quality minimum ventilation rate procedure for use in California retail buildings.

Science.gov (United States)

Dutton, S M; Mendell, M J; Chan, W R; Barrios, M; Sidheswaran, M A; Sullivan, D P; Eliseeva, E A; Fisk, W J

2015-02-01

This research assesses benefits of adding to California Title-24 ventilation rate (VR) standards a performance-based option, similar to the American Society of Heating, Refrigerating, and Air Conditioning Engineers 'Indoor Air Quality Procedure' (IAQP) for retail spaces. Ventilation rates and concentrations of contaminants of concern (CoC) were measured in 13 stores. Mass balance models were used to estimate 'IAQP-based' VRs that would maintain concentrations of all CoCs below health- or odor-based reference concentration limits. An intervention study in a 'big box' store assessed how the current VR, the Title 24-prescribed VR, and the IAQP-based VR (0.24, 0.69, and 1.51 air changes per hour) influenced measured IAQ and perceived of IAQ. Neither current VRs nor Title 24-prescribed VRs would maintain all CoCs below reference limits in 12 of 13 stores. In the big box store, the IAQP-based VR kept all CoCs below limits. More than 80% of subjects reported acceptable air quality at all three VRs. In 11 of 13 buildings, saving energy through lower VRs while maintaining acceptable IAQ would require source reduction or gas-phase air cleaning for CoCs. In only one of the 13 retail stores surveyed, application of the IAQP would have allowed reduced VRs without additional contaminant-reduction strategies. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Effect of ventilation rate on concentrations of indoor radon and its progenies

International Nuclear Information System (INIS)

Wang Chunhong; Liu Yanyang; Liu Fudong; Liu Senlin; Chen Ling

2012-01-01

To study concentrations of indoor radon and its progenies, ventilation rates and their corresponding concentrations of indoor radon and its progenies were measured using tracer-gas dilution method. Results show that both ventilation rates and concentrations of indoor radon varied insignificantly and radon concentration were higher than the outdoor environment while doors and windows were all closed with air-conditioner on and off respectively; the concentrations declined and close to the outdoor level when doors and windows were all open with ventilators in operation. Accordingly, in modern life, especially in summer, people's preference for air-conditioners but natural ventilation would result in an increase of indoor radon concentration. (authors)

Assessment of ventilation and indoor air pollutants in nursery and elementary schools in France.

Science.gov (United States)

Canha, N; Mandin, C; Ramalho, O; Wyart, G; Ribéron, J; Dassonville, C; Hänninen, O; Almeida, S M; Derbez, M

2016-06-01

The aim of this study was to characterize the relationship between Indoor Air Quality (IAQ) and ventilation in French classrooms. Various parameters were measured over one school week, including volatile organic compounds, aldehydes, particulate matter (PM2.5 mass concentration and number concentration), carbon dioxide (CO2 ), air temperature, and relative humidity in 51 classrooms at 17 schools. The ventilation was characterized by several indicators, such as the air exchange rate, ventilation rate (VR), and air stuffiness index (ICONE), that are linked to indoor CO2 concentration. The influences of the season (heating or non-heating), type of school (nursery or elementary), and ventilation on the IAQ were studied. Based on the minimum value of 4.2 l/s per person required by the French legislation for mechanically ventilated classrooms, 91% of the classrooms had insufficient ventilation. The VR was significantly higher in mechanically ventilated classrooms compared with naturally ventilated rooms. The correlations between IAQ and ventilation vary according to the location of the primary source of each pollutant (outdoor vs. indoor), and for an indoor source, whether it is associated with occupant activity or continuous emission. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Radon mitigation in schools utilising heating, ventilating and air conditioning systems

International Nuclear Information System (INIS)

Fisher, G.; Ligman, B.; Brennan, T.; Shaughnessy, R.; Turk, B.H.; Snead, B.

1994-01-01

As part of a continuing radon in schools technology development effort, EPA's School Evaluation Team has performed radon mitigation in schools by the method of ventilation/pressurisation control technology. Ventilation rates were increased, at a minimum, to meet the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) standard, Ventilation for Acceptable Indoor Air Quality (ASHRAE 62-1989). This paper presents the results and the preliminary evaluations which led to the team's decision to implement this technology. Factors considered include energy penalties, comfort, indoor air quality (IAQ), building shell tightness, and equipment costs. Cost benefit of heat recovery ventilation was also considered. Earlier results of the SEP team's efforts have indicated a severe ventilation problem within the schools of the United States. Two case studies are presented where HVAC technology was implemented for controlling radon concentrations. One involved the installation of a heat recovery ventilator to depressurise a crawl space and provide ventilation to the classrooms which previously had no mechanical ventilation. The other involved the restoration of a variable air volume system in a two-storey building. The HVAC system's controls were restored and modified to provide a constant building pressure differential to control the entry of radon. Pre-mitigation and post-mitigation indoor air pollutant measurements were taken, including radon, carbon dioxide (CO 2 ), particulates, and bio-aerosols. Long-term monitoring of radon, CO 2 , building pressure differentials, and indoor/outdoor temperature and relative humidity is presented. (author)

Measurements and prediction of inhaled air quality with personalized ventilation

DEFF Research Database (Denmark)

Cermak, Radim; Majer, M.; Melikov, Arsen Krikor

2002-01-01

the room air) at flow rates ranging from less than 5 L/s up to 23 L/s. The air quality assessment was based on temperature measurements of the inhaled air and on the portion of the personalized air inhaled. The percentage of dissatisfied with the air quality was predicted. The results suggest......This paper examines the performance of five different air terminal devices for personalized ventilation in relation to the quality of air inhaled by a breathing thermal manikin in a climate chamber. The personalized air was supplied either isothermally or non-isothermally (6 deg.C cooler than...... that regardless of the temperature combinations, personalized ventilation may decrease significantly the number of occupants dissatisfied with the air quality. Under non-isothermal conditions the percentage of dissatisfied may decrease up to 4 times....

New Air Cleaning Strategies for Reduced Commercial Building Ventilation Energy ? FY11 Final Report

Energy Technology Data Exchange (ETDEWEB)

Sidheswaran, Meera; Destaillats, Hugo; Cohn, Sebastian; Sullivan, Douglas P.; Fisk, William J.

2011-10-31

The research carried out in this project focuses on developing novel volatile organic compounds (VOCs) air cleaning technologies needed to enable energy-saving reductions in ventilation rates. we targeted a VOC air cleaning system that could enable a 50% reduction in ventilation rates. In a typical commercial HVAC system that provides a mixture of recirculated and outdoor air, a VOC air cleaner in the supply airstream must have a 15% to 20% VOC removal efficiency to counteract a 50% reduction in outdoor air supply.

Ductless personalized ventilation with local air cleaning

DEFF Research Database (Denmark)

Dalewski, Mariusz; Vesely, Michal; Melikov, Arsen Krikor

2012-01-01

An experiment with 28 human subjects was performed to examine effects of using a local air cleaning device combined with ductless personalized ventilation (DPV) on perceived air quality. Experiments were performed in a test room with displacement ventilation. The DPV at one of two desks was equip......An experiment with 28 human subjects was performed to examine effects of using a local air cleaning device combined with ductless personalized ventilation (DPV) on perceived air quality. Experiments were performed in a test room with displacement ventilation. The DPV at one of two desks...... was equipped with an activated carbon filter installed at the air intake, while the DPV at the second desk was without such a filter. The air temperature in the occupied zone (1.1 m above the floor) was 29 °C. The pollution load in the room was simulated by PVC floor covering. The subjects assessed...

21 CFR 211.46 - Ventilation, air filtration, air heating and cooling.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Ventilation, air filtration, air heating and cooling. 211.46 Section 211.46 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Buildings and Facilities § 211.46 Ventilation, air filtration, air heating and cooling. (a) Adequate...

Indoor air quality in mechanically ventilated residential dwellings/low-rise buildings: A review of existing information

DEFF Research Database (Denmark)

Aganovic, Amar; Hamon, Mathieu; Kolarik, Jakub

Mechanical ventilation has become a mandatory requirement in multiple European standards addressing indoor air quality (IAQ) and ventilation in residential dwellings (single family houses and low-rise apartment buildings). This article presents the state of the art study through a review...... of the existing literature, to establish a link between ventilation rate and key indoor air pollutants. Design characteristics of a mechanical ventilation system such as supply/exhaustairflow, system and design of supply and exhaust outlets were considered. The performance of various ventilation solutionswas......-house ventilation rate was reported below 0.5h-1 or 14 l/s·person in bedrooms, the concentrations of the pollutants elevated above minimum threshold limits (CO2>1350 ppm; TVOC >3000 μg/m3) defined by the standard. Insufficient or non-existent supply of air was related to significantly higher pollutant...

Temperature ranges of the application of air-to-air heat recovery ventilator in supermarkets in winter, China

Energy Technology Data Exchange (ETDEWEB)

Kang, Yanming; Wang, Youjun; Zhong, Ke [School of Environmental Science and Engineering, Donghua University, Shanghai 201620 (China); Liu, Jiaping [School of Architecture, Xi' an University of Architecture and Technology, Xi' an 710055 (China)

2010-12-15

Energy consumption is an important issue in China. In heating, ventilation and air conditioning (HVAC) systems, more and more commercial buildings use air-to-air heat recovery ventilators as energy saving units for recovering heat from the exhaust air in ventilation systems in current years. In the present paper, critical temperatures of air-to-air heat recovery systems for supermarkets in winter are recommended and discussed for the four cities in different climate zones of China. The analysis shows that the temperature of fresh air in winter can be categorized into three regions, i.e., recovery region, transition region and impermissible recovery region. The results also indicate that the latent heat recovery is not suitable for ventilation energy savings in supermarkets in winter. Meanwhile, the applicability of sensible heat recovery in supermarkets depends on outdoor climate and fresh air flow rate. If a variable rotational speed fan is used to introduce fresh air into the building, heat recovery does always function as planned in winter for all the selected cities except Guangzhou, and most values of the COP are much higher than 2.5. Otherwise, there is the risk of negative impact on building energy savings in all cities except Harbin. (author)

Air Distribution Effectiveness for Residential Mechanical Ventilation: Simulation and Comparison of Normalized Exposures

Energy Technology Data Exchange (ETDEWEB)

Petithuguenin, T.D.P.; Sherman, M.H.

2009-05-01

The purpose of ventilation is to dilute indoor contaminants that an occupant is exposed to. Even when providing the same nominal rate of outdoor air, different ventilation systems may distribute air in different ways, affecting occupants' exposure to household contaminants. Exposure ultimately depends on the home being considered, on source disposition and strength, on occupants' behavior, on the ventilation strategy, and on operation of forced air heating and cooling systems. In any multi-zone environment dilution rates and source strengths may be different in every zone and change in time, resulting in exposure being tied to occupancy patterns.This paper will report on simulations that compare ventilation systems by assessing their impact on exposure by examining common house geometries, contaminant generation profiles, and occupancy scenarios. These simulations take into account the unsteady, occupancy-tied aspect of ventilation such as bathroom and kitchen exhaust fans. As most US homes have central HVAC systems, the simulation results will be used to make appropriate recommendations and adjustments for distribution and mixing to residential ventilation standards such as ASHRAE Standard 62.2.This paper will report on work being done to model multizone airflow systems that are unsteady and elaborate the concept of distribution matrix. It will examine several metrics for evaluating the effect of air distribution on exposure to pollutants, based on previous work by Sherman et al. (2006).

Indoor air pollutants, ventilation rate determinants and potential control strategies in Chinese dwellings: A literature review.

Science.gov (United States)

Ye, Wei; Zhang, Xu; Gao, Jun; Cao, Guangyu; Zhou, Xiang; Su, Xing

2017-05-15

After nearly twenty years of rapid modernization and urbanization in China, huge achievements have transformed the daily lives of the Chinese people. However, unprecedented environmental consequences in both indoor and outdoor environments have accompanied this progress and have triggered public awareness and demands for improved living standards, especially in residential environments. Indoor pollution data measured for >7000 dwellings (approximately 1/3 were newly decorated and were tested for volatile organic compound (VOC) measurements, while the rest were tested for particles, phthalates and other semi-volatile organic compounds (SVOCs), moisture/mold, inorganic gases and radon) in China within the last ten years were reviewed, summarized and compared with indoor concentration recommendations based on sensory or health end-points. Ubiquitous pollutants that exceed the concentration recommendations, including particulate matter, formaldehyde, benzene and other VOCs, moisture/mold, inorganic gases and radon, were found, indicating a common indoor air quality (IAQ) issue in Chinese dwellings. With very little prevention, oral, inhalation and dermal exposure to those pollutants at unhealthy concentration levels is almost inevitable. CO 2 , VOCs, humidity and radon can serve as ventilation determinants, each with different ventilation demands and strategies, at typical occupant densities in China; and particle reduction should be a prerequisite for determining ventilation requirements. Two directional ventilation modes would have profound impacts on improving IAQ for Chinese residences are: 1) natural (or window) ventilation with an air cleaner and 2) mechanical ventilation with an air filtration unit, these two modes were reviewed and compared for their applicability and advantages and disadvantages for reducing human exposure to indoor air pollutants. In general, mode 2 can more reliably ensure good IAQ for occupants; while mode 1 is more applicable due to its

Ventilation influence upon indoor air radon level

International Nuclear Information System (INIS)

Tian Deyuan

1995-01-01

Levels of indoor radon in air are studied by a continuous electrostatic radon monitor under normal living conditions to evaluate the influence of air conditioned ventilation on indoor air radon level. Results show that the indoor air radon concentrations are not much more than those without household conditioner living condition, although using household conditioner requires a sealed room which should lead to a higher radon level. Turning on air conditioner helps lower indoor radon level. Therefore, the total indoor air Rn levels are normal > ventilation > exhaust or in-draft > exhaust plus in-draft

Ventilation-air conditioning system

International Nuclear Information System (INIS)

Kubokoya, Takashi.

1991-01-01

Heretofore, in ventilation-air conditioning systems in a nuclear power plant, exhaust gases from each of the ventilation-air conditioning systems of a reactor building, a turbine building, a waste processing building are joined and they are released into atmosphere from the top of a high main exhaustion stack. In order to build such a high main exhaustion stack, a considerable construction cost is required and, in addition, there is a worry of lacking balance with surrounding scenery. Then, in the present invention, exhaust gases are heated by waste heat in a turbine during their introduction from the ventilation-air conditioning facility in the building of a power plant to the main exhaust stack. With such a constitution, since the exhaust gases are heated and their temperature is elevated, they uprise by natural convection when they are released from the top of the main exhaustion stack to the atmosphere. Accordingly, they are released to a level higher than the conventional case in view of the volume of the blower which sends the exhaust gases under pressure, to diffuse them to the atmosphere more sufficiently compared with a conventional case. Further, the height of the main exhaustion stack can be reduced, enabling to minimize the cost for moving the blower. (T.M.)

Air Distribution in a Furnished Room Ventilated by Mixing Ventilation

DEFF Research Database (Denmark)

Nielsen, June Richter; Nielsen, Peter V.; Svidt, Kjeld

Using isothermal full-scale experiments and two-dimensional isothermal CFD simulations it is investigated how normal office furniture influences the air movements in a room with mixing ventilation. Three different set-ups are made in the experiments and different sizes and locations of the furnit......Using isothermal full-scale experiments and two-dimensional isothermal CFD simulations it is investigated how normal office furniture influences the air movements in a room with mixing ventilation. Three different set-ups are made in the experiments and different sizes and locations...

Thermal Plumes in Ventilated Rooms

DEFF Research Database (Denmark)

Kofoed, P.; Nielsen, Peter Vilhelm

The main objective of ventilation is to provide good air quality for the occupants. For this purpose the necessary ventilating air change rate must be determined. Within displacement ventilation the estimation is closely related to the air flow rate in the thermal plumes when an air quality based...

Seat headrest-incorporated personalized ventilation: Thermal comfort and inhaled air quality

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Ivanova, T.; Stefanova, G.

2012-01-01

inhaled by the manikin was measured and used to assess the clean air supply efficiency of the SHPV. The response of 35 subjects was collected to examine thermal comfort with the SHPV. The subjects participated in 3 experiments at personalized air temperature and room air temperature of 22/20 °C, 23/23 °C......The performance of personalized ventilation with seat headrest-mounted air supply terminal devices (ATD), named seat headrest personalized ventilation (SHPV), was studied. Physical measurements using a breathing thermal manikin were taken to identify its ability to provide clean air to inhalation...... depending on design, shape, size and positioning of the ATD, flow rate and temperature of personalized air, room temperature, clothing thermal insulation of the manikin, etc. Tracer gas was mixed with the room air. The air supplied by the SHPV was free of tracer gas. Tracer gas concentration in the air...

Indoor Air Quality and Ventilation in Residential Deep Energy Retrofits

Energy Technology Data Exchange (ETDEWEB)

Less, Brennan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Walker, Iain [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2014-06-01

Because airtightening is a significant part of Deep Energy Retrofits (DERs), concerns about ventilation and Indoor Air Quality (IAQ) have emerged. To investigate this, ventilation and IAQ were assessed in 17 non-smoking California Deep Energy Retrofit homes. Inspections and surveys were used to assess household activities and ventilation systems. Pollutant sampling performed in 12 homes included six-day passive samples of nitrogen dioxide (NO₂), formaldehyde and air exchange rate (AER); time-resolved data loggers were used to measure particle counts. Half of the homes provided continuous mechanical ventilation. Despite these homes being twice as airtight (3.0 and 7.6 ACH50, respectively), their median AER was indistinguishable from naturally vented homes (0.36 versus 0.37 hr^-1). Numerous problems were found with ventilation systems; however, pollutant levels did not reach levels of concern in most homes. Ambient NO₂ standards were exceeded in some gas cooking homes that used legacy ranges with standing pilots, and in Passive House-style homes without range hoods exhausted to outside. Cooking exhaust systems were installed and used inconsistently. The majority of homes reported using low-emitting materials, and formaldehyde levels were approximately half those in conventional new CA homes (19.7 versus 36 μg/m³), with emissions rates nearly 40percent less (12.3 versus 20.6 μg/m²/hr.). Presence of air filtration systems led to lower indoor particle number concentrations (PN_>0.5: 8.80E+06 PN/m³ versus 2.99E+06; PN_>2.5: 5.46E+0.5 PN/m³ versus 2.59E+05). The results indicate that DERs can provide adequate ventilation and IAQ, and that DERs should prioritize source control, particle filtration and well-designed local exhaust systems, while still providing adequate continuous ventilation.

Can we establish relationship between outdoor air ventilation and health based on the published epidemiological data?

DEFF Research Database (Denmark)

Carrer, Paolo; Wargocki, Pawel; Fanetti, Annaclara

2015-01-01

Appropriate exposure control is prerogative for reducing the burden of disease (BOD) due to inadequate air quality indoors (IAQ). Ventilation with outdoor air is one of the available exposure control methods and is widespread. It is often assumed that this method will bring tangible effects...... exposures at various levels of ventilation were no characterized. It was observed that available data have many limitations, such as insufficient statistical power, incomplete data on the strength of pollution sources, diversity and variability of ventilation rates, at which effects have been seen...... exposures affecting health. It is concluded, that currently available epidemiological data do not provide sound basis for outdoor air ventilation requirements that can be universally applicable in different public and residential buildings to protect against health risks. They show minimum rates at which...

Air change. Ventilation requirements of closed rooms

Energy Technology Data Exchange (ETDEWEB)

Cords, W

1988-04-01

Closed rooms have to be ventilated in order to compensate influences changing the composition and quality of air. Details are given on the conditions and factors determining the required change of air as well as the design of ventilation systems. Reference is made to the respiratory consumption of oxygen, the increase of hazardous carbon dioxide contents causing headaches and indispositions, water vapor exhalations, body heat, odors, cold air coming in from outside, bodily heat losses, carbon dioxide limiting values, air speeds, and air pressures inside rooms. The humidity and temperatures of frequented rooms should keep within the maximum values. (HWJ).

Balancing energy conservation and occupant needs in ventilation rate standards for Big Box stores and other commercial buildings in California. Issues related to the ASHRAE 62.1 Indoor Air Quality Procedure

Energy Technology Data Exchange (ETDEWEB)

Mendell, Mark J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Apte, Mike G. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2010-10-31

This report considers the question of whether the California Energy Commission should incorporate the ASHRAE 62.1 ventilation standard into the Title 24 ventilation rate (VR) standards, thus allowing buildings to follow the Indoor Air Quality Procedure. This, in contrast to the current prescriptive standard, allows the option of using ventilation rate as one of several strategies, which might include source reduction and air cleaning, to meet specified targets of indoor air concentrations and occupant acceptability. The research findings reviewed in this report suggest that a revised approach to a ventilation standard for commercial buildings is necessary, because the current prescriptive ASHRAE 62.1 Ventilation Rate Procedure (VRP) apparently does not provide occupants with either sufficiently acceptable or sufficiently healthprotective air quality. One possible solution would be a dramatic increase in the minimum ventilation rates (VRs) prescribed by a VRP. This solution, however, is not feasible for at least three reasons: the current need to reduce energy use rather than increase it further, the problem of polluted outdoor air in many cities, and the apparent limited ability of increasing VRs to reduce all indoor airborne contaminants of concern (per Hodgson (2003)). Any feasible solution is thus likely to include methods of pollutant reduction other than increased outdoor air ventilation; e.g., source reduction or air cleaning. The alternative 62.1 Indoor Air Quality Procedure (IAQP) offers multiple possible benefits in this direction over the VRP, but seems too limited by insufficient specifications and inadequate available data to provide adequate protection for occupants. Ventilation system designers rarely choose to use it, finding it too arbitrary and requiring use of much non-engineering judgment and information that is not readily available. This report suggests strategies to revise the current ASHRAE IAQP to reduce its current limitations. These

A novel complex air supply model for indoor air quality control via the occupant micro-environment demand ventilation

International Nuclear Information System (INIS)

Yang, Jie; Zhou, Bo; Jin, Maozhu; Wang, Jun; Xiong, Feng

2016-01-01

Protection of indoor air quality and human health can be achieved via ventilation, which has becomes one of the most important tasks for sustainable buildings. This approach also requires highly efficient and energy saving methods for modern building ventilations consisting of a set of parameters of the complex indoor system. Therefore, the advancement in understanding the characteristics of various ventilation methods is highly necessary. This study presents one novel air supply model for the complex occupant micro-environment demand control ventilations, to analyze the efficiency of various ventilation types. This model is established primarily according to the momentum and mass conservations, and goal of occupant micro-environment demand, which is a complex system with the characteristics of diversity and dynamic variation. As for different occupant densities, characteristics of outdoor air supply for controlling gaseous pollutant and three basic features of outdoor airflow supply reaching occupant micro-environment were obtained. This research shows that for various types of occupant density and storey height, the rising and descending rates of the demand outdoor airflow in mixing ventilation are higher than those under displacement ventilation conditions. In addition, since the structure is better designed and sewage flow is more efficient, the mixing ventilation also requires a much higher peak demand outdoor airflow than its counterpart. The increase of storey height will lead to a decline of pollutants in the breathing zone and the demand outdoor airflow. Fluctuations of air flow diffusion caused by the change of occupant density in architectural space, will lead to variations of outdoor airflow reaching occupant micro-environment. Accordingly, it would lead to the different peak values of demand outdoor airflow, and the difference becomes even significant if the occupant density increases. The variations of the air supply and fraction of air reaching the

Ventilation system design for educational facilities

Energy Technology Data Exchange (ETDEWEB)

Elsafty, A.F.; Abo Elazm, M.M. [Arab Academy for Science, Alexandria (Egypt). Technology and Maritime Transport; Safwan, M. [Arab Academy for Science, Cairo (Egypt). Technology and Maritime Transport

2010-07-01

In order to maintain acceptable indoor air quality levels in classrooms, high ventilation rates are needed to dilute the concentration of indoor contaminants, resulting in higher energy consumption for the operation of mechanical ventilation systems. Three factors are usually considered when determining the adequate ventilation rate for classrooms in educational facilities. These include the maximum population served in the classroom; carbon dioxide (CO{sub 2}) production rate by occupants; and outdoor air conditions. CO{sub 2} concentrations usually indicate the rate of ventilation required. This paper presented a newly developed computer software program for determining the ventilation rates needed to enhance indoor air quality and to maintain CO{sub 2} concentration within the recommended levels by ANSI/ASHRAE standards for best student performance. This paper also presented design curves for determining the ventilation rates and air changes per hour required for the ventilated educational zone. 15 refs., 2 tabs., 5 figs.

Seat-integrated localized ventilation for exposure reduction to air pollutants in indoor environments

DEFF Research Database (Denmark)

Bivolarova, Mariya Petrova; Rezgals, Lauris; Melikov, Arsen Krikor

2016-01-01

A novel ventilation method for minimizing the spread of bioeffluent contaminants generated from sedentary people indoors was developed and studied. The concept of the method consists of a ventilated cushion which is able to suck the human bioeffluents at the area of the body where they are mainly...... generated before they disperse around a room. The polluted near the body air is exhausted into the cushion and it is removed from the room by a separate exhaust system. The performance of the method was studied in series of experiments. Full-scale room and a dressed thermal manikin sitting in front....... The experiments were conducted at 26°C room air temperature. The performance of the VC in conjunction with mixing total-volume background ventilation at 1 air change per hour (ACH) was compared with that of mixing background ventilation alone operating at 1, 1.5, 3 and 6 ACH. Experiments at exhaust airflow rate...

Short-term airing by natural ventilation - modeling and control strategies.

Science.gov (United States)

Perino, M; Heiselberg, P

2009-10-01

The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. This kind of system frequently integrates traditional mechanical ventilation components with natural ventilation devices, such as motorized windows and louvers. Among the various ventilation strategies that are currently available, buoyancy driven single-sided natural ventilation has proved to be very effective and can provide high air change rates for temperature and IAQ control. However, in order to promote a wider applications of these systems, an improvement in the knowledge of their working principles and the availability of new design and simulation tools is necessary. In this context, the paper analyses and presents the results of a research that was aimed at developing and validating numerical models for the analysis of buoyancy driven single-sided natural ventilation systems. Once validated, these models can be used to optimize control strategies in order to achieve satisfactory indoor comfort conditions and IAQ. Practical Implications Numerical and experimental analyses have proved that short-term airing by intermittent ventilation is an effective measure to satisfactorily control IAQ. Different control strategies have been investigated to optimize the capabilities of the systems. The proposed zonal model has provided good performances and could be adopted as a design tool, while CFD simulations can be profitably used for detailed studies of the pollutant concentration distribution in a room and to address local discomfort problems.

[Air quality control systems: heating, ventilating, and air conditioning (HVAC)].

Science.gov (United States)

Bellucci Sessa, R; Riccio, G

2004-01-01

After a brief illustration of the principal layout schemes of Heating, Ventilating, and Air Conditioning (HVAC), the first part of this paper summarizes the standards, both voluntary and compulsory, regulating HVAC facilities design and installation with regard to the question of Indoor Air Quality (IAQ). The paper then examines the problem of ventilation systems maintenance and the essential hygienistic requirements in whose absence HVAC facilities may become a risk factor for people working or living in the building. Lastly, the paper deals with HVAC design strategies and methods, which aim not only to satisfy comfort and air quality requirements, but also to ensure easy and effective maintenance procedures.

Ventilation Effectiveness

DEFF Research Database (Denmark)

Mundt, M.; Mathisen, H. M.; Moser, M.

Improving the ventilation effectiveness allows the indoor air quality to be significantly enhanced without the need for higher air changes in the building, thereby avoiding the higher costs and energy consumption associated with increasing the ventilation rates. This Guidebook provides easy-to-un...

Computer program for sizing residential energy recovery ventilator

International Nuclear Information System (INIS)

Koontz, M.D.; Lee, S.M.; Spears, J.W.; Kesselring, J.P.

1991-01-01

Energy recovery ventilators offer the prospect of tighter control over residential ventilation rates than manual methods, such as opening windows, with a lesser energy penalty. However, the appropriate size of such a ventilator is not readily apparent in most situations. Sizing of energy recovery ventilation software was developed to calculate the size of ventilator necessary to satisfy ASHRAE Standard 62-1989, Ventilation for Acceptable Air Quality, or a user-specified air exchange rate. Inputs to the software include house location, structural characteristics, house operations and energy costs, ventilation characteristics, and HVAC system COP/efficiency. Based on these inputs, the program estimates the existing air exchange rate for the house, the ventilation rate required to meet the ASHRAE standard or user-specified air exchange rate, the size of the ventilator needed to meet the requirement, and the expected changes in indoor air quality and energy consumption. In this paper an illustrative application of the software is provided

Uranium mine ventilation

International Nuclear Information System (INIS)

Katam, K.; Sudarsono

1982-01-01

Uranium mine ventilation system aimed basically to control and decreasing the air radioactivity in mine caused by the radon emanating from uranium ore. The control and decreasing the air ''age'' in mine, with adding the air consumption volume, increasing the air rate consumption, closing the mine-out area; using closed drainage system. Air consumption should be 60m 3 /minute for each 9m 2 uranium ore surfaces with ventilation rate of 15m/minute. (author)

Heat Recovery Ventilation for Housing: Air-to-Air Heat Exchangers.

Science.gov (United States)

Corbett, Robert J.; Miller, Barbara

The air-to-air heat exchanger (a fan powered ventilation device that recovers heat from stale outgoing air) is explained in this six-part publication. Topic areas addressed are: (1) the nature of air-to-air heat exchangers and how they work; (2) choosing and sizing the system; (3) installation, control, and maintenance of the system; (4) heat…

Estimation of uncertainty in tracer gas measurement of air change rates.

Science.gov (United States)

Iizuka, Atsushi; Okuizumi, Yumiko; Yanagisawa, Yukio

2010-12-01

Simple and economical measurement of air change rates can be achieved with a passive-type tracer gas doser and sampler. However, this is made more complex by the fact many buildings are not a single fully mixed zone. This means many measurements are required to obtain information on ventilation conditions. In this study, we evaluated the uncertainty of tracer gas measurement of air change rate in n completely mixed zones. A single measurement with one tracer gas could be used to simply estimate the air change rate when n = 2. Accurate air change rates could not be obtained for n ≥ 2 due to a lack of information. However, the proposed method can be used to estimate an air change rate with an accuracy of air change rate can be avoided. The proposed estimation method will be useful in practical ventilation measurements.

Impact of airflow interaction on inhaled air quality and transport of contaminants in rooms with personalized and total volume ventilation

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Cermak, Radim; Kovar, O.

2003-01-01

The impact of airflow interaction on inhaled air quality and transport of contaminants between occupants was studied in regard to pollution from floor covering, human bioeffluents and exhaled air, with combinations of two personalized ventilation systems (PV) with mixing and displacement...... quality with personalized and mixing ventilation was higher or at least similar compared to mixing ventilation alone. In the case of PV combined with displacement ventilation, the interaction caused mixing of the room air, an increase in the transport of bioeffluents and exhaled air between occupants and...... ventilation. In total, 80 L/s of clean air supplied at 20°C was distributed between the ventilation systems at different combinations of personalized airflow rate. Two breathing thermal manikins were used to simulate occupants in a full-scale test room. Regardless of the airflow interaction, the inhaled air...

Ventilation effectiveness

CERN Document Server

Mathisen, Hans Martin; Nielsen, Peter V; Moser, Alfred

2004-01-01

Improving the ventilation effectiveness allows the indoor air quality to be significantly enhanced without the need for higher air changes in the building, thereby avoiding the higher costs and energy consumption associated with increasing the ventilation rates. This Guidebook provides easy-to-understand descriptions of the indices used to mesure the performance of a ventilation system and which indices to use in different cases.

Effect of ventilation on perceived quality of air polluted by building materials. A summary of reported data

Energy Technology Data Exchange (ETDEWEB)

Wargocki, P.; Vondruskova, J. (International Centre for Indoor Environment and Energy, Dept. of Mechanical Engineering, DTU, Kgs. Lyngby (DK)); Knudsen, Henrik N. (Danish Building Research Institute, Aalborg Univ., Hoersholm (DK))

2007-02-15

This paper summarizes existing data on how varying ventilation rates affect the perceived quality of air polluted by building materials. This is done by reviewing literature dealing with exposure-response relationships, i.e. the log-linear relationships between the concentration of pollutants (exposure) and the perceived air quality (response). The reviewed data originate from studies with single building materials performed in small-scale ventilated chambers and from studies carried out in a full-scale setting resembling normal offices. Perceived air quality expressed in terms of acceptability as assessed by untrained panels was included. The results show that the exposure-response relationships vary for different building materials as regards the impact of changing ventilation rate on perceived air quality and the level of perceived air quality at a constant ventilation rate. This applies both for the data collected in small-scale and in full-scale experiments. The differences may be caused by the experimental conditions, psychological factors, physiological factors, and chemical/physical factors. A well controlled study taking these factors into account with several different building materials, is thus recommended to further study whether the observed results have practical significance. These experiments should be carried out under realistic fullscale conditions. (au)

A review of air exchange rate models for air pollution exposure assessments.

Science.gov (United States)

Breen, Michael S; Schultz, Bradley D; Sohn, Michael D; Long, Thomas; Langstaff, John; Williams, Ronald; Isaacs, Kristin; Meng, Qing Yu; Stallings, Casson; Smith, Luther

2014-11-01

A critical aspect of air pollution exposure assessments is estimation of the air exchange rate (AER) for various buildings where people spend their time. The AER, which is the rate of exchange of indoor air with outdoor air, is an important determinant for entry of outdoor air pollutants and for removal of indoor-emitted air pollutants. This paper presents an overview and critical analysis of the scientific literature on empirical and physically based AER models for residential and commercial buildings; the models highlighted here are feasible for exposure assessments as extensive inputs are not required. Models are included for the three types of airflows that can occur across building envelopes: leakage, natural ventilation, and mechanical ventilation. Guidance is provided to select the preferable AER model based on available data, desired temporal resolution, types of airflows, and types of buildings included in the exposure assessment. For exposure assessments with some limited building leakage or AER measurements, strategies are described to reduce AER model uncertainty. This review will facilitate the selection of AER models in support of air pollution exposure assessments.

24 CFR 3280.710 - Venting, ventilation and combustion air.

Science.gov (United States)

2010-04-01

... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air systems...

Ventilation, indoor air quality, and health in homes undergoing weatherization.

Science.gov (United States)

Francisco, P W; Jacobs, D E; Targos, L; Dixon, S L; Breysse, J; Rose, W; Cali, S

2017-03-01

Ventilation standards, health, and indoor air quality have not been adequately examined for residential weatherization. This randomized trial showed how ASHRAE 62-1989 (n=39 houses) and ASHRAE 62.2-2010 (n=42 houses) influenced ventilation rates, moisture balance, indoor air quality, and self-reported physical and mental health outcomes. Average total airflow was nearly twice as high for ASHRAE 62.2-2010 (79 vs. 39 cfm). Volatile organic compounds, formaldehyde and carbon dioxide were all significantly reduced for the newer standard and first-floor radon was marginally lower, but for the older standard, only formaldehyde significantly decreased. Humidity in the ASHRAE 62.2-2010 group was only about half that of the ASHRAE 62-1989 group using the moisture balance metric. Radon was higher in the basement but lower on the first floor for ASHRAE 62.2-2010. Children in each group had fewer headaches, eczema, and skin allergies after weatherization and adults had improvements in psychological distress. Indoor air quality and health improve when weatherization is accompanied by an ASHRAE residential ventilation standard, and the 2010 ASHRAE standard has greater improvements in certain outcomes compared to the 1989 standard. Weatherization, home repair, and energy conservation projects should use the newer ASHRAE standard to improve indoor air quality and health. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The effect of time-dependent ventilation and radon (thoron) gas emanation rates in underground uranium mines

International Nuclear Information System (INIS)

Bigu, J.

1987-01-01

A theoretical radiation mine model, suitable for underground uranium mines, has been investigated. In this model, the rate of ventilation and/or the radon (thoron) gas emanation from mine walls are time-dependent. Several cases of practical interest have been investigated including sinusoidal, linear, exponential, stepwise, or a combination of two or more of the above. Analytical solutions were obtained for the time-dependent radon (thoron) gas emanation rate. However, because of the extreme analytical complexity of the solutions corresponding to the time-dependent ventilation rate case, numerical solutions were found using a special Runge-Kutta procedure and the Hamming's modified predictor-corrector method for the solution of linear initial-value problems. The mine model makes provisions for losses of radioactivity, other than by ventilation and radioactive decay, by, say, plate-out on mine walls, and by other mechanisms. Radioactivity data, i.e., radon, thoron, and their progeny, obtained with the above mine model for a number of ventilation and emanation conditions, are presented. Experimental data obtained in an inactive stope of an underground uranium mine for a time-dependent air flow case are shown. Air flow conditions (ventilation rate) were determined by tracer gas techniques using SF 6

The air quality in ventilation installations. Practical guidelines; Qualite de l'air dans les installations aerauliques. Guide pratique

Energy Technology Data Exchange (ETDEWEB)

Angeli, L. [France Air, 91 - Chilly Mazarin (France); Bianchina, M. [Unelvent, 93 - Le Bourget (France); Blazy, M. [Anjos, 01 - Torcieu (France); Boulanger, X. [Aldes, 21 - Chenove (France); Chiesa, M. [Atlantic (France); Duclos, M. [Groupe Titanair, 69 - Lyon (France); Hubert, D.; Kridorian, O. [Groupe Astato, Blanc Mesnil (France); Josserand, O. [Carrier (Belgium); Lancieux, C. [Camfil, 60 - Saint Martin Longueau (France); Lemaire, J.C. [Agence de l' Environnement et de la Maitrise de l' Energie, ADEME, 75 - Paris (France); Petit, Ph. [Compagnie Industrielle d' Applications Thermiques ( CIAT ), 75 - Paris (France); Ribot, B. [Electricite de France (EDF), 75 - Paris (France); Tokarek, S. [Gaz de France (GDF), 75 - Paris (France); Bernard, A.M.; Tissot, A. [Centre Technique des Industries Aerauliques et Thermiques (CETIAT), 69 - Villeurbanne (France)

2004-07-01

The present guide aims to provide design departments, maintenance companies and builders with practical guidelines and recommendations for the installation of ventilation and air-conditioning systems. The objective is to ensure good Indoor Air Quality (IAQ) and to safeguard the health and well-being of the occupants. The guide deals with aspects of design, dimensioning, installation and servicing, all of which play a major role in guaranteeing IAQ and duct-work hygiene. These steps are reviewed for the principal ventilation systems met in both residential and commercial premises. The first part presents the system and draws the attention of the user to specific points which require particular care in term of IAQ. The second part details recommended practice component by component, in respect of design, installation and servicing. Application of these simple guidelines during the various project stages is essential, in order to ensure a good IAQ in ventilation systems. Content: introduction; good ventilation; systems: exhaust ventilation, balanced ventilation, air handling unit, terminal ventilation units, impact of systems on indoor air quality, components: air inlet, air filter, heat recovery unit, heating or cooling coil, humidifier, mechanical fan unit, cowl and hybrid ventilation fan, mixing box, ventilation duct-work, air outlet and air terminal device; references.

Heating, ventilating, and air-conditioning applications

International Nuclear Information System (INIS)

Anon.

1991-01-01

This book covers: Comfort air conditioning and heating of residences: Space HVAC systems; Industrial and special air conditioning and ventilation for nuclear facilities, and for mines; Energy sources, such as Geothermal energy, solar utilization, and energy resources; Building operation and maintenance; energy management, and Thermal storage

Experimental analysis of indoor air quality improvement achieved by using a Clean-Air Heat Pump (CAHP) air-cleaner in a ventilation system

DEFF Research Database (Denmark)

Sheng, Ying; Fang, Lei; Nie, Jinzhe

2017-01-01

This study investigated the air purification effect of a Clean-Air Heat Pump (CAHP) air-cleaner which combined a silica gel rotor with a heat pump to achieve air cleaning, heating and ventilation in buildings. The experiments were conducted in a field laboratory and compared a low outdoor air...... supply rate with CAHP air purification of recirculated air with three different outdoor air supply rates without recirculation or air cleaning. Sensory assessments of perceived air quality and chemical measurements of TVOC concentration were used to evaluate the air-cleaning performance of the CAHP....... The results of the experiment showed that the operation of the CAHP significantly improved the perceived air quality in a room polluted by both human bio-effluents and building materials. At the outdoor airflow rate of 2 L/s per person, the indoor air quality with CAHP was equivalent to what was achieved...

Heating, Ventilation and Air-Conditioning Systems, Part of Indoor Air Quality Design Tools for Schools

Science.gov (United States)

The main purposes of a Heating, Ventilation, and Air-Conditioning system are to help maintain good indoor air quality through adequate ventilation with filtration and provide thermal comfort. HVAC systems are among the largest energy consumers in schools.

Personalized ventilation: evaluation of different air terminal devices

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Cermak, Radim; Majer, M.

2002-01-01

Personalized ventilation (PV) aims to provide clean air to the breathing zone of occupants. Its performance depends to a large extent on the supply air terminal device (ATD). Five different ATDs were developed, tested and compared. A typical office workplace consisting of a desk with mounted ATDs...... was simulated in a climate chamber. A breathing thermal manikin was used to simulate a human being. Experiments at room air temperatures of 26 and 20 deg.C and personalized air temperatures of 20 deg.C supplied from the ATDs were performed. The flow rate of personalized air was changed from less than 5 up to 23...... l/s. Tracer gas was used to identify the amount of personalized air inhaled by the manikin as well as the amount of exhaled air re-inhaled. The heat loss from the body segments of the thermal manikin was measured and used to calculate the equivalent temperature for the whole body as well as segments...

Demand controlled ventilation in a bathroom

DEFF Research Database (Denmark)

Mortensen, Dorthe Kragsig; Nielsen, Toke Rammer; Topp, Claus

2008-01-01

consumption during periods where the demand for ventilation is low and poor indoor climate during periods where the demand for ventilation is high. Controlling the ventilation rate by demand can improve the energy performance of the ventilation system and the indoor climate. This paper compares the indoor...... climate and energy consumption of a Constant Air Volume (CAV) system and a Demand Controlled Ventilation (DCV) system for two different bathroom designs. The air change rate of the CAV system corresponded to 0.5h-1. The ventilation rate of the DCV system was controlled by occupancy and by the relative...

Ventilation System Type and the Resulting Classroom Temperature and Air Quality During Heating Season

DEFF Research Database (Denmark)

Gao, Jie; Wargocki, Pawel; Wang, Yi

2014-01-01

The present study investigated how different ventilation system types influence classroom temperature and air quality. Five classrooms were selected in the same school. They were ventilated by manually operable windows, manually operable windows with exhaust fan, automatically operable windows...... with and without exhaust fan and by mechanical ventilation system. Temperature, relative humidity, carbon dioxide (CO2) concentration and opening of windows were continuously monitored for one month during heating season in 2012. Classroom with manually operable windows had the highest carbon dioxide concentration...... levels so that the estimated ventilation rate was the lowest compared with the classrooms ventilated with other systems. Temperatures were slightly lower in classroom ventilated by manually operable windows with exhaust fan. Windows were opened seldom even in the classroom ventilated by manually operable...

Healthy Zero Energy Buildings (HZEB) Program - Cross-Sectional Study of Contaminant Levels, Source, Strengths, and Ventilation Rates in Retail Stores

Energy Technology Data Exchange (ETDEWEB)

Chan, Wanyu R.; Sidheswaran, Meera; Cohn, Sebastian; Sullivan, Douglas P.; Fisk, William

2014-02-01

This field study measured ventilation rates and indoor air quality parameters in 21 visits to retail stores in California. The data was collected to guide the development of new, science-based commercial building ventilation rate standards that balance the dual objectives of increasing energy efficiency and maintaining acceptable indoor air quality. Data collection occurred between September 2011 and March 2013. Three types of stores participated in this study: grocery stores, furniture/hardware stores, and apparel stores. Ventilation rates and indoor air contaminant concentrations were measured on a weekday, typically between 9 am and 6 pm. Ventilation rates measured using a tracer gas decay method exceeded the minimum requirement of California’s Title 24 Standard in all but one store. Even though there was adequate ventilation according to Title 24, concentrations of formaldehyde, acetaldehyde, and acrolein exceeded the most stringent chronic health guidelines. Other indoor air contaminants measured included carbon dioxide (CO{sub 2}), carbon monoxide (CO), ozone (O{sub 3}), and particulate matter (PM). Concentrations of CO{sub 2} were kept low by adequate ventilation, and were assumed low also because the sampling occurred on a weekday when retail stores were less busy. CO concentrations were also low. The indoor-outdoor ratios of O{sub 3} showed that the first-order loss rate may vary by store trade types and also by ventilation mode (mechanical versus natural). Analysis of fine and ultrafine PM measurements showed that a substantial portion of the particle mass in grocery stores with cooking-related emissions was in particles less than 0.3 μm. Stores without cooking as an indoor source had PM size distributions that were more similar indoors and outdoors. The whole-building emission rates of volatile organic compounds (VOCs) and PM were estimated from the measured ventilation rates and indoor and outdoor contaminant concentrations. Mass balance models were

Reduced exposure to coughed air by a novel ventilation method for hospital patient rooms

DEFF Research Database (Denmark)

Bolashikov, Zhecho Dimitrov; Melikov, Arsen Krikor; Brand, Marek

2012-01-01

A novel hospital bed integrated ventilation and cleaning unit (HBIVCU) for local airflow control and cleansing, limiting the airborne spread of contagious air coughed from a sick patient in a hospital room, was developed. The performance efficiency of the unit, to successfully reduce occupants......’ exposure to coughed air, was studied in a full-scale, two-bed hospital room mock-up, 4.65 m x 4.65 m x 2.60 m (W x L x H), with two patients and a doctor. Four units were placed along the two sides of both beds close to the head. The room was ventilated by overhead mixing air distribution at 22 °C room air...... of the novel unit, at background ventilation rates of 3 h-1and 6 h-1, was evaluated by measuring the excess CO2 concentration at the mouth of both the doctor and the exposed patient. When the novel method was not used, the CO2 concentration (exposure) measured in the air “inhaled” by the doctor exceeded 20...

Air-conditioning and ventilation systems and components of nuclear facilities

International Nuclear Information System (INIS)

2006-01-01

The Guide defines the requirements for the design, implementation and operation of the air-conditioning and ventilation systems of nuclear facilities belonging to safety classes 3 and 4, and for the related documents to be submitted to STUK (Radiation and Nuclear Safety Authority, Finland). Furthermore, the Guide describes the inspections of air-conditioning and ventilation systems to be conducted by STUK during construction and operation of the facilities. As far as systems and components belonging to safety class 2 are concerned, STUK sets additional requirements case by case. In general, air-conditioning systems refer to systems designed to manage the indoor air cleanness, temperature, humidity and movement. In some rooms of a nuclear power plant, ventilation systems are also used to prevent radioactive materials from spreading outside the rooms. Guide YVL1.0 defines the safety principles concerning the air-conditioning and ventilation of nuclear power plants. Guide YVL2.0 gives the requirements for the design of nuclear power plant systems. In addition, YVLGuide groups 3, 4, 5 and 7 deal with the requirements for air-conditioning and ventilation systems with regard to the mechanical equipment, fire prevention, electrical systems, instrumentation and control technology, and the restriction of releases. The rules and regulations issued by the Ministry of the Environment and the Ministry of the Interior (RakMK, the Finnish building code) concerning the design and operation of air-conditioning and ventilation systems and the related fire protection design bases also apply to nuclear facilities. Exhaust gas treatment systems, condenser vacuum systems of boiling water reactor plants and leak collection systems are excluded from the scope of this Guide

Ventilation and air heating systems. 5. rev. and enlarged ed. Lueftung und Luftheizung

Energy Technology Data Exchange (ETDEWEB)

Ihle, C. (Bundesfachschule fuer Sanitaer-, Heizungs- und Klimatechnik, Karlsruhe (Germany))

1991-01-01

Higher demands on the air quality of flats, offices and assembly rooms make ventilation and air heating the subjects of increasing interest. Taking into account the ever more urgent need for energy conservation the book deals with all aspects of ventilation on the basis of the recent DIN standards, VDI sheets and regulations. It may be used as an instruction manual, professional reference book or as a guide to practice-oriented subject selection with a minimum of theoretical fundamentals. The book deals with ventilation and air heating systems, free ventilation, design fundamentals, exercised for ventilation and air heating systems, central and decentralized ventilation systems, practical examples, ducts and calculation of ducts, air distribution, fans, noise formation, noise pollution abatement and heat recovery. (BWI) With 472 figs., 91 tabs., 1 separate map.

The results of air treatment process modeling at the location of the air curtain in the air suppliers and ventilation shafts

Directory of Open Access Journals (Sweden)

Nikolaev Aleksandr

2017-01-01

Full Text Available In the existing shaft air heater installations (AHI, that heat the air for air suppliers in cold seasons, a heater channel is used. Some parts of the air from the heater go to the channel, other parts are sucked through a pithead by the general shaft pressure drawdown formed by the main ventilation installation (MVI. When this happens, a mix of two air flows leads to a shaft heat regime violation that can break pressurization of intertubular sealers. The problem of energy saving while airing underground mining enterprises is also very important. The proposed solution of both tasks due to the application of an air curtain is described in the article. In cold seasons the air treatment process should be used and it is offered to place an air curtain in the air suppliers shaft above the place of interface of the calorifer channel to a trunk in order to avoid an infiltration (suction of air through the pithead. It’s recommended to use an air curtain in a ventilation shaft because it reduces external air leaks thereby improving energy efficiency of the MVI work. During the mathematical modeling of ventilation and air preparation process (in SolidWorks Flowsimulation software package it was found out that the use of the air curtain in the air supply shaft can increase the efficiency of the AHI, and reduce the electricity consumption for ventilation in the ventilation shaft.

Thermal comfort and ventilation effectiveness in an office room with radiant floor cooling and displacement ventilation

DEFF Research Database (Denmark)

Krajcik, Michal; Tomasi, Roberta; Simone, Angela

2016-01-01

conditions, varying the nominal air change rate from 4.5h-1 down to 1.5h-1. Contaminant removal and mean-age-of-air measurements were performed to characterize the ventilation effectiveness and air velocity; air and operative temperature profiles were measured, together with thermal manikin equivalent...... temperatures, to evaluate the thermal environment. The combined system was able to achieve good ventilation effectiveness close to a heat source, so that in the occupant's breathing zone the ventilation effectiveness was significantly better than for ideal mixing, even at a nominal air change rate as low as 1......% at the highest nominal air change rate of 4.5h-1, even for an occupant sitting 1 meter in front of the supply diffuser, the local thermal discomfort occasioned by the excessive vertical temperature differences gives chilled ceilings the advantage over chilled floors for use with displacement ventilation....

Ventilation-air conditioner system in nuclear power plant

International Nuclear Information System (INIS)

Kubota, Ryuji; Sugisaki, Toshihiko.

1989-01-01

This invention concerns a ventilation-air conditioner system which enables, upon occurrence of accidents in a nuclear power plant, continuous operation for other adjacent nuclear power plants with no effect of accidents. Air supply system and exhaust system are operated during usual operaiton. If loss of coolants accidents should occur in an adjacent nuclear power plants, operation is switched from ventilation operaiton to the operation of re-cycling system based on an AND logic of three signals, that is, a pressure HIGH signal for the reactor container, a water level LOW signal for the reactor and a radioactivity signal of the ventilation-air conditioner sytem on the side of air supply in the nuclear power plant. Thus, nuclear reactor buildings of the nuclear power plant are from the external atmosphere. Therefore, the radioactivity HIGH signal for switching to the emergency air conditioner system of the nuclear power plant is not actuated due to the loss of coolant accidents in the adjacent nuclear power plant. In addition, since the atmospheric temperature in the nuclear reactor building can be maintained by a cooling device disposed to the recycling system, reactor shutdown can be prevented. (I.S.)

Ventilation rate in equilibrium factor measurements with solid state nuclear track detectors (SSNTD)

International Nuclear Information System (INIS)

Gil, L.R.; Leitao, R.M.S.; Marques, A.; Rivera, A.

1994-08-01

Ventilation rate values are calculated from track density measurements in solid state nuclear track detectors (SSNTD), both when ventilation is the main cause of radioactive disequilibrium in radon progeny and when it shares importance with other agents. The method consists in exposing a SSNTD of high intrinsic efficiency (CR-39) in filtered and unfiltered conditions and, in addition, covered with a thin Aluminium foil, to stop alpha particles from 218 Po and 222 Rn. No calibrations are required but, when necessary, independent measurements of the loss rates of radioactivity to aerosol and to walls have to perform. Ventilation rates depend upon geometry detection efficiencies for alpha particles, here obtained by Monte Carlo simulation, taking into account the space distribution of emission positions. This may lead to sizeable corrections in ventilation and equilibrium factor values. Since geometric detection efficiencies depend upon alpha-particle ranges in air, the influences of barometric variables are also discussed. (author). 7 refs

Sensor-based demand controlled ventilation

Energy Technology Data Exchange (ETDEWEB)

De Almeida, A.T. [Universidade de Coimbra (Portugal). Dep. Eng. Electrotecnica; Fisk, W.J. [Lawrence Berkeley National Lab., CA (United States)

1997-07-01

In most buildings, occupancy and indoor pollutant emission rates vary with time. With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation (i.e., rate of outside air supply) also varies with time to compensate for the changes in pollutant generation. In other words, SBDCV involves the application of sensing, feedback and control to modulate ventilation. Compared to ventilation without feedback, SBDCV offers two potential advantages: (1) better control of indoor pollutant concentrations; and (2) lower energy use and peak energy demand. SBDCV has the potential to improve indoor air quality by increasing the rate of ventilation when indoor pollutant generation rates are high and occupants are present. SBDCV can also save energy by decreasing the rate of ventilation when indoor pollutant generation rates are low or occupants are absent. After providing background information on indoor air quality and ventilation, this report provides a relatively comprehensive discussion of SBDCV. Topics covered in the report include basic principles of SBDCV, sensor technologies, technologies for controlling air flow rates, case studies of SBDCV, application of SBDCV to laboratory buildings, and research needs. SBDCV appears to be an increasingly attractive technology option. Based on the review of literature and theoretical considerations, the application of SBDCV has the potential to be cost-effective in applications with the following characteristics: (a) a single or small number of dominant pollutants, so that ventilation sufficient to control the concentration of the dominant pollutants provides effective control of all other pollutants; (b) large buildings or rooms with unpredictable temporally variable occupancy or pollutant emission; and (c) climates with high heating or cooling loads or locations with expensive energy.

Experimental study of air distribution and ventilation effectiveness in a room heated by warm air and/or floor heating

DEFF Research Database (Denmark)

Simone, Angela; Olesen, Bjarne W.; Krajčík, Michal

2010-01-01

The levels of required ventilation depend on the criteria for indoor air quality in existing standards and guidelines. On top of that, the resulting ventilation in air changes per hour is depending on the ventilation effectiveness. In the standard CR 1752 the recommended values for ventilation ef...

Air compressor battery duration with mechanical ventilation in a field anesthesia machine.

Science.gov (United States)

Szpisjak, Dale F; Giberman, Anthony A

2015-05-01

Compressed air to power field anesthesia machine ventilators may be supplied by air compressor with battery backup. This study determined the battery duration when the compPAC ventilator's air compressor was powered by NiCd battery to ventilate the Vent Aid Training Test Lung modeling high (HC = 0.100 L/cm H2O) and low (LC = 0.020 L/cm H2O) pulmonary compliance. Target tidal volumes (VT) were 500, 750, and 1,000 mL. Respiratory rate = 10 bpm, inspiratory-to-expiratory time ratio = 1:2, and fresh gas flow = 1 L/min air. N = 5 in each group. Control limits were determined from the first 150 minutes of battery power for each run and lower control limit = mean VT - 3SD. Battery depletion occurred when VT was below the lower control limit. Battery duration ranged from 185.8 (±3.2) minutes in the LC-1000 group to 233.3 (±3.6) minutes in the HC-750 group. Battery duration of the LC-1000 group was less than all others (p = 0.027). The differences among the non-LC-1000 groups were not clinically significant. Reprint & Copyright © 2015 Association of Military Surgeons of the U.S.

Influence of ventilation structure on air flow distribution of large turbo-generator

Science.gov (United States)

Zhang, Liying; Ding, Shuye; Zhao, Zhijun; Yang, Jingmo

2018-04-01

For the 350 MW air - cooled turbo—generator, the rotor body is ventilated by sub -slots and 94 radial ventilation ducts and the end adopts arc segment and the straight section to acquire the wind. The stator is ventilated with five inlets and eight outlet air branches. In order to analyze the cooling effect of different ventilation schemes, a global physical model including the stator, rotor, casing and fan is established, and the assumptions and boundary conditions of the solution domain are given. the finite volume method is used to solve the problem, and the air flow distribution characteristics of each part of the motor under different ventilation schemes are obtained. The results show that the baffle at the end of the rotor can eliminate the eddy current at the end of the rotor, and make the flow distribution of cooling air more uniform and reasonable. The conclusions can provide reference for the design of motor ventilation structure.

Heart rate and leukocytes after air and ground transportation in artificially ventilated neonates: a prospective observational study.

Science.gov (United States)

Grosek, Stefan; Mlakar, Gorazd; Vidmar, Ivan; Ihan, Alojz; Primozic, Janez

2009-01-01

To evaluate the effect of interhospital air and ground transportation of artificially ventilated neonates on heart rate and peripheral blood leukocyte counts. Prospective, observational study. Level III multidisciplinary Neonatal and Pediatric Intensive Care Unit. Fifty-eight near-term artificially ventilated transported neonates between May 2006 and April 2007. Day-helicopter, day- and night-ground transportation. Heart rate at retrieval, on admission to the ICU and 1 h later, and peripheral blood leukocyte counts on admission and 1 d later were compared. Fifteen neonates were transported by helicopter during the daytime (D-HEL), 20 by daytime ground and 23 by nighttime ground transportation (D-GROUND, N-GROUND). No differences in delivery mode, birth weight, gestational age, gender, primary diagnoses for transportation, response time and duration of transportation were found between the groups. Similarly, no differences in pH, pCO(2), blood pressure and skin temperature at retrieval and on admission to the ICU were found between the three groups. The mean heart rate at retrieval did not differ significantly, while on arrival in the ICU and 1 h later the D-GROUND group of patients showed a significantly higher mean heart rate compared to the D-HEL and N-GROUND groups. Moreover, leukocyte counts on arrival in the ICU showed significantly higher leukocyte counts in the D-GROUND group of patients compared to the D-HEL group of patients. These results demonstrate that there is an association between daytime ground transportation and higher heart rate and peripheral blood leukocytes.

Instrumentation strategies for energy conservation in broiler barns with ventilation air solar pre-heaters

Energy Technology Data Exchange (ETDEWEB)

Cordeau, Sebastien; Barrington, Suzelle [Department of Bioresource Engineering, Macdonald Campus of McGill University, 21 111 Lakeshore, Ste Anne de Bellevue, Quebec H9X 3V9 (Canada)

2010-08-15

At the present consumption rate, world fossil-fuel reserves are expected to be depleted by 2050 unless their consumption is optimized and supplemented with renewable energy sources. The objective of this project was to evaluate the performance of a simple data acquisition system installed to conduct an energy balance and identify energy saving strategies in two commercial broilers barns with ventilation air solar pre-heaters. Located near Montreal, Canada, the two identical barns were instrumented for inside and outside air conditions, ventilation rate and energy recovery by the solar air pre-heaters. Whereas the temperature, relative humidity and radiation sensors were reliable, inside air temperature stratification complicated energy balance analyses and broiler heat production rate calculations. Lack of room air mixing resulted in the loss of 25 and 15% of the generated heater load and recovered solar energy. The proper monitoring of all environmental conditions required their measurement every 5 rather than 20 min. Instead of using a data transmission service found to be unreliable in rural areas, all data loggers were downloaded onto a portable computer every 45 days during regular instrument maintenance. Accordingly, room air mixing is recommended to facilitate energy balance studies and improve the efficient use of heating energies. (author)

A simplified model for estimating population-scale energy impacts of building envelope air-tightening and mechanical ventilation retrofits

Energy Technology Data Exchange (ETDEWEB)

Logue, Jennifer M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Turner, William J. N. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Trinity College Dublin, Dublin (Ireland); Walker, Iain S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Singer, Brett C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2015-01-19

Changing the air exchange rate of a home (the sum of the infiltration and mechanical ventilation airflow rates) affects the annual thermal conditioning energy. Large-scale changes to air exchange rates of the housing stock can significantly alter the residential sector's energy consumption. However, the complexity of existing residential energy models is a barrier to the accurate quantification of the impact of policy changes on a state or national level. The Incremental Ventilation Energy (IVE) model developed in this study combines the output of simple air exchange models with a limited set of housing characteristics to estimate the associated change in energy demand of homes. The IVE model was designed specifically to enable modellers to use existing databases of housing characteristics to determine the impact of ventilation policy change on a population scale. The IVE model estimates of energy change when applied to US homes with limited parameterisation are shown to be comparable to the estimates of a well-validated, complex residential energy model.

Experimental Investigation of Heat Transfer during Night-Time Ventilation

DEFF Research Database (Denmark)

Artmann, Nikolai; Jensen, Rasmus Lund; Manz, H.

2010-01-01

is the heat transfer at the internal room surfaces. Increased convection is expected due to high air flow rates and the possibility of a cold air jet flowing along the ceiling, but the magnitude of these effects is hard to predict. In order to improve the predictability, heat transfer during night......-time ventilation in case of mixing and displacement ventilation has been investigated in a full scale test room. The results show that for low air flow rates displacement ventilation is more efficient than mixing ventilation. For higher air flow rates the air jet flowing along the ceiling has a significant effect...

Numerical simulation of ventilation air movement in partitioned offices

Energy Technology Data Exchange (ETDEWEB)

Plett, E.G.; Soultogiannis, A.A.; Jouini, D.B. (Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa, Ontario (Canada))

1993-01-01

Good air quality can only be assured throughout an office complex if each workspace receives an adequate supply of ventilation air. The likelihood of achieving this situation would be increased if the building engineer had a means of easily predicting the air movement in each office configuration. A simple computer-based solution to this need is proposed. To this end, the development and validation testing of a numerical solution technique to simulate the ventilation air movement in a room or office is described. The predictions of the two-dimensional, isothermal, inviscid formulation are seen to be in good agreement with experimentally measured airflows in configurations of interest. The computer code is then used to illustrate the airflow in offices served by a single row of supply air diffusers, when partitions are used to divide the space into smaller workspaces. It is observed that the partitions distort the airflow patterns to the extent that it would be difficult to provide desirable ventilation airflows to all the workspaces formed by the partitions. (au) (26 refs.)

Perceived Air Quality in a Displacement Ventilated Room

DEFF Research Database (Denmark)

Brohus, Henrik; Knudsen, Henrik Nellemose; Nielsen, Peter V.

in a displacement ventilated room was determined directly by asking humans about how they perceived the air quality. A trained sensory panel comprising 12 subjects assessed the perceived air quality immediately after entering a climate chamber. The experiments showed that the perceived air quality...

Technical Note: A proposal of air ventilation system design criteria for a clinical room in a heavy-ion medical facility.

Science.gov (United States)

Kum, Oyeon

2018-04-16

An optimized air ventilation system design for a treatment room in Heavy-ion Medical Facility is an important issue in the aspects of nuclear safety because the activated air produced in a treatment room can directly affect the medical staff and the general public in the radiation-free area. Optimized design criteria of air ventilation system for a clinical room in 430 MeV/u carbon ion beam medical accelerator facility was performed by using a combination of MCNPX2.7.0 and CINDER'90 codes. Effective dose rate and its accumulated effective dose by inhalation and residual gamma were calculated for a normal treatment scenario (2 min irradiation for one fraction) as a function of decay time. Natural doses around the site were measured before construction and used as reference data. With no air ventilation system, the maximum effective dose rate was about 3 μSv/h (total dose of 90 mSv/y) and minimum 0.2 μSv/h (total dose of 6 mSv/y), which are over the legal limits for medical staff and for the general public. Although inhalation dose contribution was relatively small, it was considered seriously because of its long-lasting effects in the body. The integrated dose per year was 1.8 mSv/y in the radiation-free area with the 20-min rate of air ventilation system. An optimal air ventilation rate of 20 min is proposed for a clinical room, which also agrees with the best mechanical design value. © 2018 American Association of Physicists in Medicine.

Demand controlled ventilation in single-family homes; Behovstyret ventilation til enfamiliehuse

Energy Technology Data Exchange (ETDEWEB)

Rammer Nielsen, T.; Drivsholm, C.; Rudolph Hansen, M.P.; Kragh, J.

2009-12-15

This project investigated two different control strategies: A simple and cheap strategy and an advanced and expensive strategy: 1. Simple control: The ventilation rate is varied only on the whole building level giving an average ventilation rate of either 0.1 l/(s m{sup 2}) or 0.35 l/(s m{sup 2}). The air change rate is controlled by sensors in the air handling unit measuring relative humidity, temperature and CO{sub 2}. The control is based on the CO{sub 2}-concentration and absolute humidity in the supply air and exhaust air. A fixed set point for the difference in CO{sub 2}-concentration between the exhaust and supply is used to decide if the ventilation rate is low or high. As supplement to the CO{sub 2} control the difference in absolute humidity between exhaust and supply is used to assure that the ventilation remain at the high level if there is a high level of humidity in the house. 2. Advanced control: The air change rate is varied dynamically for all living rooms giving an average air change for the house between 0.1 l/(s m{sup 2}) and 0.35 l/(s m{sup 2}). The air change rate in the living rooms is controlled by CO{sub 2}-sensors in each room and dampers in the room supply duct. Relative humidity is measured in the rooms with high moisture production to ensure that the highest air exchange is activated if the relative humidity in one of these rooms is too high. Even though the two strategies have been implemented and tested for a long period of time, only the simple control can be recommended. The simple control ensures that the air quality is almost the same as if the house was ventilated constantly at the high ventilation rate. Also the simple control only requires two CO{sub 2} sensors, two relative humidity sensors and two temperature sensors in the air handling unit. These sensors should be checked from time to time e.g. when filters are exchanged. The simple control is today used in meeting rooms, office rooms and daycare facilities in a modified

CLEAN-AIR heat pump. Reduced energy consumption for ventilation in buildings by integrating air cleaning and heat pump. Final Report; CLEAN-AIR heat pump - Reduceret energiforbrug til ventilation af bygninger ved luftrensning integreret med luft varmepumpe. Slut rapport

Energy Technology Data Exchange (ETDEWEB)

Fang, L.; Olesen, Bjarne W.; Molinaro, G.; Simmonsen, P.; Skocajic, S. [Danmarks Tekniske Univ. Institut for Byggeri og Anlaeg, Lyngby (Denmark); Hummelshoej, R.M.; Carlassara, L. [COWI A/S, Lyngby, (Denmark); Groenbaek, H.; Hansen, Ole R. [Exhausto A/S, Langeskov (Denmark)

2011-07-01

This report summarizes task 1 of the Clean Air Heat Pump project - modelling and simulation on energy savings when using the clean air heat pump for ventilation, air cleaning and energy recovery. The total energy consumption of the proposed ventilation systems using clean air heat pump technology was calculated by a theoretical model and compared with the reference ventilation systems (conventional ventilation systems). The energy compared between the two systems includes energy used for heating, cooling and fan. The simulation and energy saving calculation was made for the application of the clean air heat pump in three typical climate conditions, i.e. mild-cold, mild-hot and hot and wet climates. Real climate data recorded from three cities in 2002 was used for the calculation. The three cities were Copenhagen (Denmark), Milan (Italy) and Colombo (Sir Lanka) which represent the above three typical climate zones. For the Danish climate (the mild cold climate), the calculations show that the ventilation system using clean air heat pump technology can save up to 42% of energy cost in winter compared to the conventional ventilation system. The energy saving in summer can be as high as 66% for the ventilation system with humidity control and 9% for the ventilation system without the requirement of humidity control. Since the Danish summer climate is very mild, over 80% of the yearly energy consumption for ventilation is used during winter season. It is, therefore, estimated that more than 35% annual energy saving for ventilation is expected in Denmark using the clean air heat pump ventilation technology. For the mild hot climate, e.g. the Italian climate, the calculations show that up to 63% of the energy saving can be achieved in summer season. For the winter mode, 17% reduction of the energy cost can be expected for the domestic use. For industrial use, the energy cost of the clean air heat pump may not be favourable due to the industrial price of gas in Italy is

Symptoms and perceived indoor air quality among occupants of houses and apartments with different ventilation systems

Energy Technology Data Exchange (ETDEWEB)

Ruotsalainen, R.; Roennberg, R.; Majanen, A.; Seppaenen, O. (Laboratory of Heating, Ventilating and Air Conditioning, Helsinki University of Technology, Espoo (Finland)); Jaakkola, J.J.K. (Laboratory of Heating, Ventilating and Air Conditioning, Helsinki University of Technology, Espoo (Finland) Department of Public Health, University of Helsinki (Finland))

1991-01-01

The purpose of the study was to evaluate the occurrence of symptoms and the perception of poor indoor air quality among the occupants of houses and apartments with different ventilation systems. The study population consisted of the 473 occupants of 242 dwellings in the Helsinki metropolitan area who responded to a self-administered questionnaire (response rate 93.1%) after a two-week period of indoor air quality measurements. The symptoms of interest were those often related to poor indoor air quality including dryness or itching of the skin; dryness, irritation or itching of the eyes; nasal congestion (''blocked nose''); nasal dryness; nasal discharge (''runny nose''); sneezing; cough; breathlessness; headache or migraine; and lethargy, weakness or nausea. Perception of coldness; warmness; draught; dryness; stuffiness; and sufficiency of air exchange was also requested. The age-standardized period prevalences of the symptoms and complaints were systematically more common among the occupants of the apartments than those of the houses. The occupants of the houses with natural ventilation seemed to have more symptoms and complaints than those with balanced ventilation. However, in the apartments with blanced ventilation the occupants reported, in general, more symptoms and complaints than those with natural ventilation. (au) (9 refs.).

The effect of low ventilation rate with elevated bioeffluent concentration on work performance, perceived indoor air quality, and health symptoms.

Science.gov (United States)

Maula, H; Hongisto, V; Naatula, V; Haapakangas, A; Koskela, H

2017-11-01

The aim of this laboratory experiment was to study the effects of ventilation rate, and related changes in air quality, predominantly bioeffluents, on work performance, perceived indoor air quality, and health symptoms in a typical conditions of modern open-plan office with low material and equipment emissions. In Condition A, outdoor air flow rate of 28.2 l/s person (CO 2 level 540 ppm) was applied and in Condition B, outdoor air flow rate was 2.3 l/s person (CO 2 level 2260 ppm). CO 2 concentration level was used as an indicator of bioeffluents. Performance was measured with seven different tasks which measure different cognitive processes. Thirty-six subjects participated in the experiment. The exposure time was 4 hours. Condition B had a weak negative effect on performance only in the information retrieval tasks. Condition B increased slightly subjective workload and perceived fatigue. No effects on health symptoms were found. The intensity of symptoms was low in both conditions. The experimental condition had an effect on perceived air quality and observed odor intensity only in the beginning of the session. Although the room temperature was controlled in both conditions, the heat was perceived to impair the performance more in Condition B. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Mixing ventilation guide on mixing air distribution design

CERN Document Server

Kandzia, Claudia; Kosonen, Risto; Krikor Melikov, Arsen; Nielsen, Peter Vilhelm

2013-01-01

In this guidebook most of the known and used in practice methods for achieving mixing air distribution are discussed. Mixing ventilation has been applied to many different spaces providing fresh air and thermal comfort to the occupants. Today, a design engineer can choose from large selection of air diffusers and exhaust openings.

[Assessment of the air quality improment of cleaning and disinfection on central air-conditioning ventilation system].

Science.gov (United States)

Liu, Hongliang; Zhang, Lei; Feng, Lihong; Wang, Fei; Xue, Zhiming

2009-09-01

To assess the effect of air quality of cleaning and disinfection on central air-conditioning ventilation systems. 102 air-conditioning ventilation systems in 46 public facilities were sampled and investigated based on Hygienic assessment criterion of cleaning and disinfection of public central air-conditioning systems. Median dust volume decreased from 41.8 g/m2 to 0.4 g/m2, and the percentage of pipes meeting the national standard for dust decreased from 17.3% (13/60) to 100% (62/62). In the dust, median aerobic bacterial count decreased from 14 cfu/cm2 to 1 cfu/cm2. Median aerobic fungus count decreased from 10 cfu/cm2 to 0 cfu/cm2. The percentage of pipes with bacterial and fungus counts meeting the national standard increased from 92.4% (171/185) and 82.2% (152/185) to 99.4% (165/166) and 100% (166/166), respectively. In the ventilation air, median aerobic bacterial count decreased from 756 cfu/m3 to 229 cfu/m3. Median aerobic fungus count decreased from 382 cfu/m3 to 120 cfu/m3. The percentage of pipes meeting the national standard for ventilation air increased from 33.3% (81/243) and 62.1% (151/243) to 79.8% (292/366) and 87.7% (242/276), respectively. But PM10 rose from 0.060 mg/m3 to 0.068 mg/m3, and the percentage of pipes meeting the national standard for PM10 increased from 74.2% (13/60) to 90.2% (46/51). The cleaning and disinfection of central air-conditioning ventilation systems could have a beneficial effect of air quality.

CFD model of air movement in ventilated facade: comparison between natural and forced air flow

Energy Technology Data Exchange (ETDEWEB)

Mora Perez, Miguel; Lopez Patino, Gonzalo; Lopez Jimenez, P. Amparo [Hydraulic and Environmental Engineering Department, Universitat Politècnica de Valencia (Spain)

2013-07-01

This study describes computational fluid dynamics (CFD) modeling of ventilated facade. Ventilated facades are normal facade but it has an extra channel between the concrete wall and the (double skin) facade. Several studies found in the literature are carried out with CFD simulations about the behavior of the thermodynamic phenomena of the double skin facades systems. These studies conclude that the presence of the air gap in the ventilated facade affects the temperature in the building skin, causing a cooling effect, at least in low-rise buildings. One of the most important factors affecting the thermal effects of ventilated facades is the wind velocity. In this contribution, a CFD analysis applied on two different velocity assumptions for air movement in the air gap of a ventilated facade is presented. A comparison is proposed considering natural wind induced velocity with forced fan induced velocity in the gap. Finally, comparing temperatures in the building skin, the differences between both solutions are described determining that, related to the considered boundary conditions, there is a maximum height in which the thermal effect of the induced flow is significantly observed.

Exposure to Exhaled Air from a Sick Occupant in a Two-Bed Hospital Room with Mixing Ventilation: Effect of Posture of Doctor and Air Change Rate

DEFF Research Database (Denmark)

Bolashikov, Zhecho Dimitrov; Melikov, Arsen Krikor; Barova, Mariya

2013-01-01

Full-scale measurements were performed in a climate chamber set as a two-bed hospital room, ventilated at 3, 6 and 12 ACH with overhead mixing ventilation. Air temperature was kept constant at 22 °C. Two breathing thermal manikins were used to mimic a sick patient lying on one side in one of the ...

Quantifying air distribution, ventilation effectiveness and airborne pollutant transport in an aircraft cabin mockup

Science.gov (United States)

Wang, Aijun

The health, safety and comfort of passengers during flight inspired this research into cabin air quality, which is closely related to its airflow distribution, ventilation effectiveness and airborne pollutant transport. The experimental facility is a full-scale aircraft cabin mockup. A volumetric particle tracking velocimetry (VPTV) technique was enhanced by incorporating a self-developed streak recognition algorithm. Two stable recirculation regions, the reverse flows above the seats and the main air jets from the air supply inlets formed the complicated airflow patterns inside the cabin mockup. The primary air flow was parallel to the passenger rows. The small velocity component in the direction of the cabin depth caused less net air exchange between the passenger rows than that parallel to the passenger rows. Different total air supply rate changed the developing behaviors of the main air jets, leading to different local air distribution patterns. Two indices, Local mean age of air and ventilation effectiveness factor (VEF), were measured at five levels of air supply rate and two levels of heating load. Local mean age of air decreased linearly with an increase in the air supply rate, while the VEF remained consistent when the air supply rate varied. The thermal buoyancy force from the thermal plume generated the upside plume flow, opposite to the main jet flow above the boundary seats and thus lowered the local net air exchange. The airborne transport dynamics depends on the distance between the source and the receptors, the relative location of pollutant source, and air supply rate. Exposure risk was significantly reduced with increased distance between source and receptors. Another possible way to decrease the exposure risk was to position the release source close to the exhaust outlets. Increasing the air supply rate could be an effective solution under some emergency situations. The large volume of data regarding the three-dimensional air velocities was

Using a Ventilation Controller to Optimize Residential Passive Ventilation For Energy and Indoor Air Quality

Energy Technology Data Exchange (ETDEWEB)

Turner, William [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Walker, Iain [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2014-08-01

One way to reduce the energy impact of providing residential ventilation is to use passive and hybrid systems. However, these passive and hybrid (sometimes called mixed-mode) systems must still meet chronic and acute health standards for ventilation. This study uses a computer simulation approach to examine the energy and indoor air quality (IAQ) implications of passive and hybrid ventilation systems, in 16 California climate zones. Both uncontrolled and flow controlled passive stacks are assessed. A new hybrid ventilation system is outlined that uses an intelligent ventilation controller to minimise energy use, while ensuring chronic and acute IAQ standards are met. ASHRAE Standard 62.2-2010 – the United States standard for residential ventilation - is used as the chronic standard, and exposure limits for PM_2.5, formaldehyde and NO₂ are used as the acute standards.The results show that controlled passive ventilation and hybrid ventilation can be used in homes to provide equivalent IAQ to continuous mechanical ventilation, for less use of energy.

Modeled effectiveness of ventilation with contaminant control devices on indoor air quality in a swine farrowing facility.

Science.gov (United States)

Anthony, T Renée; Altmaier, Ralph; Park, Jae Hong; Peters, Thomas M

2014-01-01

Because adverse health effects experienced by swine farm workers in concentrated animal feeding operations (CAFOs) have been associated with exposure to dust and gases, efforts to reduce exposures are warranted, particularly in winter seasons when exposures increase due to decreased ventilation. Simulation of air quality and operating costs for ventilating swine CAFO, including treating and recirculating air through a farrowing room, was performed using mass and energy balance equations over a 90-day winter season. System operation required controlling heater operation to achieve room temperatures optimal to ensure animal health (20 to 22.5 °C). Five air pollution control devices, four room ventilation rates, and five recirculation patterns were examined. Inhalable dust concentrations were easily reduced using standard industrial air pollution control devices, including a cyclone, filtration, and electrostatic precipitator. Operating ventilation systems at 0.94 m3 s(-1) (2000 cfm) with 75 to 100% recirculation of treated air from cyclone, electrostatic precipitator, and shaker dust filtration system achieves adequate particle control with operating costs under $1.00 per pig produced ($0.22 to 0.54), although carbon dioxide (CO2) concentrations approach 2000 ppm using in-room ventilated gas fired heaters. In no simulation were CO2 concentrations below industry recommended concentrations (1540 ppm), but alternative heating devices could reduce CO2 to acceptable concentrations. While this investigation does not represent all production swine farrowing barns, which differ in characteristics including room dimensions and swine occupancy, the simulation model and ventilation optimization methods can be applied to other production sites. This work shows that ventilation may be a cost-effective control option in the swine industry to reduce exposures.

INFLUENCE OF APPLYING ADDITIONAL FORCING FANS FOR THE AIR DISTRIBUTION IN VENTILATION NETWORK

Directory of Open Access Journals (Sweden)

Nikodem SZLĄZAK

2016-07-01

Full Text Available Mining progress in underground mines cause the ongoing movement of working areas. Consequently, it becomes neces-sary to adapt the ventilation network of a mine to direct airflow into newly-opened districts. For economic reasons, opening new fields is often achieved via underground workings. Length of primary intake and return routes increases and also increases the total resistance of a complex ventilation network. The development of a subsurface structure can make it necessary to change the air distribution in a ventilation network. Increasing airflow into newly-opened districts is necessary. In mines where extraction does not entail gas-related hazards, there is possibility of implementing a push-pull ventilation system in order to supplement airflows to newly developed mining fields. This is achieved by installing sub-surface fan stations with forcing fans at the bottom of downcast shaft. In push-pull systems with multiple main fans, it is vital to select forcing fans with characteristic curves matching those of the existing exhaust fans to prevent undesirable mutual interaction. In complex ventilation networks it is necessary to calculate distribution of airflow (especially in net-works with a large number of installed fans. In the article the influence of applying additional forcing fans for the air distribution in ventilation network for underground mine were considered. There are also analysed the extent of over-pressure caused by the additional forcing fan in branches of the ventilation network (the operating range of additional forcing fan. Possibilities of increasing airflow rate in working areas were conducted.

Effectiveness of horizontal air flow fans supporting natural ventilation in a Mediterranean multi-span greenhouse

Directory of Open Access Journals (Sweden)

Alejandro López

2013-08-01

Full Text Available Natural ventilation is the most important method of climate control in Mediterranean greenhouses. In this study, the microclimate and air flow inside a Mediterranean greenhouse were evaluated by means of sonic anemometry. Experiments were carried out in conditions of moderate wind (≈ 4.0 m s-1, and at low wind speed (≈ 1.8 m s-1 the natural ventilation of the greenhouse was supplemented by two horizontal air flow fans. The greenhouse is equipped with a single roof vent opening to the windward side and two side vents, the windward one being blocked by another greenhouse close to it, while the leeward one is free of obstacles. When no fans are used, air enters through the roof vent and exits through both side vents, thus flowing contrary to the thermal effect which causes hot air to rise and impairing the natural ventilation of the greenhouse. Using fans inside the greenhouse helps the air to circulate and mix, giving rise to a more homogeneous inside temperature and increasing the average value of normalized air velocity by 365 %. These fans also increase the average values of kinetic turbulence energy inside the greenhouse by 550 % compared to conditions of natural ventilation. As the fans are placed 4 m away from the side vents, their effect on the entrance of outside air is insufficient and they do not help to reduce the inside temperature on hot days with little wind. It is therefore recommended to place the fans closer to the side vents to allow an additional increase of the air exchange rate of greenhouses.

Experimental analysis of fuzzy controlled energy efficient demand controlled ventilation economizer cycle variable air volume air conditioning system

Directory of Open Access Journals (Sweden)

Rajagopalan Parameshwaran

2008-01-01

Full Text Available In the quest for energy conservative building design, there is now a great opportunity for a flexible and sophisticated air conditioning system capable of addressing better thermal comfort, indoor air quality, and energy efficiency, that are strongly desired. The variable refrigerant volume air conditioning system provides considerable energy savings, cost effectiveness and reduced space requirements. Applications of intelligent control like fuzzy logic controller, especially adapted to variable air volume air conditioning systems, have drawn more interest in recent years than classical control systems. An experimental analysis was performed to investigate the inherent operational characteristics of the combined variable refrigerant volume and variable air volume air conditioning systems under fixed ventilation, demand controlled ventilation, and combined demand controlled ventilation and economizer cycle techniques for two seasonal conditions. The test results of the variable refrigerant volume and variable air volume air conditioning system for each techniques are presented. The test results infer that the system controlled by fuzzy logic methodology and operated under the CO2 based mechanical ventilation scheme, effectively yields 37% and 56% per day of average energy-saving in summer and winter conditions, respectively. Based on the experimental results, the fuzzy based combined system can be considered to be an alternative energy efficient air conditioning scheme, having significant energy-saving potential compared to the conventional constant air volume air conditioning system.

Mixing Ventilation. Guide on mixing air distribution design

DEFF Research Database (Denmark)

Kandzia, Claudia; Kosonen, Risto; Melikov, Arsen Krikor

In this guidebook most of the known and used in practice methods for achieving mixing air distribution are discussed. Mixing ventilation has been applied to many different spaces providing fresh air and thermal comfort to the occupants. Today, a design engineer can choose from large selection...

Prototype Systems for Measuring Outdoor Air Intake Rates in Rooftop Air Handlers

Energy Technology Data Exchange (ETDEWEB)

Fisk, William J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Chan, Wanyu R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Hotchi, Toshifumi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2015-01-01

The widespread absence of systems for real-time measurement and feedback control, of minimum outdoor air intake rates in HVAC systems contributes to the poor control of ventilation rates in commercial buildings. Ventilation rates affect building energy consumption and influence occupant health. The project designed fabricated and tested four prototypes of systems for measuring rates of outdoor air intake into roof top air handlers. All prototypes met the ±20% accuracy target at low wind speeds, with all prototypes accurate within approximately ±10% after application of calibration equations. One prototype met the accuracy target without a calibration. With two of four prototype measurement systems, there was no evidence that wind speed or direction affected accuracy; however, winds speeds were generally below usually 3.5 m s^-1 (12.6 km h^-1) and further testing is desirable. The airflow resistance of the prototypes was generally less than 35 Pa at maximum RTU air flow rates. A pressure drop of this magnitude will increase fan energy consumption by approximately 4%. The project did not have resources necessary to estimate costs of mass produced systems. The retail cost of components and materials used to construct prototypes ranged from approximately $1,200 to $1,700. The test data indicate that the basic designs developed in this project, particularly the designs of two of the prototypes, have considerable merit. Further design refinement, testing, and cost analysis would be necessary to fully assess commercial potential. The designs and test results will be communicated to the HVAC manufacturing community.

Analysis of thermal comfort and indoor air quality in a mechanically ventilated theatre

Energy Technology Data Exchange (ETDEWEB)

Kavgic, M.; Mumovic, D.; Young, A. [The Bartlett School of Graduate Studies, University College London, Gower Street, London, WC1E 6BT, England (United Kingdom); Stevanovic, Z. [Institute of Nuclear Sciences - Vinca, P.O. Box 522, 11001 Belgrade (RS)

2008-07-01

Theatres are the most complex of all auditorium structures environmentally. They usually have high heat loads, which are of a transient nature as audiences come and go, and from lighting which changes from scene to scene, and they generally have full or nearly full occupancy. Theatres also need to perform well acoustically, both for the spoken word and for music, and as sound amplification is less used than in other auditoria, background noise control is critically important. All these factors place constraints on the ventilation design, and if this is poor, it can lead to the deterioration of indoor air quality and thermal comfort. To analyse the level of indoor air quality and thermal comfort in a typical medium-sized mechanically ventilated theatre, and to identify where improvements could typically be made, a comprehensive post-occupancy evaluation study was carried out on a theatre in Belgrade. The evaluation, based on the results of monitoring (temperature, relative humidity, CO{sub 2}, air speed and heat flux) and modelling (CFD), as well as the assessment of comfort and health as perceived by occupants, has shown that for most of the monitored period the environmental parameters were within the standard limits of thermal comfort and IAQ. However, two important issues were identified, which should be borne in mind by theatre designers in the future. First, the calculated ventilation rates showed that the theatre was over-ventilated, which will have serious consequences for its energy consumption, and secondly, the displacement ventilation arrangement employed led to higher than expected complaints of cold discomfort, probably due to cold draughts around the occupants' feet. (author)

Relationship between indoor radon concentrations and air exchange rate

International Nuclear Information System (INIS)

Wang Jingshu; Liu Yuyu; Yao Xiaohua; Meng Jianfeng; Zhang Yongyi; Wang Xiaohe; Yu Xiufen.

1995-01-01

The indoor concentration of radon and the air exchange rate were simultaneously measured in four empty rooms, made of brick and cement, which were located in different floors of dwelling houses in Taiyuan, Shanxi, China. SF 6 tracer gas decay method was used to measure the air exchange rate. Indoor radon was collected with the dimembrane method. When the ventilation rate increased, the concentration of radon dropped rapidly. Regression analysis indicated that the indoor concentration of radon was equal to the outdoor level of radon when the air exchange rate was greater than 3-4. SF 6 decay method was an effective and convenient method for measuring the air exchange rate. There was no marked difference in measurements obtained in different locations of a room. (N.K.)

Summary of human responses to ventilation

Energy Technology Data Exchange (ETDEWEB)

Seppanen, Olli A.; Fisk, William J.

2004-06-01

The effects of ventilation on indoor air quality and health is a complex issue. It is known that ventilation is necessary to remove indoor generated pollutants from indoor air or dilute their concentration to acceptable levels. But, as the limit values of all pollutants are not known, the exact determination of required ventilation rates based on pollutant concentrations and associated risks is seldom possible. The selection of ventilation rates has to be based also on epidemiological research (e.g. Seppanen et al., 1999), laboratory and field experiments (e.g. CEN 1996, Wargocki et al., 2002a) and experience (e.g. ECA 2003). Ventilation may also have harmful effects on indoor air quality and climate if not properly designed, installed, maintained and operated as summarized by Seppdnen (2003). Ventilation may bring indoors harmful substances that deteriorate the indoor environment. Ventilation also affects air and moisture flow through the building envelope and may lead to moisture problems that deteriorate the structures of the building. Ventilation changes the pressure differences over the structures of building and may cause or prevent the infiltration of pollutants from structures or adjacent spaces. Ventilation is also in many cases used to control the thermal environment or humidity in buildings. Ventilation can be implemented with various methods which may also affect health (e.g. Seppdnen and Fisk, 2002, Wargocki et al., 2002a). In non residential buildings and hot climates, ventilation is often integrated with air-conditioning which makes the operation of ventilation system more complex. As ventilation is used for many purposes its health effects are also various and complex. This paper summarizes the current knowledge on positive and negative effects of ventilation on health and other human responses. The focus of the paper is on office-type working environment and residential buildings. In the industrial premises the problems of air quality are usually

Constructing a generalized network design model to study air distribution in ventilation networks in subway with a single-track tunnel

Science.gov (United States)

Lugin, IV

2018-03-01

In focus are the features of construction of the generalized design model for the network method to study air distribution in ventilation system in subway with the single-track tunnel. The generalizations, assumptions and simplifications included in the model are specified. The air distribution is calculated with regard to the influence of topology and air resistances of the ventilation network sections. The author studies two variants of the subway line: half-open and closed with dead end on the both sides. It is found that the total air exchange at a subway station depends on the station location within the line. The operating mode of fans remains unaltered in this case. The article shows that elimination of air leakage in the station ventilation room allows an increase in the air flow rate by 7–8% at the same energy consumption by fans. The influence of the stop of a train in the tunnel on the air distribution is illustrated.

An air-conditioning, ventilation and automatic ventilation monitoring and recording system constructed in an unsealed radioisotope laboratory. Energy-saving measures in Nagasaki University Radioisotope Center

International Nuclear Information System (INIS)

Takatsuji, Toshihiro; Yoshida, Masahiro; Takao, Hideaki; Okumura, Yutaka; Ooura, Tosinobu; Kotoura, Kazuki; Yamanaka, Yasushi; Yanagita, Hiroyoshi.

1998-01-01

We constructed an automatic operation system of air-conditioners and ventilators in a radiation controlled area to minimize electric consumption. The system operates the air-conditioner and the ventilator of each ventilation unit when someone is staying in rooms belonging to the unit based on information from an access control system to the controlled area and lighting switches in front of individual room. For understanding of operation conditions and confirmation of radioactive concentration in air lower than the legal limit at the ventilation stack, we also constructed an automatic ventilation monitoring and recording system, which makes complete operation records of each ventilator automatically. These systems enabled to achieve sharp energy-saving compatible with radiation protection. (author)

Simultaneousness of room heating and ventilation air heating

International Nuclear Information System (INIS)

Mathisen, Hans Martin

2006-01-01

The report is part of NTNU-SINTEF's Smart Buildings program, Smart Energy Efficient Buildings (2002-2006), subprogram 3.1 Heating, ventilation and cooling systems. An important part of this subprogram is the development and implementation of heating distribution systems with low return temperature. A comparison has been made of the simultaneousness of room heating and ventilation air heating in six buildings. Existing measuring data with hourly measurements of effect requirements for the different purposes have been employed. Based on the measuring data the relation between the requirements for room heating and ventilation is estimated. A 'fictitious' return temperature has also been estimated. The result shows a significant variation between the buildings. For all there are short periods where the efficiency need for room heating and ventilation is equal (ml)

Thermal comfort and indoor air quality in the lecture room with 4-way cassette air-conditioner and mixing ventilation system

International Nuclear Information System (INIS)

Noh, Kwang-Chul; Jang, Jae-Soo; Oh, Myung-Do

2007-01-01

We performed the experimental and the numerical studies on thermal comfort (TC) and indoor air quality (IAQ) in the lecture room with cooling loads when the operating conditions are changed. Predicted mean vote (PMV) value and CO 2 concentration of the lecture room were measured and compared to the numerical results. Both of them showed a reasonable agreement with each other and then we applied the numerical model to analyze TC and IAQ for a couple of different operating conditions. From the results we found that the increment of the discharge angle of 4-way cassette air-conditioner makes uniformity of TC worse, but rarely affects IAQ. It turned out that TC and IAQ are hardly affected by the variation of the discharge airflow. Finally TC was merely affected by the increment of the ventilation rate, but when the ventilation rate is more than 800m 3 /h, the average CO 2 concentration can be satisfied with the standard limits of Japanese in our case studies. (author)

The influence of opening windows and doors on the natural ventilation rate of a residential building

Science.gov (United States)

An analysis of air exchange rates due to intentional window and door openings in a research test house located in a residential environment is presented. These data inform the development of ventilation rate control strategies as building envelopes are tightened to improve the e...

High Resolution Time Series Cave Ventilation Processes and the Effects on Cave Air Chemistry and Drip Waters: Speleoclimatology and Proxy Calibration

Science.gov (United States)

Kowalczk, A. J.; Froelich, P. N.; Gaffka, C.; Tremaine, D.

2008-12-01

Continuous high resolution (sub-hourly), long-term (Nov 2007-present) monitoring of cave air chemistry (Temperature, Relative Humidity, Barometric Pressure, Radon-222, CO2, Air flow, Wind speed and direction) in a shallow subtropical cave (Hollow Ridge) in N Florida reveals two major ventilation mechanisms: 1) ventilation driven by winds across the cave entrances, and 2) ventilation driven by density differences between atmospheric and cave air. The degree and type of ventilation strongly influence the 222Rn and CO2 of cave air, which in turn affects the timing and extent of calcite deposition in speleothems. The degree of ventilation is estimated using a cave air CO2-δ13CO2 Keeling Plot, or a simple radon deficiency model. Results show cave air has an atmospheric component ranging from 10-90%. During fall and winter, average CO2 (700 ppmv) and 222Rn (50-100 dpm/L) are lower than in spring and summer (CO2 = 1200 ppmv; 222Rn = 1000 dpm/L) due to increased winter ventilation. Decreased ventilation during the summer allows CO2 and 222Rn levels to rise. Winter daily ventilation is primarily a function of density gradients between cave air and atmospheric air, while summer daily ventilation is primarily a function of late morning NW-NE winds above the cave. Stable isotope analyses of drip water (fracture drip and pore flow drip) and aquifer water from Hollow Ridge agree with previous isotope studies of drip water at Florida Caverns State Park, 2 km to the NE. During summer, isotopic composition of pore flow drip water (δ18O -3.8 to -4.0 per mil; δD -17.3 to -20.2 per mil VSMOW) and aquifer water (δ18O -4.0 per mil; δD -18.0 to -21.1 per mil) are similar to average annual weighted isotopic composition of precipitation (δ18O -3.6 per mil) while fracture drip waters (δ18O -3 to -3.4 per mil; δD -11.9 to -14.3 per mil) likely reflect the isotopic composition of individual precipitation events. Pore flow drip waters δ18O are weakly correlated with drip rates

Thermal environment and air quality in office with personalized ventilation combined with chilled ceiling

DEFF Research Database (Denmark)

Lipczynska, Aleksandra; Kaczmarczyk, Jan; Melikov, Arsen Krikor

2015-01-01

The thermal environment and air quality conditions provided with combined system of chilled ceiling and personalized ventilation (PV) were studied in a simulated office room for two occupants. The proposed system was compared with total volume HVAC solutions used today, namely mixing ventilation...... and chilled ceiling combined with mixing ventilation. The objective of the study was to evaluate whether PV can be the only ventilation system in the rooms equipped with chilled ceiling. The room air temperature was 26°C in cases with traditional systems and 28°C when PV was used. PV supplied air...... with the temperature of 25°C. PV improved thermal conditions and was up to nearly 10 times more efficient in delivering clean air at workstations than mixing ventilation systems, which resulted in strong protection of occupants from the cross-infection. In the room space outside workstations no substantial differences...

Experimental and Theoretical Investigation of Impinging Jet Ventilation at Different Cross Sectional Area of Supply Air Duct

Directory of Open Access Journals (Sweden)

Ala'a Abbas Mahdi

2018-03-01

Full Text Available  An experimental and computational analysis of temperature and velocity distribution in an office room have been studied. Office room of dimensions (3m x 1.75m x 3m with two cross sectional types of supply air duct in the experimental part and three different cross sectional types of supply air duct in the theoretical part is usual as a tested model. The RNG k-  turbulence model was employed to solve the governing equations numerically and validated by comparing the numerical results with experimental data. The impinging jet concept has been proposed as a new ventilation strategy for use in office and industrial buildings. The present work focuses on evaluating the performance of a new impinging jet ventilation. In a theoretical study three types of supply air duct are adopted which are square supply air duct (Type-I, semi-elliptic supply air duct (Type-II and rectangle supply air duct (Type-III for two cases of air outlet terminal height from room foot level, 0.14h (case-I & 0.1h (case-II. The third type (rectangle duct gives lowest effective and discomfort conditions when compared with the other two types. This study investigated a number of factors influencing draught discomfort and temperature stratification in an office environment equipped with impinging jet ventilation IJV. The factors considered to be: shape of the air supply device, supply airflow rate and supply air temperature. Acceptable Air Distribution Performance Index (ADPI, effective temperature, and ventilation efficiency obtained that the square cross sectional area of supply air duct at 0.1h (case-II height from foot level gives more acceptable indoor air quality and human thermal comfort when compared with the other types. Also, this type gives good air distribution system not only promotes a comfortable and healthy environment for occupants, but also contributes to energy conservation.

Assessment of Indoor Air Quality Benefits and Energy Costs of Mechanical Ventilation

Energy Technology Data Exchange (ETDEWEB)

Logue, J.M.; Price, P.N.; Sherman, M.H.; Singer, B.C.

2011-07-01

Intake of chemical air pollutants in residences represents an important and substantial health hazard. Sealing homes to reduce air infiltration can save space conditioning energy, but can also increase indoor pollutant concentrations. Mechanical ventilation ensures a minimum amount of outdoor airflow that helps reduce concentrations of indoor emitted pollutants while requiring some energy for fan(s) and thermal conditioning of the added airflow. This work demonstrates a physics based, data driven modeling framework for comparing the costs and benefits of whole-house mechanical ventilation and applied the framework to new California homes. The results indicate that, on a population basis, the health benefits from reduced exposure to indoor pollutants in New California homes are worth the energy costs of adding mechanical ventilation as specified by ASHRAE Standard 62.2.This study determines the health burden for a subset of pollutants in indoor air and the costs and benefits of ASHRAE's mechanical ventilation standard (62.2) for new California homes. Results indicate that, on a population basis, the health benefits of new home mechanical ventilation justify the energy costs.

Modeling ventilation and radon in new dutch dwellings

International Nuclear Information System (INIS)

Janssen, M.P.M.

2003-01-01

Indoor radon concentrations were estimated for various ventilation conditions, the differences being mainly related to the airtightness of the dwelling and the ventilation behavior of its occupants. The estimations were aimed at describing the variation in air change rates and radon concentrations to be expected in the representative newly built Dutch dwellings and identifying the most important parameters determining air change rate and indoor radon concentration. The model estimations were compared with measurements. Most of the air was predicted to enter the model dwelling through leaks in the building shell, independent of the ventilation conditions of the dwelling. Opening the air inlets was shown to be an efficient way to increase infiltration and thus to decrease radon concentration. The effect of increasing the mechanical ventilation rate was considerably less than opening the air inlets. The mechanical ventilation sets the lower limit to the air change rate of the dwelling, and is effective in reducing the radon concentration when natural infiltration is low. Opening inside doors proved to be effective in preventing peak concentrations in poorly ventilated rooms. As the airtightness of newly built dwellings is still being improved, higher radon concentrations are to be expected in the near future and the effect of occupant behavior on indoor radon concentrations is likely to increase. According to the model estimations soil-borne radon played a moderate role, which is in line with measurements. (au)

Air quality in a simulated office environment as a result of reducing pollution sources and increasing ventilation

DEFF Research Database (Denmark)

Wargocki, Pawel; Bako-Biro, Zsolt; Clausen, Geo

2002-01-01

Air quality was studied in an office space classified as low-polluting and ventilated with outdoor air at a rate of 1 h-1. The pollution load in the space was changed by introducing or removing common building-related indoor pollution sources (linoleum, sealant and wooden shelves with books and p...

Interaction of Air Flow in Complex Ventilation Systems

Directory of Open Access Journals (Sweden)

Zhorzh G. Levitskiy

2013-01-01

Full Text Available The article presents the results of study of interaction of air flow in complex ventilation systems. The study used Taylor and Maclaurin’s series and Lagrange formula to create the functional connections on estimation of the impact of changing aerodynamic parameters of one or several simultaneously working regulators on the air flow distribution in mines

Ventilation patterns of the songbird lung/air sac system during different behaviors.

Science.gov (United States)

Mackelprang, Rebecca; Goller, Franz

2013-10-01

Unidirectional, continuous airflow through the avian lung is achieved through an elaborate air sac system with a sequential, posterior to anterior ventilation pattern. This classical model was established through various approaches spanning passively ventilated systems to mass spectrometry analysis of tracer gas flow into various air sacs during spontaneous breathing in restrained ducks. Information on flow patterns in other bird taxa is missing, and these techniques do not permit direct tests of whether the basic flow pattern can change during different behaviors. Here we use thermistors implanted into various locations of the respiratory system to detect small pulses of tracer gas (helium) to reconstruct airflow patterns in quietly breathing and behaving (calling, wing flapping) songbirds (zebra finch and yellow-headed blackbird). The results illustrate that the basic pattern of airflow in these two species is largely consistent with the model. However, two notable differences emerged. First, some tracer gas arrived in the anterior set of air sacs during the inspiration during which it was inhaled, suggesting a more rapid throughput through the lung than previously assumed. Second, differences in ventilation between the two anterior air sacs emerged during calling and wing flapping, indicating that adjustments in the flow pattern occur during dynamic behaviors. It is unclear whether this modulation in ventilation pattern is passive or active. This technique for studying ventilation patterns during dynamic behaviors proves useful for establishing detailed timing of airflow and modulation of ventilation in the avian respiratory system.

Experimental analysis of an air-to-air heat recovery unit for balanced ventilation systems in residential buildings

International Nuclear Information System (INIS)

Fernandez-Seara, Jose; Diz, Ruben; Uhia, Francisco J.; Dopazo, Alberto; Ferro, Jose M.

2011-01-01

This paper deals with the experimental analysis of an air-to-air heat recovery unit equipped with a sensible polymer plate heat exchanger (PHE) for balanced ventilation systems in residential buildings. The PHE is arranged in parallel triangular ducts. An experimental facility was designed to reproduce the typical outdoor and exhaust air conditions with regard to temperature and humidity. The unit was tested under balanced operation conditions, as commonly used in practice. A set of tests was conducted under the reference operating conditions to evaluate the PHE performance. Afterwards, an experimental parametric analysis was conducted to investigate the influence of changing the operating conditions on the PHE performance. Experiments were carried out varying the inlet fresh air temperature, the exhaust air relative humidity and the air flow rate. The experimental results are shown and discussed in this paper.

The role of the U.S. Department of Energy in indoor air quality and building ventilation policy development

Energy Technology Data Exchange (ETDEWEB)

Traynor, G.W. [Lawrence Berkeley Lab., Berkeley, CA (United States). Indoor Environment Program; Talbott, J.M. [U.S. Dept. of Energy, Washington, DC (United States). Office of Building Technologies; Moses, D.O. [U.S. Dept. of Energy, Washington, DC (United States). Office of Environmental Analysis

1993-12-31

Building ventilation consumes about 5.8 exajoules of energy each year in the U.S. The annual cost of this-energy, used for commercial building fans (1.6 exajoules/yr) and the heating and cooling of outside air (4.2 exajoules/yr), is about $US 33 billion per year. Energy conservation measures that reduce heating and cooling season ventilation rates 15 to 35 % in commercial and residential buildings can result in a national savings of about 0.6 to 15 exajoules (doll US 3-8 billion) per year assuming no reduction of commercial building fan energy use. The most significant adverse environmental impact of reduced ventilation and infiltration is the potential degradation of the building`s indoor air quality. Potential benefits to the U.S from the implementation of sound indoor air quality and building ventilation reduction policies include reduced building-sector energy consumption; reduced indoor, outdoor, and global pollution; reduced product costs; reduced worker absenteeism; reduced health care costs; reduced litigation; increased worker well-being and absenteeism; reduced health care costs; reduced litigation; increased productivity; and increased product quality and competitiveness. (author)

Association between substandard classroom ventilation rates and students' academic achievement.

Science.gov (United States)

Haverinen-Shaughnessy, U; Moschandreas, D J; Shaughnessy, R J

2011-04-01

This study focuses on the relationship between classroom ventilation rates and academic achievement. One hundred elementary schools of two school districts in the southwest United States were included in the study. Ventilation rates were estimated from fifth-grade classrooms (one per school) using CO(2) concentrations measured during occupied school days. In addition, standardized test scores and background data related to students in the classrooms studied were obtained from the districts. Of 100 classrooms, 87 had ventilation rates below recommended guidelines based on ASHRAE Standard 62 as of 2004. There is a linear association between classroom ventilation rates and students' academic achievement within the range of 0.9-7.1 l/s per person. For every unit (1 l/s per person) increase in the ventilation rate within that range, the proportion of students passing standardized test (i.e., scoring satisfactory or above) is expected to increase by 2.9% (95%CI 0.9-4.8%) for math and 2.7% (0.5-4.9%) for reading. The linear relationship observed may level off or change direction with higher ventilation rates, but given the limited number of observations, we were unable to test this hypothesis. A larger sample size is needed for estimating the effect of classroom ventilation rates higher than 7.1 l/s per person on academic achievement. The results of this study suggest that increasing the ventilation rates toward recommended guideline ventilation rates in classrooms should translate into improved academic achievement of students. More studies are needed to fully understand the relationships between ventilation rate, other indoor environmental quality parameters, and their effects on students' health and achievement. Achieving the recommended guidelines and pursuing better understanding of the underlying relationships would ultimately support both sustainable and productive school environments for students and personnel. © 2010 John Wiley & Sons A/S.

Air change rates of motor vehicles and in-vehicle pollutant concentrations from secondhand smoke.

Science.gov (United States)

Ott, Wayne; Klepeis, Neil; Switzer, Paul

2008-05-01

The air change rates of motor vehicles are relevant to the sheltering effect from air pollutants entering from outside a vehicle and also to the interior concentrations from any sources inside its passenger compartment. We made more than 100 air change rate measurements on four motor vehicles under moving and stationary conditions; we also measured the carbon monoxide (CO) and fine particle (PM(2.5)) decay rates from 14 cigarettes smoked inside the vehicle. With the vehicle stationary and the fan off, the ventilation rate in air changes per hour (ACH) was less than 1 h(-1) with the windows closed and increased to 6.5 h(-1) with one window fully opened. The vehicle speed, window position, ventilation system, and air conditioner setting was found to affect the ACH. For closed windows and passive ventilation (fan off and no recirculation), the ACH was linearly related to the vehicle speed over the range from 15 to 72 mph (25 to 116 km h(-1)). With a vehicle moving, windows closed, and the ventilation system off (or the air conditioner set to AC Max), the ACH was less than 6.6 h(-1) for speeds ranging from 20 to 72 mph (32 to 116 km h(-1)). Opening a single window by 3'' (7.6 cm) increased the ACH by 8-16 times. For the 14 cigarettes smoked in vehicles, the deposition rate k and the air change rate a were correlated, following the equation k=1.3a (R(2)=82%; n=14). With recirculation on (or AC Max) and closed windows, the interior PM(2.5) concentration exceeded 2000 microg m(-3) momentarily for all cigarettes tested, regardless of speed. The concentration time series measured inside the vehicle followed the mathematical solutions of the indoor mass balance model, and the 24-h average personal exposure to PM(2.5) could exceed 35 microg m(-3) for just two cigarettes smoked inside the vehicle.

Performance of personalized ventilation combined with chilled ceiling in an office room: inhaled air quality and contaminant distribution

DEFF Research Database (Denmark)

Lipczynska, Aleksandra; Kaczmarczyk, Jan; Melikov, Arsen Krikor

2014-01-01

people (exhaled air, bioeffluents) and building materials (wall painting). Personalized ventilation combined with chilled ceiling ensured highest air quality at the workstation under all conditions. Pollutant concentration in the occupied zone away from the workstations did not differ substantially...... between the tested systems. Chilled ceiling combined with personalized ventilation working as the only air supplying system may be optimal solution in many buildings.......In a simulated two persons’ office room inhaled air quality and contaminant distribution provided with personalized ventilation combined with chilled ceiling, mixing ventilation only, chilled ceiling with mixing ventilation and chilled ceiling with mixing and personalized ventilation was studied...

Energy and cost associated with ventilating office buildings in a tropical climate.

Science.gov (United States)

Rim, Donghyun; Schiavon, Stefano; Nazaroff, William W

2015-01-01

Providing sufficient amounts of outdoor air to occupants is a critical building function for supporting occupant health, well-being and productivity. In tropical climates, high ventilation rates require substantial amounts of energy to cool and dehumidify supply air. This study evaluates the energy consumption and associated cost for thermally conditioning outdoor air provided for building ventilation in tropical climates, considering Singapore as an example locale. We investigated the influence on energy consumption and cost of the following factors: outdoor air temperature and humidity, ventilation rate (L/s per person), indoor air temperature and humidity, air conditioning system coefficient of performance (COP), and cost of electricity. Results show that dehumidification of outdoor air accounts for more than 80% of the energy needed for building ventilation in Singapore's tropical climate. Improved system performance and/or a small increase in the indoor temperature set point would permit relatively large ventilation rates (such as 25 L/s per person) at modest or no cost increment. Overall, even in a thermally demanding tropical climate, the energy cost associated with increasing ventilation rate up to 25 L/s per person is less than 1% of the wages of an office worker in an advanced economy like Singapore's. This result implies that the benefits of increasing outdoor air ventilation rate up to 25 L/s per person--which is suggested to provide for productivity increases, lower sick building syndrome symptom prevalence, and reduced sick leave--can be much larger than the incremental cost of ventilation.

Effect of solar chimney inclination angle on space flow pattern and ventilation rate

Energy Technology Data Exchange (ETDEWEB)

Bassiouny, Ramadan; Korah, Nader S.A. [Department of Mechanical Power Engineering and Energy, Minia University, Minia 61111 (Egypt)

2009-02-15

The solar chimney is a simple and practical idea that is applied to enhance space natural ventilation. The chimney could be vertical or inclined. The chimney inclination angle is an important parameter that greatly affects space flow pattern and ventilation rate. In the present study, the effect of chimney inclination angle on air change per hour and indoor flow pattern was numerically and analytically investigated. A numerical simulation using Ansys, a FEM-based code, was used to predict flow pattern. Then the results were compared with published experimental measurements. A FORTRAN program was developed to iteratively solve the mathematical model that was obtained through an overall energy balance on the solar chimney. The analytical results showed that an optimum air flow rate value was achieved when the chimney inclination is between 45 and 70 for latitude of 28.4 . The numerically predicted flow pattern inside the space supports this finding. Moreover, in the present study a correlation to predict the air change per hour was developed. The correlation was tested within a solar intensity greater than or equal to 500 W/m{sup 2}, and chimney width from 0.1 m to 0.35 m for different inclination angles with acceptable values. (author)

Preliminary study of ammonia emissions from naturally ventilated fattening pig houses in the south-east China

Energy Technology Data Exchange (ETDEWEB)

Wang, K.; Ye, Z.; Li, H. [Zhejiang Univ., Hangzhou City (China). School of Biosystems Engineering and Food Science

2010-07-01

This paper reported on an experimental simulation in which ammonia emissions from naturally ventilated pig houses were monitored and the ventilation airflow rate was estimated. Two identical pig houses and the same number of pigs were used in the study. Natural ventilation was used in the experimental pig house while the reference pig house had mechanical ventilation. Both houses had the same air temperature and relative humidity. The ventilation airflow rate of the experimental pig house was estimated by calculating the ventilation airflow rate in the reference pig house. The ventilation airflow rate of the experimental pig house was also estimated based on heat pressure theory. The room air temperature and relative humidity were found to be related to inlet air temperature and relative humidity for both ventilation systems. After 19 days, the average air temperature in the room with mechanical ventilation was about 4.1 degrees C higher than inlet air temperature, but the relative humidity was lower by 7.1 per cent. In the room with natural ventilation, the average air temperature after 19 days was about 3.9 degrees C higher than inlet air temperature, but the relative humidity was lower by 4.3 per cent.

Nunavut housing ventilation research 2003-2005

Energy Technology Data Exchange (ETDEWEB)

Fugler, D.

2005-11-15

Inuit children in Alaska and Nunavut have high rates of severe lower respiratory tract infections, with hospitalization rates of 300 per year for each 1000 infants. The aim of this research report was to summarize the findings of a pilot project measuring the indoor air quality (IAQ) in 20 Cape Dorset houses as well as a study measuring the ventilation rates of 100 house from 4 communities in Nunavut. The 20 house pilot study included a respiratory questionnaire; a detailed home inspection and data collection; a blower door airtightness test; 7 day measurements of nitrogen dioxide (NO{sub 2}), nicotine, carbon dioxide (CO{sub 2}), relative humidity and temperature; a natural air change rate testing using Brookhaven tracer gas technology; and settled floor dust and bed dust collection followed by biological analysis. The 100 house study recorded 3 to 5 days of house temperatures, relative humidity and CO{sub 2}. The Brookhaven tracer gas technique was used to establish house air change rate. A questionnaire was used to assess ventilation devices. A medical questionnaire was administered and an evaluation of hospitalization data was carried out. Results indicated that a large number of Nunavut houses were not adequately ventilated. In the 20 house study, a third of the houses showed air change rates that would be considered low by any ventilation standards, and that were very low when considering the high occupancy of the houses. In the hundred house study, almost all houses indicated a mean CO{sub 2} level over 1000 ppm, and peaks exceeded 2000 ppm in approximately half the houses. The concentrations were far higher than those seen in southern Canadian homes. It was concluded that the development and promotion of energy-efficient ventilation devices could help to resolve ventilation deficiencies in Nunavut. 2 figs.

Observations on the release of air from the rear end of ventilated cavities

International Nuclear Information System (INIS)

Verron, J.; Michel, J.M.

1976-01-01

In ventilated cavity flows, produced by air injection at the base of bi or tri-dimensional foils, the relation between the air flow rate and the relative cavity underpressure depends particularly on the way in which the air is released from the rear end of the cavity. The experiments show flow configurations of various kinds, revealing the influence of many parameters which interact to determine the closure region of the cavity. Examples are given in the cases of pulsating and non-pulsating cavities. The hydrodynamical tunnel is also briefly described with emphasis on the special units which allow to inject a large amount of air into the water and to produce large cavities without modifying the other characteristics: velocity, ambient pressure and air content in water [fr

Indoor radon concentration and its possible dependence on ventilation rate and flooring type

International Nuclear Information System (INIS)

Ashok, G. V.; Nagaiah, N.; Shiva Prasad, N. G.

2012-01-01

The results of radon concentration measurements carried out in dwellings with natural ventilation for 1 y in Bangalore are reported. Measurements, covering three sessions of the day (morning, afternoon, night) were performed two times in a month for 1 y at a fixed place of each dwelling at a height of 1 m above the ground surface in selected dwellings. The low-level radon detection system (LLRDS), an active method, was used for the estimation of radon concentration. The measurements were aimed to understand the diurnal variation and the effect of ventilation rate and flooring type on indoor radon concentration. The geometric mean (±geometric standard deviation) of indoor radon concentration from about 500 measurements carried out in 20 dwellings is found to be 25.4 ±1.54 Bq m -3 . The morning, afternoon and night averages were found to be 42.6 ±2.05, 15.3 ±2.18 and 28.5 ±2.2 Bq m -3 , respectively. The approximate natural ventilation rates of the dwellings were calculated using the PHPAIDA-the on-line natural ventilation, mixed mode and air infiltration rate calculation algorithm and their effects on indoor radon concentrations were studied. The inhalation dose and the lung cancer risk due to indoor radon exposure were found to be 0.66 mSv y -1 and 11.9 per 10 6 persons, respectively. The gamma exposure rate was also measured in all the dwellings and its correlation with the inhalation dose rate was studied. (authors)

Business approach to mine air quality and ventilation

Energy Technology Data Exchange (ETDEWEB)

Byrne, M.J. [Newmont Mining Corp., Greenwood Village, CO (United States)

2009-07-01

A business approach to air quality and ventilation in mines was discussed in this presentation. Issues that were addressed included leadership approaches in bridging the gap between the visible culture of policies and procedures with invisible cultures such as norms, assumptions and beliefs. An overview of occupational safety was also presented in terms of measuring diesel particulate matter (DPM) and key DPM activities such as ventilation modeling; remote control of ventilation circuits; real-time diagnostics of engine performance through electronic control modules; personnel and equipment tracking systems; remote carbon monoxide and carbon dioxide monitoring; and semi-quantitative real-time DPM monitoring. Resources such as ventilation engineers and other professionals also contribute to key DPM activities as do experience and good practice sharing between sites. The purpose of the presentation was to determine if 160 {mu}g/m{sup 3} is an achievable number for exposure to DPM and the standard by which mines should operate globally. figs.

A simulation Model of the Reactor Hall Ventilation and air Conditioning Systems of ETRR-2

International Nuclear Information System (INIS)

Abd El-Rahman, M.F.

2004-01-01

Although the conceptual design for any system differs from one designer to another. each of them aims to achieve the function of the system required. the ventilation and air conditioning system of reactors hall is one of those systems that really differs but always dose its function for which it is designed. thus, ventilation and air conditioning in some reactor hall constitute only one system whereas in some other ones, they are separate systems. the Egypt Research Reactor-2 (ETRR-2)represents the second type. most studies conducted on ventilation and air conditioning simulation models either in traditional building or for research rectors show that those models were not designed similarly to the model of the hall of ETRR-2 in which ventilation and air conditioning constitute two separate systems.besides, those studies experimented on ventilation and air conditioning simulation models of reactor building predict the temperature and humidity inside these buildings at certain outside condition and it is difficult to predict when the outside conditions are changed . also those studies do not discuss the influences of reactor power changes. therefore, the present work deals with a computational study backed by infield experimental measurements of the performance of the ventilation and air conditioning systems of reactor hall during normal operation at different outside conditions as well as at different levels of reactor power

Applied patent RFID systems for building reacting HEPA air ventilation system in hospital operation rooms.

Science.gov (United States)

Lin, Jesun; Pai, Jar-Yuan; Chen, Chih-Cheng

2012-12-01

RFID technology, an automatic identification and data capture technology to provide identification, tracing, security and so on, was widely applied to healthcare industry in these years. Employing HEPA ventilation system in hospital is a way to ensure healthful indoor air quality to protect patients and healthcare workers against hospital-acquired infections. However, the system consumes lots of electricity which cost a lot. This study aims to apply the RFID technology to offer a unique medical staff and patient identification, and reacting HEPA air ventilation system in order to reduce the cost, save energy and prevent the prevalence of hospital-acquired infection. The system, reacting HEPA air ventilation system, contains RFID tags (for medical staffs and patients), sensor, and reacting system which receives the information regarding the number of medical staff and the status of the surgery, and controls the air volume of the HEPA air ventilation system accordingly. A pilot program was carried out in a unit of operation rooms of a medical center with 1,500 beds located in central Taiwan from Jan to Aug 2010. The results found the air ventilation system was able to function much more efficiently with less energy consumed. Furthermore, the indoor air quality could still keep qualified and hospital-acquired infection or other occupational diseases could be prevented.

Human Response to Ductless Personalized Ventilation with Local Air Cleaning: Air Quality and Prevalence of SBS Symptoms

DEFF Research Database (Denmark)

Dalewski, Mariusz; Bivolarova, Maria; Fillon, Maelys

2013-01-01

The impact of local air cleaning and cooling of the head region by ductless personalized ventilation (DPV) on perceived air quality (PAQ) and Sick Building Syndrome (SBS) symptoms was studied. Thirty subjects participated in experiments performed in a test room with displacement ventilation (DV...... with air filter and 29 °C with DPV without filter. During the experiments the subjects simulated office work and answered on computerized questionnaires. At warm environment PAQ and air freshness significantly improved when DPV was used. Eye dryness increased significantly with time but was not influenced...... by air temperature and filtering. At 29 °C the facially applied air movement from DPV increased the eye dryness. The SBS symptoms increased with time and were higher (not significantly) at the warm conditions. Air movement did not have profound impact on the SBS symptoms, while filtering had only at 23...

Experimental study of perforated suspended ceilings as diffuse ventilation air inlets

DEFF Research Database (Denmark)

Hviid, Christian Anker; Svendsen, Svend

2013-01-01

An experimental study is reported in this paper for a diffuse ceiling ventilation concept. The analyses were carried out with two different porous surfaces mounted in a suspended ceiling: perforated tiles of aluminium and of gypsum. Ventilation air was supplied above the suspended ceiling effecti...... surface which increases the potential and applicability of the concept. Risk of thermal discomfort was not disclosed but the study did show evidence of large fluctuating air movements which could stem from transient behaviour creating sensations of draught to the occupants....

Estimation of Uncertainty in Tracer Gas Measurement of Air Change Rates

Directory of Open Access Journals (Sweden)

Atsushi Iizuka

2010-12-01

Full Text Available Simple and economical measurement of air change rates can be achieved with a passive-type tracer gas doser and sampler. However, this is made more complex by the fact many buildings are not a single fully mixed zone. This means many measurements are required to obtain information on ventilation conditions. In this study, we evaluated the uncertainty of tracer gas measurement of air change rate in n completely mixed zones. A single measurement with one tracer gas could be used to simply estimate the air change rate when n = 2. Accurate air change rates could not be obtained for n ≥ 2 due to a lack of information. However, the proposed method can be used to estimate an air change rate with an accuracy of

A preliminary study on the association between ventilation rates in classrooms and student performance.

Science.gov (United States)

Shaughnessy, R J; Haverinen-Shaughnessy, U; Nevalainen, A; Moschandreas, D

2006-12-01

Poor conditions leading to substandard indoor air quality (IAQ) in classrooms have been frequently cited in the literature over the past two decades. However, there is limited data linking poor IAQ in the classrooms to student performance. Whereas, it is assumed that poor IAQ results in reduced attendance and learning potential, and subsequent poor student performance, validating this hypothesis presents a challenge in today's school environment. This study explores the association between student performance on standardized aptitude tests that are administered to students on a yearly basis, to classroom carbon dioxide (CO2) concentrations, which provide a surrogate of ventilation being provided to each room. Data on classroom CO2 concentrations (over a 4-5 h time span within a typical school day) were recorded in fifth grade classrooms in 54 elementary schools within a school district in the USA. Results from this preliminary study yield a significant (P classroom-level ventilation rate and test results in math. They also indicate that non-linear effects may need to be considered for better representation of the association. A larger sample size is required in order to draw more definitive conclusions. Practical Implications Future studies could focus on (1) gathering more evidence on the possible association between classroom ventilation rates and students' academic performance; (2) the linear/non-linear nature of the association; and (3) whether it is possible to detect 'no observed adverse effect level' for adequate ventilation with respect to academic performance in schools. All of this information could be used to improve guidance and take regulatory actions to ensure adequate ventilation in schools. The high prevalence of low ventilation rates, combined with the growing evidence of the positive impact that sufficient ventilation has on human performance, suggests an opportunity for improving design and management of school facilities.

Pretest Predictions for Ventilation Tests

International Nuclear Information System (INIS)

Y. Sun; H. Yang; H.N. Kalia

2007-01-01

The objective of this calculation is to predict the temperatures of the ventilating air, waste package surface, concrete pipe walls, and insulation that will be developed during the ventilation tests involving various test conditions. The results will be used as input to the following three areas: (1) Decisions regarding testing set-up and performance. (2) Assessing how best to scale the test phenomena measured. (3) Validating numerical approach for modeling continuous ventilation. The scope of the calculation is to identify the physical mechanisms and parameters related to thermal response in the ventilation tests, and develop and describe numerical methods that can be used to calculate the effects of continuous ventilation. Sensitivity studies to assess the impact of variation of linear power densities (linear heat loads) and ventilation air flow rates are included. The calculation is limited to thermal effect only

Human response to ductless personalized ventilation coupled with displacement ventilation

DEFF Research Database (Denmark)

Dalewski, Mariusz; Veselý, Michal; Melikov, Arsen K.

2012-01-01

A human subject experiment was carried out to investigate the extent to which ductless personalized ventilation (DPV) in conjunction with displacement ventilation can improve perceived air quality (PAQ) and thermal comfort at elevated room air temperature in comparison with displacement ventilation...... alone. The experimental conditions comprised displacement ventilation alone (room air temperature of 23 °C, 26 °C, 29 °C) and DPV with displacement ventilation (26 °C, 29 °C), both operating at supply air temperatures 3, 5 or 6K lower than room air temperature, as well as mixing ventilation (23 °C, 3 K......). During one hour exposure participants answered questionnaires regarding PAQ and thermal comfort. PAQ was significantly better with DPV than without DPV at the same background conditions. Thermal comfort improved when DPV was used. Combining DPV with displacement ventilation showed the potential...

Experiments to Evaluate and Implement Passive Tracer Gas Methods to Measure Ventilation Rates in Homes

Energy Technology Data Exchange (ETDEWEB)

Lunden, Melissa [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Faulkner, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Heredia, Elizabeth [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Cohn, Sebastian [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Dickerhoff, Darryl [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Noris, Federico [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Logue, Jennifer [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Hotchi, Toshifumi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Singer, Brett [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sherman, Max H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2012-10-01

This report documents experiments performed in three homes to assess the methodology used to determine air exchange rates using passive tracer techniques. The experiments used four different tracer gases emitted simultaneously but implemented with different spatial coverage in the home. Two different tracer gas sampling methods were used. The results characterize the factors of the execution and analysis of the passive tracer technique that affect the uncertainty in the calculated air exchange rates. These factors include uncertainties in tracer gas emission rates, differences in measured concentrations for different tracer gases, temporal and spatial variability of the concentrations, the comparison between different gas sampling methods, and the effect of different ventilation conditions.

The Histoty of Ventilation and Air Conditioning is CERN Up to Date with the latest Technological Developments?

CERN Document Server

Kühnl-Kinel, J

2000-01-01

The invention of ventilation cannot be ascribed to a certain date. It started with simple aeration when man brought fire into his abode and continued through different stages including air cooling using ice to finally arrive at the time when ventilation and air conditioning has become an essential part of our life and plays an important role in human evolution. This paper presents the history of ventilation and air conditioning, explains the key constraints over the centuries, and shows its influence on everyday life. Some examples of previous air-conditioning plants are described and different approaches to the way of calculation of ventilation systems discussed. It gives an overview of the Heating, Ventilation and Air Conditioning (HVAC) installations at CERN and points out their particularities. It also compares them with the latest technological developments in the field as well as showing the new trends that are being applied at CERN.

Demand control on room level of the supply air temperature in an air heating and ventilation system

DEFF Research Database (Denmark)

Polak, Joanna; Afshari, Alireza; Bergsøe, Niels Christian

2017-01-01

air heating and ventilation system in a high performance single family house using BSim simulation software. The provision of the desired thermal conditions in different rooms was examined. Results show that the new control strategy can facilitate maintaining of desired temperatures in various rooms......The aim of this study was to investigate a new strategy for control of supply air temperature in an integrated air heating and ventilation system. The new strategy enables demand control of supply air temperature in individual rooms. The study is based on detailed dynamic simulations of a combined....... Moreover, this control strategy enables controlled temperature differentiation between rooms within the house and therefore provides flexibility and better balance in heat delivery. Consequently, the thermal conditions in the building can be improved....

Respiratory symptoms, perceived air quality and physiological signs in elementary school pupils in relation to displacement and mixing ventilation system: an intervention study.

Science.gov (United States)

Norbäck, D; Wieslander, G; Zhang, X; Zhao, Z

2011-10-01

Schools may be poorly ventilated and may contain furry pet allergens, particles and microorganisms. We studied health effects when changing from mixing ceiling ventilation to two types of displacement ventilation, front ventilation system (FVS) and floor master system (FMS). The study included pupils in three elementary school classes (N = 61), all with floor heating. One class received blinded interventions; the two others were unchanged (controls). Ventilation flow and supply air temperature was kept constant. The medical investigation included tear film stability (BUT), nasal patency and a questionnaire containing rating scales. When changing from mixing ventilation to FVS, the pupils (N = 26) perceived better air quality (P = 0.006) and less dyspnoea (P = 0.007) as compared to controls (N = 35), and BUT was improved (P = 0.03). At desk level, mean CO(2) was reduced from 867 to 655 ppm. Formaldehyde and viable bacteria were numerically lower, while total bacteria and molds were higher with displacement ventilation. There was no difference in symptoms or signs when changing from FVS to FMS. Cat (Der p1), dog (Can f1) and horse allergen (Equ cx) were common in air at all conditions. In conclusion, displacement ventilation may have certain positive health effects among pupils, as compared to conventional mixing ceiling systems. Displacement ventilation may be a suitable ventilation principle for achieving good indoor environment in classrooms. The type of supply air diffuser does not seem to be of major importance. The combination of floor heating and displacement ventilation can be a useful way of avoiding the previously described problem of thermal discomfort. © 2011 John Wiley & Sons A/S.

The Effects of Ventilation in Homes on Health

DEFF Research Database (Denmark)

Wargocki, Pawel

2013-01-01

and many of them suffer from deficient experimental design, as well as a lack of proper characterization of actual exposures occurring indoors. Based on the available data, in the reviewed studies, it seems likely that health risks may occur when ventilation rates are below 0.4 air changes per hour...... with existing ventilation systems this positive effect was less evident, probably due to poor performance of the system (too low ventilation rates and/or poor maintenance). Studies are recommended in which exposures are much better characterized (by for example measuring the pollutants indicated by the WHO...... Guidelines for Indoor Air Quality and improving ventilation measurements). Exposures should also be controlled using different ventilation methods for comparison. Future studies should also advance the understanding of how ventilation systems should be operated to achieve optimal performance. These data...

Ventilation system type, classroom environmental quality and pupils' perceptions and symptoms

DEFF Research Database (Denmark)

Gao, Jie; Wargocki, Pawel; Wang, Yi

2014-01-01

The present study investigated indoor climate and window opening behaviour by pupils, as well as their perceptions and symptoms in classrooms with different types of ventilation systems. Four classrooms were selected in the same school in suburban Denmark. Classroom ventilation was achieved either......-heating and heating seasons; CO2 concentration was used to estimate average classroom ventilation rates. At the end of each measuring period, the pupils were asked to report their perceptions of the indoor environment and their acute health-related symptoms. The classroom in which ventilation was achieved by manually...... operable windows had the highest air temperatures and CO2 concentrations during both non-heating and heating season; the estimated average air-change rate was lowest in this classroom. The classroom with mechanical ventilation had the highest estimated average air-change rate. Windows were frequently...

RedVent. Turned off ventilation at night in schools - risks and opportunities; RedVent. Avstaengd ventilation paa natten i skolor - risker och moejligheter

Energy Technology Data Exchange (ETDEWEB)

Haegerhed Engman, Linda; Fyhr, Kristina; Langer, Sarka; Ruud, Svein; Ylmen, Peter

2011-07-01

Reduced ventilation rates or shutdown ventilation during nights is often being used in school buildings in order to save energy and can decrease the energy cost for heating and ventilation with at least 30 %. Swedish Building Regulations (BBR) allows reduced ventilation flow in non-residential buildings when no one is using the building but it must not give rise to adverse health effects or damage the building or its installations. Potential risks are mould- and moisture damages and indoor air quality problems. Another question is whether the shut down itself might lead to indoor air quality problems due to chemical reactions between outdoor air and indoor emissions built-up during the night. The study was divided into three steps; an interview with property managers and care-taker, calculations of energy saving potentials and a field study. Measurements were per-formed in one classroom for two weeks in April 2010. Different set-ups for ventilation flow during night time and air tightness of the building envelope were studied; ventilation shut down, intermittent ventilation (15 min every second hour) and continuous full speed ventilation during night. In the studied classroom, shutdown ventilation during nights did not significantly affect the indoor air quality in the classroom during the school day even though there were effects seen during the night. We found a somewhat higher moisture accumulation those nights when the ventilation was shut down and some fractions of particles during intermittent ventilation compared to continues full ventilation during night time. This specific school and classroom were well ventilated and there was no moisture supply from new building material or other types of moisture producing activities. Schools with lower day-time ventilation rates, moisture in building construction, IAQ- or dampness problems as well as buildings close to heavy traffic should analyse the conditions for the specific building before reducing ventilation to

Basement depressurization using dwelling mechanical exhaust ventilation system

International Nuclear Information System (INIS)

Collignan, B.; O'Kelly, P.; Pilch, E.

2004-01-01

The mechanical ventilation exhaust system is commonly used in France to generate air renewal into building and especially into dwelling. It consists of a permanent mechanical air extraction from technical rooms (kitchen, bathrooms and toilets) using a unique fan connected to exhaust ducts. Natural air inlets in living room and bed rooms ensure an air flow from living spaces towards technical rooms. To fight against radon into building, the most recognised efficient technique is the Soil Depressurization System (S.D.S.) consisting in depressurizing the house basement. The aim of this study is to test the ability of the dwelling mechanical ventilation system to depressurize the basement in conjunction with air renewal of a house. For that purpose, a S.D.S. has been installed in an experimental house at CSTB during its construction. At first, tests undertaken with a variable velocity fan connected to the S.D.S. have characterised the permeability of the basement. It is shown that basement can be depressurized adequately with a relatively low air flow rate. At a second stage, S.D.S. has been connected to the exhaust ventilation fan used for the mechanical ventilation of the house. Results obtained show the ability of such ventilation system to generate sufficient depressurization in the basement and to ensure simultaneously adequate air change rate in the dwelling. (author)

Exposure to aerosol and gaseous pollutants in a room ventilated with mixing air distribution

DEFF Research Database (Denmark)

Bivolarova, Mariya Petrova; Ondráček, Jakub; Ždímal, Vladimír

2016-01-01

The present study investigates the aerosol and gas dispersal in a mechanically ventilated room and the personal exposure to these contaminants. The study was performed in a full-scale climate chamber. The room was air conditioned via mixing total volume ventilation system. The room occupancy was ...... of the thermal manikin were measured. The results showed higher exposure to the contaminants measured at the breathing zone than at the ambient air. The behaviour of the tracer gas and the aerosols was similar.......The present study investigates the aerosol and gas dispersal in a mechanically ventilated room and the personal exposure to these contaminants. The study was performed in a full-scale climate chamber. The room was air conditioned via mixing total volume ventilation system. The room occupancy...... was simulated by a sitting dressed thermal manikin with realistic body shape. During the experiments monodisperse aerosols of three sizes and nitrous oxide tracer gas were generated simultaneously from one location in the room. The aerosol and gas concentrations in the bulk room air and in the breathing zone...

Use of perforated acoustic panels as supply air diffusers in diffuse ceiling ventilation systems

DEFF Research Database (Denmark)

Iqbal, Ahsan; Kazemi, Seyed Hossein; Ardkapan, Siamak Rahimi

Ventilation is needed for diluting and removing the contaminants, odour and excess heat from the building interior. It is important that the inhabitants perceive the ventilated spaces as comfortable. Therefore, the supply air should reach all parts of the occupied zones. Troldtekt has been...... manufacturing perforated acoustic panels for the last 13 years. The panels can be used not only in applications related to acoustics but also as low pressure drop supply air diffusers, particularly in diffuse ceiling ventilation systems. The present study verifies on a theoretically level the performance...

Energy saving potential of natural ventilation in China: The impact of ambient air pollution

International Nuclear Information System (INIS)

Tong, Zheming; Chen, Yujiao; Malkawi, Ali; Liu, Zhu; Freeman, Richard B.

2016-01-01

Highlights: • Natural ventilation potential is affected largely by ambient air pollution in China. • NV hours of 76 Chinese cities based on weather and ambient air quality are estimated. • Cooling energy savings and carbon reductions of 35 major Chinese cities are estimated. • 8–78% of the cooling energy usage can be potentially reduced by NV. • Our findings provide guidelines to improve energy policies in China. - Abstract: Natural ventilation (NV) is a key sustainable solution for reducing the energy use in buildings, improving thermal comfort, and maintaining a healthy indoor environment. However, the energy savings and environmental benefits are affected greatly by ambient air pollution in China. Here we estimate the NV potential of all major Chinese cities based on weather, ambient air quality, building configuration, and newly constructed square footage of office buildings in the year of 2015. In general, little NV potential is observed in northern China during the winter and southern China during the summer. Kunming located in the Southwest China is the most weather-favorable city for natural ventilation, and reveals almost no loss due to air pollution. Building Energy Simulation (BES) is conducted to estimate the energy savings of natural ventilation in which ambient air pollution and total square footage at each city must be taken into account. Beijing, the capital city, displays limited per-square-meter saving potential due to the unfavorable weather and air quality for natural ventilation, but its largest total square footage of office buildings makes it become the city with the greatest energy saving opportunity in China. Our analysis shows that the aggregated energy savings potential of office buildings at 35 major Chinese cities is 112 GWh in 2015, even after allowing for a 43 GWh loss due to China’s serious air pollution issue especially in North China. 8–78% of the cooling energy consumption can be potentially reduced by natural

Optimization of Occupancy Based Demand Controlled Ventilation in Residences

DEFF Research Database (Denmark)

Mortensen, Dorthe Kragsig; Walker, Iain; Sherman, Max

2011-01-01

Although it has been used for many years in commercial buildings, the application of demand controlled ventilation in residences is limited. In this study we used occupant exposure to pollutants integrated over time (referred to as "dose") as the metric to evaluate the effectiveness and air quality...... implications of demand controlled ventilation in residences. We looked at air quality for two situations. The first is that typically used in ventilation standards: the exposure over a long term. The second is to look at peak exposures that are associated with time variations in ventilation rates and pollutant...... when occupied. We used analytical solutions to the continuity equation to determine the ventilation effectiveness and the long-term chronic dose and peak acute exposure for a representative range of occupancy periods, pollutant generation rates and airflow rates. The results of the study showed that we...

Review and Extension of CO2-Based Methods to Determine Ventilation Rates with Application to School Classrooms

Directory of Open Access Journals (Sweden)

Stuart Batterman

2017-02-01

Full Text Available The ventilation rate (VR is a key parameter affecting indoor environmental quality (IEQ and the energy consumption of buildings. This paper reviews the use of CO2 as a “natural” tracer gas for estimating VRs, focusing on applications in school classrooms. It provides details and guidance for the steady-state, build-up, decay and transient mass balance methods. An extension to the build-up method and an analysis of the post-exercise recovery period that can increase CO2 generation rates are presented. Measurements in four mechanically-ventilated school buildings demonstrate the methods and highlight issues affecting their applicability. VRs during the school day fell below recommended minimum levels, and VRs during evening and early morning were on the order of 0.1 h−1, reflecting shutdown of the ventilation systems. The transient mass balance method was the most flexible and advantageous method given the low air change rates and dynamic occupancy patterns observed in the classrooms. While the extension to the build-up method improved stability and consistency, the accuracy of this and the steady-state method may be limited. Decay-based methods did not reflect the VR during the school day due to heating, ventilation and air conditioning (HVAC system shutdown. Since the number of occupants in classrooms changes over the day, the VR expressed on a per person basis (e.g., L·s−1·person−1 depends on the occupancy metric. If occupancy measurements can be obtained, then the transient mass balance method likely will provide the most consistent and accurate results among the CO2-based methods. Improved VR measurements can benefit many applications, including research examining the linkage between ventilation and health.

Inadequate ventilation for nosocomial tuberculosis prevention in public hospitals in Central Thailand.

Science.gov (United States)

Jiamjarasrangsi, W; Bualert, S; Chongthaleong, A; Chaindamporn, A; Udomsantisuk, N; Euasamarnjit, W

2009-04-01

Forty-two community and general hospitals in central Thailand. To examine the adequacy of indoor ventilation for nosocomial tuberculosis (TB) prevention in public hospitals in central Thailand. A cross-sectional survey was conducted among 323 patient care and ancillary areas in the target hospitals. Data on indoor ventilation rate were collected by the tracer gas method and reported as air changes per hour (ACH). The adequacy of the measured ventilation rates were then determined by comparison with the international recommended standard values. Indoor ventilation rates were inadequate in almost half of the studied areas (144/323, 44.6%). The inadequacy was particularly serious in the emergency rooms (ERs) and radiological areas, where 73.8% (31/42 each) of the rooms had ACH below the recommended standards. Detailed analysis showed that most of the rooms with natural ventilation had air exchange rates that exceeded the recommended standards, while the opposite was the case for rooms with air-conditioning, particularly the window or wall-mount type. Indoor ventilation in high-risk nosocomial TB areas in public hospitals in Thailand was inadequate due to the installation of air-conditioning systems in modern buildings.

The IVAIRE project--a randomized controlled study of the impact of ventilation on indoor air quality and the respiratory symptoms of asthmatic children in single family homes.

Science.gov (United States)

Lajoie, P; Aubin, D; Gingras, V; Daigneault, P; Ducharme, F; Gauvin, D; Fugler, D; Leclerc, J-M; Won, D; Courteau, M; Gingras, S; Héroux, M-È; Yang, W; Schleibinger, H

2015-12-01

A randomized controlled trial was carried out to measure the impact of an intervention on ventilation, indoor air contaminants, and asthma symptoms of children. Eighty-three asthmatic children living in low-ventilated homes were followed over 2 years. Several environmental parameters were measured during the summer, fall, and winter. The children were randomized after Year 1 (43 Intervention; 40 Control). The intervention included the installation of either a Heat Recovery Ventilator (HRV) or Energy Recovery Ventilator (ERV). During the fall and winter seasons, there was a significant increase in the mean ventilation rate in the homes of the intervention group. A statistically significant reduction in mean formaldehyde, airborne mold spores, toluene, styrene, limonene, and α-pinene concentrations was observed in the intervention group. There was no significant group difference in change in the number of days with symptoms per 14 days. However, there was a significant decrease in the proportion of children who experienced any wheezing (≥1 episode) and those with ≥4 episodes in the 12-month period in the intervention group. This study indicates that improved ventilation reduces air contaminants and may prevent wheezing. Due to lack of power, a bigger study is needed. Positive findings from this study include the fact that, upon recruitment, most of the single family homes with asthmatic children were already equipped with a mechanical ventilation system and had relatively good indoor air quality. However, the 8-h indoor guideline for formaldehyde (50 μg/m3) was frequently exceeded and the ventilation rates were low in most of the homes, even those with a ventilation system. Both ERVs and HRVs were equally effective at increasing air exchange rates above 0.30 ACH and at preventing formaldehyde concentrations from exceeding the 50 μg/m3 guideline during the fall and winter seasons. Furthermore, the ERVs were effective at preventing excessively low relative

Characteristics of rain penetration through a gravity ventilator used for natural ventilation.

Science.gov (United States)

Kim, Taehyeung; Lee, Dong Ho; Ahn, Kwangseog; Ha, Hyunchul; Park, Heechang; Piao, Cheng Xu; Li, Xiaoyu; Seo, Jeoungyoon

2008-01-01

Gravity ventilators rely simply on air buoyancy to extract air and are widely used to exhaust air contaminants and heat from workplaces using minimal energy. They are designed to maximize the exhaust flow rate, but the rain penetration sometimes causes malfunctioning. In this study, the characteristics of rain penetration through a ventilator were examined as a preliminary study to develop a ventilator with the maximum exhaust capacity while minimizing rain penetration. A model ventilator was built and exposed to artificial rain and wind. The paths, intensities and amounts of penetration through the ventilator were observed and measured in qualitative and quantitative fashions. In the first phase, the pathways and intensities of rain penetration were visually observed. In the second phase, the amounts of rain penetration were quantitatively measured under the different configurations of ventilator components that were installed based on the information obtained in the first-phase experiment. The effects of wind speed, grill direction, rain drainage width, outer wall height, neck height and leaning angle of the outer wall from the vertical position were analyzed. Wind speed significantly affected rain penetration. Under the low crosswind conditions, the rain penetration intensities were under the limit of detection. Under the high crosswind conditions, grill direction and neck height were the most significant factors in reducing rain penetration. The installation of rain drainage was also important in reducing rain penetration. The experimental results suggest that, with proper configurations of its components, a gravity ventilator can be used for natural ventilation without significant rain penetration problems.

Modulating ventilation - low cost VAV for office buildings. [Variable Air Volume]; Modulerende ventilation - low cost VAV til kontor-bygninger. Slutrapport

Energy Technology Data Exchange (ETDEWEB)

Hoej Christensen, A.; Olsen, Hans; Drivsholm, C.

2012-02-15

The report describes a concept for renovating older existing Constant Air Volume (CAV) ventilation systems to modulating low-cost Variable Air Volume (VAV) systems. The concept is based on the total ventilated area being divided into appropriate indoor climate zones, which can cover from one to several offices with similar climate needs. For this initial climate assessment two relatively ''simple'' tools were developed that can estimate the temperature level in one room from the ventilation airflow, heat loads, etc.: - BSimFast (24-hour mean temperature calculation according to SBI-196, 2000); - BSimLight (Temperature simulation based on Danvak Textbook of Heat and Climate Technology). The concept of 'one room' can also be extended to 'one zone' with appropriate assumptions. However, only one mean room temperature is calculated. The different climate zones were equipped with Halton HFB control unit at the air supply and exhaust side. The project the following feedback options were used: - HFB unit's damper opening degree (0 to 90 degrees); - HFB unit's current flow; - HFB unit's exhaust temperature; and feedback from: - Frequency transformer (fan speed); - The central static duct pressure at the ventilation unit. In the project a control algorithm is developed that ensures a robust control of the entire ventilation system without adverse cyclic variations, based among other things on the exhaust temperature for each climate zone, and with the requirement that at least one throttle valve is always at least 80% open. It turned out that information on the current partial air volumes was necessary in addition to the individual throttle settings. Otherwise, a cyclic variations could not be controlled..Thus, it was the exhaust temperature from individual climate zones that defined the respective volumes of air. The concept was implemented on a complete CAV system and on part of a large CAV system, respectively. (LN)

Numerical Simulation of Air Temperature and Velocity in a Naturally Ventilated Office

Directory of Open Access Journals (Sweden)

S. Shodiya

2017-04-01

Full Text Available This paper presents a numerical simulation of air velocity and air temperature distribution in an office room of Computer Engineering Department of University of Maiduguri which is naturally ventilated. The office room under investigation with the dimension 5 m × 5 m × 4 m has a door in the East direction, and two windows, one in the East direction and the other in the South direction. For cost effectiveness, numerical solutions of steady-state airflow and heat transfer were done using a complete two-dimensional model. The results showed that the windows and the door could not undertake indoor heat load that can make the occupants to be thermally comfortable. In activity area where people sit and stand, the air velocity is moderate, this is about 0.98 m/s on the average. In addition, the temperature in this area is relatively high of about 302 K (29 °C on the average. Based on the American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE standard for comfort environment in summer (air temperature: 293 – 299 K (20 – 26 °C; air velocity: 0.5 – 0.8 m/s, the natural ventilation for the office room cannot give a thermal comfort for the inhabitant of the room. However, a window, if installed opposite the door could improve the ventilation of the office.

Diffuse ceiling ventilation

DEFF Research Database (Denmark)

Zhang, Chen

Diffuse ceiling ventilation is an innovative ventilation concept where the suspended ceiling serves as air diffuser to supply fresh air into the room. Compared with conventional ventilation systems, diffuse ceiling ventilation can significantly reduce or even eliminate draught risk due to the low...

Reduced energy use for ventilation of buildings through selection of low-polluting building materials and furniture. Final Report; Reduceret energiforbrug til ventilation af bygninger hvori der systematisk er valgt lav-forurenende materialer og inventar. Slutrapport

Energy Technology Data Exchange (ETDEWEB)

2007-11-15

The main objective of the research project was to study the potential of reducing energy used for ventilating buildings by using low-polluting building materials and thereby ensuring that indoor air quality will not be compromised. To quantify this potential, the exposure-response relationships, i.e. the relationships between ventilation rate and the perceived indoor air quality (indoor air quality perceived by humans as opposed to indoor air quality evaluated by chemical measurements), were established for rooms furnished with different more or less polluting materials. Based on these results simulations of energy used for ventilation were carried out for selected building scenarios. The exposure-response relationships were established by summarizing existing data reported in the literature and by a series of new experiments. The data summarized by reviewing the literature included data for building materials and furnishing tested in a laboratory setting in small-scale ventilated glass chambers, and in full-scale in ventilated climate chambers, test rooms or normal offices. Relevant low-polluting building materials were selected based on the literature review and a series of new experiments performed in ventilated small-scale glass chambers. Then the final experiments in which the effects of using low-polluting materials on perceived air quality were carried out in ventilated small-scale glass chambers and in full-scale test rooms ventilated with different outdoor air supply rates. Simulations of energy used for ventilation were carried out using BSim software. During simulations the ventilation rate was varied to obtain different levels of air quality when low-polluting building materials had been used, and it was examined how these changes influence the energy use. The results show that the exposure-response relationships vary between different building materials and thus the ventilation requirement to achieve a certain level of perceived indoor air quality vary

Wearable Personal Exhaust Ventilation, WPEV: Improved Indoor Air Quality and Reduced Exposure to Air Exhaled from a Sick Doctor

DEFF Research Database (Denmark)

Bolashikov, Zhecho D.; Barova, Maria; Melikov, Arsen K.

2015-01-01

pause) and a tidal flow rate of 6 L/min. A second thermal manikin and heated dummy were used to resemble lying patients. Exhaled air by the doctor was mixed with tracer gas to mimic pathogens. The wearable personal exhaust unit was positioned frontally by the mouth of the doctor at three distances: 0.......02, 0.04, and 0.06 m. It was operated at 0.25 or 0.50 L/s under mixing background ventilation at three air changes per hour. The effect of the wearable exhaust unit geometry by modifying the exhaust surface, as well as the posture of the doctor, standing or seated, was also studied. The use...... of the wearable personal exhaust resulted in cleaner air in the room compared to mixing alone at 12 air changes per hour, reducing the exposure of the two patients. The nozzle geometry and posture of the doctor affected the indoor exposure to exhaled air. The high potential to capture exhaled air makes the device...

The Histoty of Ventilation and Air Conditioning: is CERN Up to Date with the latest Technological Developments?

OpenAIRE

Kühnl-Kinel, J

2000-01-01

The invention of ventilation cannot be ascribed to a certain date. It started with simple aeration when man brought fire into his abode and continued through different stages including air cooling using ice to finally arrive at the time when ventilation and air conditioning has become an essential part of our life and plays an important role in human evolution. This paper presents the history of ventilation and air conditioning, explains the key constraints over the centuries, and shows its i...

The effect of a personalized ventilation system on perceived air quality and SBS symptoms

DEFF Research Database (Denmark)

Kaczmarczyk, Jan; Zeng, Q.; Melikov, Arsen Krikor

2002-01-01

Perceived air quality, SBS symptoms and performance were studied with 30 human subjects. Experiments were performed in an office set-up with six workplaces, each equipped with a Personalized Ventilation System (PVS). Each PVS allowed the amount of supply air and its direction to be controlled...... condition in regard to perceived air quality, perception of freshness and intensity of SBS symptoms was when PVS supplied outdoor air at 20 deg.C. Perceived air quality in this case was significantly better (p....... Subjects participated in four experiments: (1) PVS supplying outdoor air at 20 deg.C; (2) PVS supplying outdoor air at 23 deg.C; (3) PVS supplying recirculated room air; and (4) mixing ventilation. Room temperature was kept constant at 23 deg.C and relative humidity at 30%. Results showed that the best...

Modeling and Control of Livestock Ventilation Systems and Indoor Environments

DEFF Research Database (Denmark)

Wu, Zhuang; Heiselberg, Per; Stoustrup, Jakob

2005-01-01

The hybrid ventilation systems have been widely used for livestock barns to provide optimum indoor climate by controlling the ventilation rate and air flow distribution within the ventilated building structure. The purpose of this paper is to develop models for livestock ventilation systems and i...

Optimization of Ventilation Energy Demands and Indoor Air Quality in the ZEBRAlliance Homes

Energy Technology Data Exchange (ETDEWEB)

Hun, D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jackson, M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shrestha, S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2013-09-01

High-performance homes require that ventilation energy demands and indoor air quality (IAQ) be simultaneously optimized. In this project, Oak Ridge National Laboratory researchers attempted to bridge these two areas by conducting tests in research houses located in Oak Ridge, TN, that were less than 2 years old, energy-efficient (i.e., expected to consume 50% less energy than a house built per the 2006 IRC), tightly-built, unoccupied, and unfurnished. The team identified air pollutants of concern in the test homes that could generally serve as indicators of IAQ, and conduced field experiments and computer simulations to determine the effectiveness and energy required by various techniques that lessened the concentration of these contaminants. Formaldehyde was selected as the main pollutant of concern from initial air sampling surveys. Field data indicate that concentrations were higher during the summer primarily because emissions from sources rise with increases in temperature. Furthermore, supply ventilation and gas-phase filtration were effective means to reduce formaldehyde concentrations; however, exhaust ventilation had minimal influence on this pollutant. Results from simulations suggest that formaldehyde concentrations obtained while ventilating per ASHRAE 62.2-2010 could be decreased by about 20% from May through September through three strategies: 1) increasing ASHRAE supply ventilation by a factor of two, 2) reducing the thermostat setpoint from 76 to 74°F, or 3) running a gas-phase filtration system while decreasing supply ventilation per ASHRAE by half. In the mixed-humid climate of Oak Ridge, these strategies caused minimal to modest increases in electricity cost of ~$5 to ~$15/month depending on outdoor conditions.

Measurement and Numerical Simulation of Air Velocity in a Tunnel-Ventilated Broiler House

Directory of Open Access Journals (Sweden)

Eliseo Bustamante

2015-02-01

Full Text Available A building needs to be designed for the whole period of its useful life according to its requirements. However, future climate predictions involve some uncertainty. Thus, several sustainable strategies of adaptation need to be incorporated after the initial design. In this sense, tunnel ventilation in broiler houses provides high air velocity values (2–3 m·s−1 at animal level to diminish their thermal stress and associated mortality. This ventilation system was experimentally incorporated into a Mediterranean climate. The aim was to resolve these thermal problems in hot seasons, as (traditional cross-mechanical ventilation does not provide enough air velocity values. Surprisingly, very little information on tunnel ventilation systems is available, especially in terms of air velocity. Using Computational Fluid Dynamics (CFD and a multi-sensor system, the average results are similar (at animal level: 1.59 ± 0.68 m·s−1 for CFD and 1.55 ± 0.66 m·s−1 for measurements. The ANOVA for validation concluded that the use of CFD or measurements is not significant (p-value = 0.1155. Nevertheless, some problems with air velocity distribution were found and need to be solved. To this end, CFD techniques can help by means of virtual designs and scenarios providing information for the whole indoor space.

Improving energy performance of school buildings while ensuring indoor air quality ventilation

Energy Technology Data Exchange (ETDEWEB)

Becker, Rachel; Goldberger, Itamar [Technion - Israel Institute of Technology, Haifa (Israel). Faculty of Civil and Environmental Engineering, Department of Structural Engineering and Construction Management; Paciuk, Monica [National Building Research Institute, Technion, Haifa (Israel)

2007-09-15

Energy conscious design of school buildings, as well as deemed-to-satisfy provisions in a Performance Based Energy Code, should address the problem known as the energy efficiency - thermal comfort - indoor air quality dilemma (EE-TC-IAQ Dilemma). In warm and moderate climates, the large internal heat sources usually found in school buildings prevent achieving thermal comfort without active cooling in summer, but are not sufficient to eliminate the need for heating in winter. Commonly used air-conditioners do not improve air quality, while natural ventilation induces uncontrolled energy losses. In this study, a step by step process was used for the development of deemed-to-satisfy design solutions, which cope with the EE-TC-IAQ Dilemma, for a performance based code. A distinction is made between improving building design variables and improving ventilation schemes. Results indicate that implementation of improved ventilation schemes in an otherwise well designed energy-conscious building result in savings of 28-30% and 17-18% for northern and southern classroom orientations, respectively. (author)

Human Response to Ductless Personalised Ventilation: Impact of Air Movement, Temperature and Cleanness on Eye Symptoms

DEFF Research Database (Denmark)

Dalewski, Mariusz; Fillon, Maelys; Bivolarova, Maria

2013-01-01

environment facially applied individually controlled air movement of room air, with or without local filtering, did not have significant impact on eye blink frequency and tear film quality. The local air movement and air cleaning resulted in increased eye blinking frequency and improvement of tear film......The performance of ductless personalized ventilation (DPV) in conjunction with displacement ventilation (DV) was studied in relation to peoples’ health, comfort and performance. This paper presents results on the impact of room air temperature, using of DPV and local air filtration on eye blink...

Solar Air Collectors for Space Heating and Ventilation Applications—Performance and Case Studies under Romanian Climatic Conditions

Directory of Open Access Journals (Sweden)

Sanda Budea

2014-06-01

Full Text Available Solar air collectors have various applications: on the one hand, they can be used for air heating in cold seasons; on the other hand they can be used in summer to evacuate the warm and polluted air from residential, offices, industrial, and commercial buildings. The paper presents experimental results of a solar collector air, under the climatic conditions of the Southeastern Europe. The relationships between the direct solar irradiation, the resulting heat flow, the air velocity at the outlet, the air flow rate, the nominal regime of the collector and the efficiency of conversion of solar energy into thermal energy are all highlighted. Thus, it was shown that after a maximum 50 min, solar air collectors, with baffles and double air passage can reach over 50% efficiency for solar irradiation of 900–1000 W/m2. The article also presents a mathematical model and the results of a computational program that allows sizing solar collectors for the transfer of air, with the purpose of improving the natural ventilation of buildings. The article is completed with case studies, sizing the area to be covered with solar collectors, to ensure ventilation of a house with two floors or for an office building. In addition, the ACH (air change per hour coefficient was calculated and compared.

Ventilation Systems Operating Experience Review for Fusion Applications

International Nuclear Information System (INIS)

Cadwallader, L.C.

1999-01-01

This report is a collection and review of system operation and failure experiences for air ventilation systems in nuclear facilities. These experiences are applicable for magnetic and inertial fusion facilities since air ventilation systems are support systems that can be considered generic to nuclear facilities. The report contains descriptions of ventilation system components, operating experiences with these systems, component failure rates, and component repair times. Since ventilation systems have a role in mitigating accident releases in nuclear facilities, these data are useful in safety analysis and risk assessment of public safety. An effort has also been given to identifying any safety issues with personnel operating or maintaining ventilation systems. Finally, the recommended failure data were compared to an independent data set to determine the accuracy of individual values. This comparison is useful for the International Energy Agency task on fusion component failure rate data collection

Ventilation models

Science.gov (United States)

Skaaret, Eimund

Calculation procedures, used in the design of ventilating systems, which are especially suited for displacement ventilation in addition to linking it to mixing ventilation, are addressed. The two zone flow model is considered and the steady state and transient solutions are addressed. Different methods of supplying air are discussed, and different types of air flow are considered: piston flow, plane flow and radial flow. An evaluation model for ventilation systems is presented.

A Chemical-Biological-Radio-Nuclear (CBRN) Filter can be Added to the Air-Outflow Port of a Ventilator to Protect a Home Ventilated Patient From Inhalation of Toxic Industrial Compounds.

Science.gov (United States)

Be'eri, Eliezer; Owen, Simon; Beeri, Maurit; Millis, Scott R; Eisenkraft, Arik

2018-02-21

Chemical-biological-radio-nuclear (CBRN) gas masks are the standard means for protecting the general population from inhalation of toxic industrial compounds (TICs), for example after industrial accidents or terrorist attacks. However, such gas masks would not protect patients on home mechanical ventilation, as ventilator airflow would bypass the CBRN filter. We therefore evaluated in vivo the safety of adding a standard-issue CBRN filter to the air-outflow port of a home ventilator, as a method for providing TIC protection to such patients. Eight adult patients were included in the study. All had been on stable, chronic ventilation via a tracheostomy for at least 3 months before the study. Each patient was ventilated for a period of 1 hour with a standard-issue CBRN filter canister attached to the air-outflow port of their ventilator. Physiological and airflow measurements were made before, during, and after using the filter, and the patients reported their subjective sensation of ventilation continuously during the trial. For all patients, and throughout the entire study, no deterioration in any of the measured physiological parameters and no changes in measured airflow parameters were detected. All patients felt no subjective difference in the sensation of ventilation with the CBRN filter canister in situ, as compared with ventilation without it. This was true even for those patients who were breathing spontaneously and thus activating the ventilator's trigger/sensitivity function. No technical malfunctions of the ventilators occurred after addition of the CBRN filter canister to the air-outflow ports of the ventilators. A CBRN filter canister can be added to the air-outflow port of chronically ventilated patients, without causing an objective or subjective deterioration in the quality of the patients' mechanical ventilation. (Disaster Med Public Health Preparedness. 2018;page 1 of 5).

Optimizing of Make Up Air Performance for Commercial Kitchen Ventilation Improvement

Directory of Open Access Journals (Sweden)

Manshoor B.

2014-07-01

Full Text Available A commercial kitchen is a complicated environment where multiple components of a ventilation system including kitchen hood, exhaust fan, air supply, and make up air systems work together but not always in unison. For the commercial kitchen environment, make up air systems used to control the kitchen space from unwanted odor and thermal confort. Make air systems for commercial kitchen already established. However, an optimization is important to determine the most suitable make air systems and at the same time can improve the thermal comfort in the working space. In this study, a simulation work was conducted to investigate a suitable supply air velocity to optimize the make up air for kitchen ventilation system. In order to achieve the objectives, ANSYS FLUENT software (CFD was used to carry out the simulation and analysis. 3D kitchen space with 10m x 8m x 3m with air supply velocity was set to 0 m/s, 0.14 m/s, 0.28 m/s and 0.42 m/s. From the simulation work, the velocity of air flow tested which is 0.28 m/s is enough to control the heat and give an enough comfort to the working space for the size of kitchen simulated. Well implementation of the make up air in the kitchen hood can improve an air quality in the commercial kitchen and also keep the kitchen space comfortable to the workers.

History of ventilation and of air conditioning in Dolni Rozinka uranium mines

International Nuclear Information System (INIS)

Voltr, S.

1987-01-01

At a time of the start of mining operations in the Dolni Rozinka uranium mine, ventilation had been provided using the underpressure technique with diagonal winding shafts. From 1967 the overpressure system had been used. The system is described in detail and its constraints are listed. In 1983, on the basis of an analysis and model tests, the ventilation system was replaced by a underpressure system which satisfied the current hygiene specifications, was costsaving and reliable. Since 1985, an air conditioning system has been in operation featuring mobile cooling units and a closed-circuit air conditioning water system that is separated from the mining water pumping system. In view of the favourable temperature factors of the deposit, the mobile air conditioning units are only installed in blind headings. When the through-flow wind stream is achieved, air conditioning is abandoned. (J.B.). 2 figs., 5 refs

Ventilation effectiveness : health benefits of heat recovery ventilators

Energy Technology Data Exchange (ETDEWEB)

Anon.

2010-08-15

Studies have shown that the installation of a heat recovery ventilator (HRV) in homes in northern Canada could improve indoor air quality and the respiratory health of inhabitants. Low ventilation rates are common in many homes in the North because the climate is severe, homes are smaller and lack basements, and occupancies are higher, leading to unhealthy indoor air quality. Northern communities also have a high rate of respiratory infections. HRVs recover much of the energy used to ventilate, which is desirable in cold regions with high heating costs. For the study, the test sample was divided into two types of houses, notably houses with active HRVs and those with control HRVs that were installed and operated but that did not function. The study results showed that HRVs provided increased ventilation. Complaints by residents about HRV noise, discomfort, or low humidity were common but equally spread between those with active and placebo HRVs. The study showed that the system design needs to be improved to better suit the needs of Inuit families. The nature of northern housing presents installation and maintenance challenges. It is hard to retrofit HRV ducting inside small, existing houses, and building supplies arrive infrequently, so detailed planning and careful take-offs of all supplies and materials must be done well in advance of construction. In addition, contractors are hard to locate and have variable expertise, and there is little technical follow-up. Robust technical support by local contractors and housing authorities is therefore important. 2 refs.

Comparison of ventilation measurement techniques in real conditions

International Nuclear Information System (INIS)

Jilek, K.; Tomasek, L.

2001-01-01

Ventilation and radon entry rate are the only two quantities that influence on indoor radon behaviour. In order to investigate the effect of ventilation and radon entry rate on indoor radon behaviour separately , the Institute was equipped with continuous monitor of carbon monoxide (CO). Carbon monoxide serves as a tracer gas for the determination of air exchange rate. The use of a continuous radon monitor and the continuous monitor of CO gas at the same time enables to measure the radon entry rate and the air exchange rate separately. In the lecture are summarized results of comparison of the following three basic methods performed in real living conditions: - constant decay method; - constant tracer method; and steady rate of tracer injection to determine the air exchange rate for 222 Rn and CO gas, which were used as tracer gases. (authors)

Nasal congestion in relation to low air exchange rate in schools. Evaluation by acoustic rhinometry.

Science.gov (United States)

Wålinder, R; Norbäck, D; Wieslander, G; Smedje, G; Erwall, C

1997-09-01

Upper airway symptoms are common, but there is little information available on clinical findings in relation to indoor air pollution. This pilot study was conducted to test whether increased levels of indoor air pollutants in schools may correlate to a swelling of the nasal mucosa. The assumption was made that the degree of swelling could be related to the degree of decongestive effect of xylometazoline, and measured by acoustic rhinometry. The study was performed among 15 subjects in a school with low air exchange rate (0.6 air changes/h) and 12 subjects in a school with high air exchange rate (5.2 air changes/h). Hygienic measurements were performed in both schools. Acoustic rhinometry was performed for each individual under standardized forms. Cross-sectional areas and volumes of the nasal cavity were measured before and after decongestion with xylometazoline hydrochloride. Absolute values of the minimal cross-sectional area were lower in the school with poor ventilation. The decongestive effect of xylometazoline was significantly higher in the school with low air exchange, when correction for the influence of age was made. A diminished decongestive effect was seen with increasing age. The exposure measurements showed that indoor concentrations of volatile organic compounds, bacteria and moulds were higher in the school with low ventilation. In conclusion, raised levels of indoor air pollutants due to inadequate ventilation in schools may affect the upper airways and cause a swelling of the nasal mucosa, and acoustic rhinometry could be a useful objective method to measure human nasal reactions to the indoor environment.

Ventilation and Air Quality in City Blocks Using Large-Eddy Simulation—Urban Planning Perspective

Directory of Open Access Journals (Sweden)

Mona Kurppa

2018-02-01

Full Text Available Buildings and vegetation alter the wind and pollutant transport in urban environments. This comparative study investigates the role of orientation and shape of perimeter blocks on the dispersion and ventilation of traffic-related air pollutants, and the street-level concentrations along a planned city boulevard. A large-eddy simulation (LES model PALM is employed over a highly detailed representation of the urban domain including street trees and forested areas. Air pollutants are represented by massless and passive particles (non-reactive gases, which are released with traffic-related emission rates. High-resolution simulations for four different city-block-structures are conducted over a 8.2 km 2 domain under two contrasting inflow conditions with neutral and stable atmospheric stratification corresponding the general and wintry meteorological conditions. Variation in building height together with multiple cross streets along the boulevard improves ventilation, resulting in 7–9% lower mean concentrations at pedestrian level. The impact of smaller scale variability in building shape was negligible. Street trees further complicate the flow and dispersion. Notwithstanding the surface roughness, atmospheric stability controls the concentration levels with higher values under stably stratified inflow. Little traffic emissions are transported to courtyards. The results provide urban planners direct information to reduce air pollution by proper structural layout of perimeter blocks.

Performance of personalized ventilation in a room with an underfloor air distribution system: transport of contaminants between occupants

DEFF Research Database (Denmark)

Cermak, Radim; Melikov, Arsen Krikor

2003-01-01

the workplaces has not been studied in detail. This paper presents a study on the performance of a personalized ventilation system installed in a full-scale test room with an underfloor air distribution system. Transport of human-produced airborne pollutants (in real life they can be infectious agents) between......Studies have documented that personalized ventilation, which provides clean air at each office workplace, is able to improve substantially the quality of air inhaled by occupants. However, the interaction between the airflow generated by personalized ventilation and the airflow pattern outside...... two occupants was examined using a tracer-gas. Two breathing thermal manikins were used to simulate occupants. The results show that the tested combination of personalized and underfloor ventilation was not able to decrease concentration of the human-produced airborne pollutants in air inhaled...

Novel bed integrated ventilation method for hospital patient rooms

DEFF Research Database (Denmark)

Bivolarova, Mariya Petrova; Melikov, Arsen Krikor; Kokora, Monika

2014-01-01

This study presents a novel method for advanced ventilation of hospital wards leading to improved air quality at reduced ventilation rate. The idea is to evacuate the bio-effluents generated from patients’ body by local exhaustion before being spread in the room. This concept was realized by using...... a mattress having a suction opening from which bio-effluents generated from human body are exhausted. Experiments were conducted in a full-scale two-bed hospital room mock-up, 4.7 x 5.3 x 2.6 m3 (W x L x H). Only one of the patients’ beds was equipped with the ventilated mattress. The room was air...... conditioned via mixing total volume ventilation system supplying air through a ceiling mounted diffuser. All experiments were performed at room air temperature of 23ºC. A thermal manikin was used to simulate a polluting patient on the bed equipped with the ventilated mattress. Two heated dummies were used...

Measurements of waste tank passive ventilation rates using tracer gases

International Nuclear Information System (INIS)

Huckaby, J.L.; Olsen, K.B.; Sklarew, D.S.; Evans, J.C.; Remund, K.M.

1997-09-01

This report presents the results of ventilation rate studies of eight passively ventilated high-level radioactive waste tanks using tracer gases. Head space ventilation rates were determined for Tanks A-101, AX-102, AX-103, BY-105, C-107, S-102, U-103, and U-105 using sulfur hexafluoride (SF 6 ) and/or helium (He) as tracer gases. Passive ventilation rates are needed for the resolution of several key safety issues. These safety issues are associated with the rates of flammable gas production and ventilation, the rates at which organic salt-nitrate salt mixtures dry out, and the estimation of organic solvent waste surface areas. This tracer gas study involves injecting a tracer gas into the tank headspace and measuring its concentration at different times to establish the rate at which the tracer is removed by ventilation. Tracer gas injection and sample collection were performed by SGN Eurisys Service Corporation and/or Lockheed Martin Hanford Corporation, Characterization Project Operations. Headspace samples were analyzed for He and SF 6 by Pacific Northwest National Laboratory (PNNL). The tracer gas method was first demonstrated on Tank S-102. Tests were conducted on Tank S-102 to verify that the tracer gas was uniformly distributed throughout the tank headspace before baseline samples were collected, and that mixing was sufficiently vigorous to maintain an approximately uniform distribution of tracer gas in the headspace during the course of the study. Headspace samples, collected from a location about 4 in away from the injection point and 15, 30, and 60 minutes after the injection of He and SF 6 , indicated that both tracer gases were rapidly mixed. The samples were found to have the same concentration of tracer gases after 1 hour as after 24 hours, suggesting that mixing of the tracer gas was essentially complete within 1 hour

Air Distribution in a Room and Design Considerations of Mixing Ventilation by Flow Elements

DEFF Research Database (Denmark)

Nielsen, Peter V.; Jensen, Rasmus Lund; Pedersen, D. N.

2001-01-01

The paper shows detailed measurements of the air distribution in a room ventilated by mixing ventilation according to the specifications given by the International Energy Agency work. (Energy Conservation in Buildings and Community Systems Programme, Annex 20). It describes a number of flow...

A numerical study on the performance evaluation of ventilation systems for indoor radon reduction

Energy Technology Data Exchange (ETDEWEB)

Lee, Ji Eun; Park, Hoon Chae; Choi, Hang Seok; Cho, Seung Yeon; Jeong, Tae Young; Roh, Sung Cheoul [Yonsei University, Wonju (Korea, Republic of)

2016-03-15

Numerical simulations were conducted using computational fluid dynamics to evaluate the effect of ventilation conditions on radon ({sup 222}Rn) reduction performance in a residential building. The results indicate that at the same ventilation rate, a mechanical ventilation system is more effective in reducing indoor radon than a natural ventilation system. For the same ventilation type, the indoor radon concentration decreases as the ventilation rate increases. When the air change per hour (ACH) was 1, the indoor radon concentration was maintained at less than 100 Bq/m{sup 3}. However, when the ACH was lowered to 0.01, the average indoor radon concentration in several rooms exceeded 148 Bq/ m{sup 3}. The angle of the inflow air was found to affect the indoor air stream and consequently the distribution of the radon concentration. Even when the ACH was 1, the radon concentrations of some areas were higher than 100 Bq/m{sup 3} for inflow air angles of 5 .deg. and 175 .deg.

Impact of ventilation/pressurization on indoor air contaminants in schools

International Nuclear Information System (INIS)

Shaughnessy, R.J.; Levetin, E.; Fisher, E.J.; Ligman, B.K.

1993-01-01

As part of a continuing technology development effort to control radon in schools, The U.S. Environmental Protection Agency's (EPA) School Evaluation Program (SEP) team in cooperation with U.S. EPA's Region 6 office has performed radon mitigation in two Southwestern United States schools utilizing the method of ventilation/pressurization control technology. Schools were inspected and IAQ measurements made with respect to carbon dioxide, bioaerosols, volatile organic compounds, and respirable particles. Premitigation results indicated poor ventilation conditions existed throughout the school buildings. Elevated levels of respirable particles were measured, yet no conclusions with respect to health could be implied. Post-mitigation results support, but do not prove the hypothesis that improved ventilation to control radon will also reduce other indicator indoor air contaminants. (orig.). (9 refs., 4 tabs.)

Improved inhaled air quality at reduced ventilation rate by control of airflow interaction at the breathing zone with lobed jets

DEFF Research Database (Denmark)

Bolashikov, Zhecho Dimitrov; Melikov, Arsen Krikor; Spilak, Michal

2014-01-01

Inhaled air quality at a reduced supply of clean air was studied by controlling the airflow interaction at the breathing zone of a person using lobed jets as part of personalized ventilation (PV). Experiments were performed in a full-scale test room at 23°C (73.4°F) with a breathing thermal manikin...... seated at a workstation, with realistic free-convection flow around the body and a normal breathing cycle. The air in the room was mixed with tracer gas R134a. Clean air was supplied isothermally from three nozzles with circular, four-leafed clover, and six-edged star openings of 0.025 m (0.08 ft...... over the interaction between the inserted jets and the free convection flow was efficient. Over 80% clean PV air was measured in inhalation. The worst performing nozzle was the four-leafed clover: its best performance yielded 23% clean air inhalation, at the shortest distance and the highest velocity...

A study on the evaluation of ventilation system suitable for outside air cooling applied in large data center for energy conservation

International Nuclear Information System (INIS)

Kwon, Yong Il

2016-01-01

In developed countries, expansion of communication technology has resulted in continual increase in the construction of data centers with high-density cooling loads. Throughout a year, IT equipment installed in a data center generates large and constant cooling load. As a result, data centers may be consuming an ever-growing amount of energy. The cooling system utilizing the energy of outside air is applied universally to reduce data center energy consumption. The application of the cooling system to the outdoor air cooling system of a data center considers that temperature efficiency and ventilation performance vary depending on the type of ventilation system. The displacement and mixed ventilation method can be applied generally to a data center. The efficiency of a ventilation system depends on inside temperature or contaminant concentrations in room and outlets. This study thus aims to evaluate the ventilation performance that varies according to type of ventilation system installed in the data center. Ventilation efficiency is assessed by applying the concept of total air age and considers the fresh air ratio and age of return air. Further, temperature efficiency gained by utilizing temperature difference is used to assess causes for changes in ventilation performance.

A study on the evaluation of ventilation system suitable for outside air cooling applied in large data center for energy conservation

Energy Technology Data Exchange (ETDEWEB)

Kwon, Yong Il [Shinhan University, Euijungbu (Korea, Republic of)

2016-05-15

In developed countries, expansion of communication technology has resulted in continual increase in the construction of data centers with high-density cooling loads. Throughout a year, IT equipment installed in a data center generates large and constant cooling load. As a result, data centers may be consuming an ever-growing amount of energy. The cooling system utilizing the energy of outside air is applied universally to reduce data center energy consumption. The application of the cooling system to the outdoor air cooling system of a data center considers that temperature efficiency and ventilation performance vary depending on the type of ventilation system. The displacement and mixed ventilation method can be applied generally to a data center. The efficiency of a ventilation system depends on inside temperature or contaminant concentrations in room and outlets. This study thus aims to evaluate the ventilation performance that varies according to type of ventilation system installed in the data center. Ventilation efficiency is assessed by applying the concept of total air age and considers the fresh air ratio and age of return air. Further, temperature efficiency gained by utilizing temperature difference is used to assess causes for changes in ventilation performance.

Mine ventilation engineering

Energy Technology Data Exchange (ETDEWEB)

Hall, C.J.

1981-01-01

This book on mine ventilation covers psychometrics, airflow through roadways and ducts, natural ventilation, fans, instruments, ventilation surveys, auxiliary ventilation, air quality, and planning and economics.

Minute ventilation of cyclists, car and bus passengers: an experimental study

Directory of Open Access Journals (Sweden)

Hazel Peter

2009-10-01

Full Text Available Abstract Background Differences in minute ventilation between cyclists, pedestrians and other commuters influence inhaled doses of air pollution. This study estimates minute ventilation of cyclists, car and bus passengers, as part of a study on health effects of commuters' exposure to air pollutants. Methods Thirty-four participants performed a submaximal test on a bicycle ergometer, during which heart rate and minute ventilation were measured simultaneously at increasing cycling intensity. Individual regression equations were calculated between heart rate and the natural log of minute ventilation. Heart rates were recorded during 280 two hour trips by bicycle, bus and car and were calculated into minute ventilation levels using the individual regression coefficients. Results Minute ventilation during bicycle rides were on average 2.1 times higher than in the car (individual range from 1.3 to 5.3 and 2.0 times higher than in the bus (individual range from 1.3 to 5.1. The ratio of minute ventilation of cycling compared to travelling by bus or car was higher in women than in men. Substantial differences in regression equations were found between individuals. The use of individual regression equations instead of average regression equations resulted in substantially better predictions of individual minute ventilations. Conclusion The comparability of the gender-specific overall regression equations linking heart rate and minute ventilation with one previous American study, supports that for studies on the group level overall equations can be used. For estimating individual doses, the use of individual regression coefficients provides more precise data. Minute ventilation levels of cyclists are on average two times higher than of bus and car passengers, consistent with the ratio found in one small previous study of young adults. The study illustrates the importance of inclusion of minute ventilation data in comparing air pollution doses between

Minute ventilation of cyclists, car and bus passengers: an experimental study.

Science.gov (United States)

Zuurbier, Moniek; Hoek, Gerard; van den Hazel, Peter; Brunekreef, Bert

2009-10-27

Differences in minute ventilation between cyclists, pedestrians and other commuters influence inhaled doses of air pollution. This study estimates minute ventilation of cyclists, car and bus passengers, as part of a study on health effects of commuters' exposure to air pollutants. Thirty-four participants performed a submaximal test on a bicycle ergometer, during which heart rate and minute ventilation were measured simultaneously at increasing cycling intensity. Individual regression equations were calculated between heart rate and the natural log of minute ventilation. Heart rates were recorded during 280 two hour trips by bicycle, bus and car and were calculated into minute ventilation levels using the individual regression coefficients. Minute ventilation during bicycle rides were on average 2.1 times higher than in the car (individual range from 1.3 to 5.3) and 2.0 times higher than in the bus (individual range from 1.3 to 5.1). The ratio of minute ventilation of cycling compared to travelling by bus or car was higher in women than in men. Substantial differences in regression equations were found between individuals. The use of individual regression equations instead of average regression equations resulted in substantially better predictions of individual minute ventilations. The comparability of the gender-specific overall regression equations linking heart rate and minute ventilation with one previous American study, supports that for studies on the group level overall equations can be used. For estimating individual doses, the use of individual regression coefficients provides more precise data. Minute ventilation levels of cyclists are on average two times higher than of bus and car passengers, consistent with the ratio found in one small previous study of young adults. The study illustrates the importance of inclusion of minute ventilation data in comparing air pollution doses between different modes of transport.

Ventilation of carbon monoxide from a biomass pellet storage tank--a study of the effects of variation of temperature and cross-ventilation on the efficiency of natural ventilation.

Science.gov (United States)

Emhofer, Waltraud; Lichtenegger, Klaus; Haslinger, Walter; Hofbauer, Hermann; Schmutzer-Roseneder, Irene; Aigenbauer, Stefan; Lienhard, Martin

2015-01-01

Wood pellets have been reported to emit toxic gaseous emissions during transport and storage. Carbon monoxide (CO) emission, due to the high toxicity of the gas and the possibility of it being present at high levels, is the most imminent threat to be considered before entering a pellet storage facility. For small-scale (ventilation, preferably natural ventilation utilizing already existing openings, has become the most favored solution to overcome the problem of high CO concentrations. However, there is little knowledge on the ventilation rates that can be reached and thus on the effectiveness of such measures. The aim of the study was to investigate ventilation rates for a specific small-scale pellet storage system depending on characteristic temperature differences. Furthermore, the influence of the implementation of a chimney and the influence of cross-ventilation on the ventilation rates were investigated. The air exchange rates observed in the experiments ranged between close to zero and up to 8 m(3) h(-1), depending largely on the existing temperature differences and the existence of cross-ventilation. The results demonstrate that implementing natural ventilation is a possible measure to enhance safety from CO emissions, but not one without limitations. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Cooling energy efficiency and classroom air environment of a school building operated by the heat recovery air conditioning unit

International Nuclear Information System (INIS)

Wang, Yang; Zhao, Fu-Yun; Kuckelkorn, Jens; Liu, Di; Liu, Li-Qun; Pan, Xiao-Chuan

2014-01-01

The recently-built school buildings have adopted novel heat recovery ventilator and air conditioning system. Heat recovery efficiency of the heat recovery facility and energy conservation ratio of the air conditioning unit were analytically modeled, taking the ventilation networks into account. Following that, school classroom displacement ventilation and its thermal stratification and indoor air quality indicated by the CO 2 concentration have been numerically modeled concerning the effects of delivering ventilation flow rate and supplying air temperature. Numerical results indicate that the promotion of mechanical ventilation rate can simultaneously boost the dilution of indoor air pollutants and the non-uniformity of indoor thermal and pollutant distributions. Subsequent energy performance analysis demonstrates that classroom energy demands for ventilation and cooling could be reduced with the promotion of heat recovery efficiency of the ventilation facility, and the energy conservation ratio of the air conditioning unit decreases with the increasing temperatures of supplying air. Fitting correlations of heat recovery ventilation and cooling energy conservation have been presented. - Highlights: • Low energy school buildings and classroom environment. • Heat recovery facility operating with an air conditioning unit. • Displacement ventilation influenced by the heat recovery efficiency. • Energy conservation of cooling and ventilation through heat recovery. • Enhancement of classroom environment with reduction of school building energy

Solutions for Energy Efficient and Sustainable Heating of Ventilation Air: A Review

Directory of Open Access Journals (Sweden)

A. Žandeckis

2015-10-01

Full Text Available A high energy efficiency and sustainability standards defined by modern society and legislation requires solutions in the form of complex integrated systems. The scope of this work is to provide a review on technologies and methods for the heating of ventilation air as a key aspect for high energy and environmental performance of buildings located in a cold climate. The results of this work are more relevant in the buildings where space heating consumes a significant part of the energy balance of a building, and air exchange is arranged in an organized manner. A proper design and control strategy, heat recovery, the use of renewable energy sources, and waste heat are the main aspects which must be considered for efficient and sustainable ventilation. This work focuses on these aspects. Air conditioning is not in the scope of this study.

A preliminary investigation of indoor air quality in a naturally ventilated house

International Nuclear Information System (INIS)

Shahrani, S.; Ahmed, A.Z.; Abdul Rahman, S.

2006-01-01

Continuous monitoring of indoor air quality was conducted in a naturally ventilated Malaysian house. CO 2 , CO, temperature and relative air humidity measurements were performed in the bathroom, bedroom, family room, kitchen and living room at 15-minute intervals over a 24-hour monitoring period. The measurement data were supplemented with time activity diaries detailing the occupants time of occupancy in each room, activities undertaken in each room and cooling and/or ventilation techniques used in each room. Indoor air quality was found to be generally satisfactory in all five rooms. However, levels of CO in the family room exceeded the USEPA, WHO and Singapore guidelines. Additionally, levels of relative humidity in the kitchen, living room and family room temperature in all five rooms exceeded the ASHRAE and Singapore guidelines, and suggest the like hood of condensation and mould growth

Comparison of indoor air distribution and thermal environment for different combinations of radiant heating systems with mechanical ventilation systems

DEFF Research Database (Denmark)

Wu, Xiaozhou; Fang, Lei; Olesen, Bjarne W.

2018-01-01

A hybrid system with a radiant heating system and a mechanical ventilation system, which is regarded as an advanced heating, ventilation and air-conditioning (HVAC) system, has been applied in many modern buildings worldwide. To date, almost no studies focused on comparative analysis of the indoor...... air distribution and the thermal environment for all combinations of radiant heating systems with mechanical ventilation systems. Therefore, in this article, the indoor air distribution and the thermal environment were comparatively analyzed in a room with floor heating (FH) or ceiling heating (CH......) and mixing ventilation (MV) or displacement ventilation (DV) when the supply air temperature ranged from 15.0°C to 19.0°C. The results showed that the temperature effectiveness values were 1.05–1.16 and 0.95–1.02 for MV+ FH and MV+ CH, respectively, and they were 0.78–0.91 and 0.51–0.67 for DV + FH and DV...

Capturing energy from ventilation air methane a preliminary design for a new approach

International Nuclear Information System (INIS)

Cluff, D.L.; Kennedy, G.A.; Bennett, J.G.; Foster, P.J.

2015-01-01

Methane is a potent greenhouse gas (GHG), discharged to the atmosphere by coalmining, the natural gas industry and natural biological processes, second only to carbon dioxide; thus, any reduction in atmospheric methane would be globally beneficial. The capture or use of ventilation air methane (VAM) is challenging because it is a high volume low concentration methane source. This results in the routine discharge of methane into the atmosphere. A review of VAM mitigation technologies is provided and the main disadvantages of the existing technologies are discussed. In the proposed VamTurBurner © system, the heat from the combustion chamber is transferred to the preheating zone either by a heat exchanger or by redirecting the combustion products to mix with the ventilation air stream from a coalmine. Gas turbines (GT) are used to produce electricity with the exhaust gases directed to mix with the incoming ventilation airflow. The turbulence introduced by the GT exhaust assists with mixing of the incoming ventilation airflow and the return flow of combustion products from the combustion chamber. The combustion products are a source of heat, which increases the temperature of the incoming ventilation air to a value high enough for the methane to undergo flameless combustion upon encountering the igniters. The high temperature combustion products enter a multi-generation system. The multi-generation system is based on mature engineering technology such as heat exchangers and steam turbines. The residual heat provides additional heat based products such as industrial scale drying, chilling by an absorption chiller or simply hot water. The VamTurBurner © uses the energy from the GT, igniters and VAM to provide clean efficient energy while mitigating the atmospheric emissions of methane. The opportunity to collect carbon credits may improve the economics. Since the VAM is a free energy source, the output of the system is greater than the purchased energy. - Highlights: �

Rational use of supply air in residential buildings

DEFF Research Database (Denmark)

Mortensen, Dorthe Kragsig; Nielsen, Toke Rammer; Svendsen, Svend

2009-01-01

The ventilation rate influences the air quality by determining the intensity of pollution sources. This paper compared the intensity of the sensory pollution during occupied hours in an apartment ventilated by a constant air volume system and demand controlled ventilation systems controlled by oc...... by occupancy. The systems supplied the same total volume of air daily. It was found that the supply air could be used more rationally by redistributing it according to occupancy compared to maintaining a constant ventilation rate during all hours....

Environmental Technology Verification: Supplement to Test/QA Plan for Biological and Aerosol Testing of General Ventilation Air Cleaners; Bioaerosol Inactivation Efficiency by HVAC In-Duct Ultraviolet Light Air Cleaners

Science.gov (United States)

The Air Pollution Control Technology Verification Center has selected general ventilation air cleaners as a technology area. The Generic Verification Protocol for Biological and Aerosol Testing of General Ventilation Air Cleaners is on the Environmental Technology Verification we...

Boundary conditions for natural supply ventilation

NARCIS (Netherlands)

Jansen, D.W.L.; Loomans, M.G.L.C.; Wit, de M.H.; Zeiler, W.; Seppänen, O.; Säteri, J.

2007-01-01

The development of an air jet from a controlled natural ventilation grill for different outdoor conditions is studied. Extensive laboratory measurements are taken in different situations, while the air flow rate through the grill is kept constant. The grill setting and supply temperature are varied.

Design of energy efficient ventilation and air-conditioning systems

CERN Document Server

Seppänen, Olli; Bertilsson, Thore; Maripuu, Mari-Liis; Lamy, Hervé; Vanden Borre, Alex

2012-01-01

This guidebook covers numerous system components of ventilation and air-conditioning systems and shows how they can be improved by applying the latest technology products. Special attention is paid to details, which are often overlooked in the daily design practice, resulting in poor performance of high quality products once they are installed in the building system.

Hybrid Ventilation Air Flow Process

DEFF Research Database (Denmark)

Heiselberg, Per Kvols

The scope of this annex is therefore to obtain better knowledge of the use of hybrid ventilation technologies. The annex focus on development of control strategies for hybrid ventilation, on development of methods to predict hybrid ventilation performance in office buildings and on implementation...

Economic, Environmental and Health Implications of Enhanced Ventilation in Office Buildings.

Science.gov (United States)

MacNaughton, Piers; Pegues, James; Satish, Usha; Santanam, Suresh; Spengler, John; Allen, Joseph

2015-11-18

Current building ventilation standards are based on acceptable minimums. Three decades of research demonstrates the human health benefits of increased ventilation above these minimums. Recent research also shows the benefits on human decision-making performance in office workers, which translates to increased productivity. However, adoption of enhanced ventilation strategies is lagging. We sought to evaluate two of the perceived potential barriers to more widespread adoption-Economic and environmental costs. We estimated the energy consumption and associated per building occupant costs for office buildings in seven U.S. cities, representing different climate zones for three ventilation scenarios (standard practice (20 cfm/person), 30% enhanced ventilation, and 40 cfm/person) and four different heating, ventilation and air conditioning (HVAC) system strategies (Variable Air Volume (VAV) with reheat and a Fan Coil Unit (FCU), both with and without an energy recovery ventilator). We also estimated emissions of greenhouse gases associated with this increased energy usage, and, for comparison, converted this to the equivalent number of vehicles using greenhouse gas equivalencies. Lastly, we paired results from our previous research on cognitive function and ventilation with labor statistics to estimate the economic benefit of increased productivity associated with increasing ventilation rates. Doubling the ventilation rate from the American Society of Heating, Refrigeration and Air-Conditioning Engineers minimum cost less than $40 per person per year in all climate zones investigated. Using an energy recovery ventilation system significantly reduced energy costs, and in some scenarios led to a net savings. At the highest ventilation rate, adding an ERV essentially neutralized the environmental impact of enhanced ventilation (0.03 additional cars on the road per building across all cities). The same change in ventilation improved the performance of workers by 8

Economic, Environmental and Health Implications of Enhanced Ventilation in Office Buildings

Directory of Open Access Journals (Sweden)

Piers MacNaughton

2015-11-01

Full Text Available Introduction: Current building ventilation standards are based on acceptable minimums. Three decades of research demonstrates the human health benefits of increased ventilation above these minimums. Recent research also shows the benefits on human decision-making performance in office workers, which translates to increased productivity. However, adoption of enhanced ventilation strategies is lagging. We sought to evaluate two of the perceived potential barriers to more widespread adoption—Economic and environmental costs. Methods: We estimated the energy consumption and associated per building occupant costs for office buildings in seven U.S. cities, representing different climate zones for three ventilation scenarios (standard practice (20 cfm/person, 30% enhanced ventilation, and 40 cfm/person and four different heating, ventilation and air conditioning (HVAC system strategies (Variable Air Volume (VAV with reheat and a Fan Coil Unit (FCU, both with and without an energy recovery ventilator. We also estimated emissions of greenhouse gases associated with this increased energy usage, and, for comparison, converted this to the equivalent number of vehicles using greenhouse gas equivalencies. Lastly, we paired results from our previous research on cognitive function and ventilation with labor statistics to estimate the economic benefit of increased productivity associated with increasing ventilation rates. Results: Doubling the ventilation rate from the American Society of Heating, Refrigeration and Air-Conditioning Engineers minimum cost less than $40 per person per year in all climate zones investigated. Using an energy recovery ventilation system significantly reduced energy costs, and in some scenarios led to a net savings. At the highest ventilation rate, adding an ERV essentially neutralized the environmental impact of enhanced ventilation (0.03 additional cars on the road per building across all cities. The same change in ventilation

Liquid Ventilation

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Qutaiba A. Tawfic

2011-01-01

Full Text Available Mammals have lungs to breathe air and they have no gills to breath liquids. When the surface tension at the air-liquid interface of the lung increases, as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen, as the inert carrier of oxygen and carbon dioxide offers a number of theoretical advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. The potential for multiple clinical applications for liquid-assisted ventilation will be clarified and optimized in future. Keywords: Liquid ventilation; perfluorochemicals; perfluorocarbon; respiratory distress; surfactant.

Effect of a ventilator-focused intervention on the rate of Acinetobacter baumannii infection among ventilated patients.

Science.gov (United States)

Cohen, Regev; Shimoni, Zvi; Ghara, Riad; Ram, Ron; Ben-Ami, Ronen

2014-09-01

Acinetobacter baumannii is a leading cause of ventilator-associated pneumonia, often as a result of ventilator equipment contamination. Evidence-based guidance on optimal care of ventilator equipment to prevent infection is lacking. Here, we report on a significant and persistent reduction in A baumannii infection rates achieved by introducing a strict policy on ventilator care. We implemented an institution-wide ventilator care policy that included routine exchange of breathing circuits and external bacterial filters (every 7-14 days) and replacement followed by routine sterilization of internal bacterial filters (every 4-8 weeks). We analyzed sputum cultures and patient outcomes among ventilated patients before and after the intervention. Between January 2012 and March 2013, 321 patients ventilated for more than 3 days comprised the study cohort. Health care-associated A baumannii acquisition was significantly reduced during the postintervention period (33% vs 16%; odds ratio, 0.39; 95% confidence interval, 0.23-0.67; P = .0008). Additionally, the median time to A baumannii acquisition was significantly longer postintervention (59 vs 21 days; P < .0001). A baumannii ventilator-associated pneumonia risk was also reduced postintervention (odds ratio, 0.39; P = .005). Implementing a stricter standard of ventilator care than that currently defined in published guidelines can significantly decrease health care-associated A baumannii acquisition and related adverse outcomes among ventilated patients. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Design and simulation of a hybrid ventilation system with earth-air heat exchanger

Energy Technology Data Exchange (ETDEWEB)

Athienitis, A.K.; Zhao, M. [Concordia Univ., Centre for Building Studies, Montreal, PQ (Canada). Dept. of Building, Civil and Environmental Engineering; Roy, M. [Martin Roy and Associes Group Conseil Inc., Montreal, PQ (Canada)

2005-07-01

A simulation study was conducted during the design phase of a new circus building in Montreal which includes a hybrid ventilation system through which fresh air is supplied from an earth-air heat exchanger (EAHE). The EAHE has the potential to satisfy the cooling needs of the building and can also be used to preheat fresh air, thereby satisfying one-third or more of the building's heating needs. Another feature of the building is that it uses displacement ventilation by which the air is supplied at low velocities through large diffusers behind the top level seats or under the seats. In this study, computational fluid dynamics (CFD) simulations were carried out to help size the supply and return units of the heating, ventilating and air conditioning (HVAC) system, as well as the exhaust chimney. The primary objective of the CFD simulation was to determine the maximum velocity and temperature in the seated area to ensure thermal comfort. CFD simulation predictions were found to be in good agreement with preliminary measurements taken in the building. In order to monitor the operation of the system over the next year, the underground ducts were equipped with temperature sensors at several depths into the soil. The energy efficiency of the hybrid HVAC system will be assessed and the velocity and temperature distribution in the theatre will be examined under various operating and energy load conditions. 8 refs., 6 figs.

The performance of Dräger Oxylog ventilators at simulated altitude.

Science.gov (United States)

Flynn, J G; Singh, B

2008-07-01

Ventilated patients frequently require transport by air in a hypobaric environment. Previous studies have demonstrated significant changes in the performance of ventilators with changes in cabin pressure (altitude) but no studies have been published on the function of modem ventilators at altitude. This experiment set out to evaluate ventilatory parameters (tidal volume and respiratory rate) of three commonly used transport ventilators (the Dräger Oxylog 1000, 2000 and 3000) in a simulated hypobaric environment. Ventilators were assessed using either air-mix (60% oxygen) or 100% oxygen and tested against models simulating a normal lung, a low compliance (Acute Respiratory Distress Syndrome) lung and a high-resistance (asthma) lung. Ventilators were tested at a range of simulated altitudes between sea level and 3048 m. Over this range, tidal volume delivered by the Oxylog 1000 increased by 68% and respiratory rate decreased by 28%. Tidal volume delivered by the Oxylog 2000 ventilator increased by 29% over the same range of altitudes but there was no significant change in respiratory rate. Tidal volume and respiratory rate remained constant with the Oxylog 3000 over the same range of altitudes. Changes were consistent with each ventilator regardless of oxygen content or lung model. It is important that clinicians involved in critical care transport in a hypobaric environment are aware that individual ventilators perform differently at altitude and that they are aware of the characteristics of the particular ventilator that they are using.

On the influence of the ventilation rate to the radiation burden in dwellings

International Nuclear Information System (INIS)

Tschurlovits, M.

1980-01-01

Calculations on the influence of the ventilation rate to the concentration of radon in dwellings from radioactive material of natural origin in building material are completed with a few examples of measurements. In addition, the optimization of the ventilation rate and the consequences of poorly ventilated dwellings are reported briefly. (author)

Effects of Classroom Ventilation Rate and Temperature on Students' Test Scores.

Science.gov (United States)

Haverinen-Shaughnessy, Ulla; Shaughnessy, Richard J

2015-01-01

Using a multilevel approach, we estimated the effects of classroom ventilation rate and temperature on academic achievement. The analysis is based on measurement data from a 70 elementary school district (140 fifth grade classrooms) from Southwestern United States, and student level data (N = 3109) on socioeconomic variables and standardized test scores. There was a statistically significant association between ventilation rates and mathematics scores, and it was stronger when the six classrooms with high ventilation rates that were indicated as outliers were filtered (> 7.1 l/s per person). The association remained significant when prior year test scores were included in the model, resulting in less unexplained variability. Students' mean mathematics scores (average 2286 points) were increased by up to eleven points (0.5%) per each liter per second per person increase in ventilation rate within the range of 0.9-7.1 l/s per person (estimated effect size 74 points). There was an additional increase of 12-13 points per each 1°C decrease in temperature within the observed range of 20-25°C (estimated effect size 67 points). Effects of similar magnitude but higher variability were observed for reading and science scores. In conclusion, maintaining adequate ventilation and thermal comfort in classrooms could significantly improve academic achievement of students.

Experimental research on the indoor temperature and humidity fields in radiant ceiling air-conditioning system under natural ventilation

Science.gov (United States)

Huang, Tao; Xiang, Yutong; Wang, Yonghong

2017-05-01

In this paper, the indoor temperature and humidity fields of the air in a metal ceiling radiant panel air conditioning system with fresh air under natural ventilation were researched. The temperature and humidity distributions at different height and different position were compared. Through the computation analysis of partial pressure of water vapor, the self-recovery characteristics of humidity after the natural ventilation was discussed.

Occupant Interactions and Effectiveness of Natural Ventilation Strategies in Contemporary New Housing in Scotland, UK

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Tim Sharpe

2015-07-01

Full Text Available The need to reduce carbon emissions and fuel poverty has led to increased building envelope air tightness, intended to reduce uncontrolled ventilation heat losses. Ventilation strategies in dwellings still allow the use of trickle ventilators in window frames for background ventilation. The extent to which this results in “healthy” Indoor Air Quality (IAQ in recently constructed dwellings was a concern of regulators in Scotland. This paper describes research to explore this. First a review of literature was conducted, then data on occupant interactions with ventilation provisions (windows, doors, trickle vents gathered through an interview-based survey of 200 recently constructed dwellings, and measurements made on a sample of 40 of these. The main measured parameter discussed here is CO2 concentration. It was concluded after the literature review that 1000 ppm absolute was a reasonable threshold to use for “adequate” ventilation. The occupant survey found that there was very little occupant interaction with the trickle ventilators e.g., in bedrooms 63% were always closed, 28% always open, and in only 9% of cases occupants intervened to make occasional adjustments. In the measured dwellings average bedroom CO2 levels of 1520 ppm during occupied (night time hours were observed. Where windows were open the average bedroom CO2 levels were 972 ppm. With windows closed, the combination of “trickle ventilators open plus doors open” gave an average of 1021 ppm. “Trickle ventilators open” gave an average of 1571 ppm. All other combinations gave averages of 1550 to 2000 ppm. Ventilation rates and air change rates were estimated from measured CO2 levels, for all dwellings calculated ventilation rate was less than 8 L/s/p, in 42% of cases calculated air change rate was less than 0.5 ach. It was concluded that trickle ventilation as installed and used is ineffective in meeting desired ventilation rates, evidenced by high CO2 levels reported

Occupant Interactions and Effectiveness of Natural Ventilation Strategies in Contemporary New Housing in Scotland, UK.

Science.gov (United States)

Sharpe, Tim; Farren, Paul; Howieson, Stirling; Tuohy, Paul; McQuillan, Jonathan

2015-07-21

The need to reduce carbon emissions and fuel poverty has led to increased building envelope air tightness, intended to reduce uncontrolled ventilation heat losses. Ventilation strategies in dwellings still allow the use of trickle ventilators in window frames for background ventilation. The extent to which this results in "healthy" Indoor Air Quality (IAQ) in recently constructed dwellings was a concern of regulators in Scotland. This paper describes research to explore this. First a review of literature was conducted, then data on occupant interactions with ventilation provisions (windows, doors, trickle vents) gathered through an interview-based survey of 200 recently constructed dwellings, and measurements made on a sample of 40 of these. The main measured parameter discussed here is CO2 concentration. It was concluded after the literature review that 1000 ppm absolute was a reasonable threshold to use for "adequate" ventilation. The occupant survey found that there was very little occupant interaction with the trickle ventilators e.g., in bedrooms 63% were always closed, 28% always open, and in only 9% of cases occupants intervened to make occasional adjustments. In the measured dwellings average bedroom CO2 levels of 1520 ppm during occupied (night time) hours were observed. Where windows were open the average bedroom CO2 levels were 972 ppm. With windows closed, the combination of "trickle ventilators open plus doors open" gave an average of 1021 ppm. "Trickle ventilators open" gave an average of 1571 ppm. All other combinations gave averages of 1550 to 2000 ppm. Ventilation rates and air change rates were estimated from measured CO2 levels, for all dwellings calculated ventilation rate was less than 8 L/s/p, in 42% of cases calculated air change rate was less than 0.5 ach. It was concluded that trickle ventilation as installed and used is ineffective in meeting desired ventilation rates, evidenced by high CO2 levels reported across the sampled dwellings

Subway platform air quality: Assessing the influences of tunnel ventilation, train piston effect and station design

Science.gov (United States)

Moreno, T.; Pérez, N.; Reche, C.; Martins, V.; de Miguel, E.; Capdevila, M.; Centelles, S.; Minguillón, M. C.; Amato, F.; Alastuey, A.; Querol, X.; Gibbons, W.

2014-08-01

A high resolution air quality monitoring campaign (PM, CO2 and CO) was conducted on differently designed station platforms in the Barcelona subway system under: (a) normal forced tunnel ventilation, and (b) with daytime tunnel ventilation systems shut down. PM concentrations are highly variable (6-128 μgPM1 m-3, 16-314 μgPM3 m-3, and 33-332 μgPM10 m-3, 15-min averages) depending on ventilation conditions and station design. Narrow platforms served by single-track tunnels are heavily dependent on forced tunnel ventilation and cannot rely on the train piston effect alone to reduce platform PM concentrations. In contrast PM levels in stations with spacious double-track tunnels are not greatly affected when tunnel ventilation is switched off, offering the possibility of significant energy savings without damaging air quality. Sampling at different positions along the platform reveals considerable lateral variation, with the greatest accumulation of particulates occurring at one end of the platform. Passenger accesses can dilute PM concentrations by introducing cleaner outside air, although lateral down-platform accesses are less effective than those positioned at the train entry point. CO concentrations on the platform are very low (≤1 ppm) and probably controlled by ingress of traffic-contaminated street-level air. CO2 averages range from 371 to 569 ppm, changing during the build-up and exchange of passengers with each passing train.

Natural ventilation for reducing airborne infection in hospitals

Energy Technology Data Exchange (ETDEWEB)

Qian, Hua [School of Energy and Environment, Southeast University, Nanjing (China); Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong (China); Li, Yuguo; Ching, W.H.; Sun, H.Q. [Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong (China); Seto, W.H.; Ching, Patricia [Department of Microbiology, Queen Mary Hospital, Hong Kong (China)

2010-03-15

High ventilation rate is shown to be effective for reducing cross-infection risk of airborne diseases in hospitals and isolation rooms. Natural ventilation can deliver much higher ventilation rate than mechanical ventilation in an energy-efficient manner. This paper reports a field measurement of naturally ventilated hospital wards in Hong Kong and presents a possibility of using natural ventilation for infection control in hospital wards. Our measurements showed that natural ventilation could achieve high ventilation rates especially when both the windows and the doors were open in a ward. The highest ventilation rate recorded in our study was 69.0 ACH. The airflow pattern and the airflow direction were found to be unstable in some measurements with large openings. Mechanical fans were installed in a ward window to create a negative pressure difference. Measurements showed that the negative pressure difference was negligible with large openings but the overall airflow was controlled in the expected direction. When all the openings were closed and the exhaust fans were turned on, a reasonable negative pressure was created although the air temperature was uncontrolled. The high ventilation rate provided by natural ventilation can reduce cross-infection of airborne diseases, and thus it is recommended for consideration of use in appropriate hospital wards for infection control. Our results also demonstrated a possibility of converting an existing ward using natural ventilation to a temporary isolation room through installing mechanical exhaust fans. (author)

The impacts of balanced and exhaust mechanical ventilation on indoor radon

International Nuclear Information System (INIS)

Fisk, W.J.; Mowris, R.J.

1987-02-01

Models for estimating radon entry rates, indoor radon concentrations, and ventilation rates in houses with a basement or a vented crawl-space and ventilated by natural infiltration, mechanical exhaust ventilation, or balanced mechanical ventilation are described. Simulations are performed for a range of soil and housing characteristics using hourly weather data for the heating season in Spokane, WA. For a house with a basement, we show that any ventilation technique should be acceptable when the soil permeability is less than approximately 10 -12 m 2 . However, exhaust ventilation leads to substantially higher indoor radon concentrations than infiltration or balanced ventilation with the same average air exchange rate when the soil permeability is 10 -10 m 2 or greater. For houses with a crawl-space, indoor radon concentrations are lowest with balanced ventilation, intermediate with exhaust ventilation, and highest with infiltration

Building envelope design for renewal of air by natural ventilation in moderate climates. Proposition of a designing methodology; Conception des enveloppes de batiments pour le renouvellement d'air par ventilation naturelle en climats temperes. Proposition d'une methodologie de conception

Energy Technology Data Exchange (ETDEWEB)

Mansouri, Y.

2003-12-01

The subject of this research is to produce methods and methodological tools for the architects to support the integration of natural ventilation systems in the building envelope design. Our research is situated to the interface between the architectural practice and the physical research on natural ventilation. We are interested in phenomena that can influence or force the strategy of ventilation. A morphological analysis of naturally ventilated buildings concerning the integration modes of natural ventilation systems is done permitting US to propose a typology and a topology of ventilation systems. We define criteria in relation to the thermal comfort, to the quality of air and the economy of energy to assess air renewal techniques. In complement of the sizing tool, we elaborate a methodology of conception for the integration of passives ventilation systems. Design guidelines permit US to conclude on an effective natural ventilation system which is well adapted to collective habitat. (author)

Effectiveness of horizontal air flow fans supporting natural ventilation in a Mediterranean multi-span greenhouse

OpenAIRE

López, Alejandro; Valera, Diego Luis; Molina-Aiz, Francisco Domingo; Peña, Araceli

2013-01-01

Natural ventilation is the most important method of climate control in Mediterranean greenhouses. In this study, the microclimate and air flow inside a Mediterranean greenhouse were evaluated by means of sonic anemometry. Experiments were carried out in conditions of moderate wind (≈ 4.0 m s-1), and at low wind speed (≈ 1.8 m s-1) the natural ventilation of the greenhouse was supplemented by two horizontal air flow fans. The greenhouse is equipped with a single roof vent opening t...

Design of Air Ventilation System for Cargo Hold Vessels Using Solar Desiccant

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Alam Baheramsyah

2017-09-01

Full Text Available One of the facilities and infrastructure of the vessel is the ventilation system in the cargo hold to maintain the quality. One attempt to avoid high moisture ratios is to provide a dry air supply by using desiccants. The purpose of this thesis is to design the system of air ventilation with solar desiccant by analysis the calculation with decrease air humidity ratio after passing desiccant rotor as well as fulfillment needs of heater and cooling system using heat of exhaust gas and seawater as well as fulfillment of electricity need using solar energy. From the result of analysis obtain to provide air supply in the cargo hold of 437.5 m3 / hour, the specification of rotor desiccant has a diameter of 550 mm with thickness 200 mm to decrease ratio of outside air humidity equal to 83.1% become 46.5%. Dehumidification air temperature of 47.7oC will be lowered to 35oC by using the sea water cooling media. As for the reactivation air heater requirement of 24.292 kW would be to fulfilled by utilizing the exhaust power of 498.12 kW. And for the electric power needs of the syetm is 34,488 wp will be supplied from the total solar module is 33 units with 345 wp per-capacity.

Evaluation of Ventilation Strategies in New Construction Multifamily Buildings

Energy Technology Data Exchange (ETDEWEB)

Maxwell, S. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States); Berger, D. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States); Zuluaga, M. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States)

2014-07-01

In multifamily buildings, particularly in the Northeast, exhaust ventilation strategies are the norm as a means of meeting both local exhaust and whole-unit mechanical ventilation rates. The issue of where the "fresh" air is coming from is gaining significance as air-tightness standards for enclosures become more stringent. CARB researchers have found that most new high performance, multifamily housing in the Northeast use one of four strategies for ventilation: continuous exhaust only with no designated supply or make-up air source, continuous exhaust with ducted make-up air to apartments, continuous exhaust with supply through a make-up air device integral to the unit HVAC, and continuous exhaust with supply through a passive inlet device, such as a trickle vent. Insufficient information is available to designers on how these various systems are best applied. Product performance data are based on laboratory tests, but there is no guarantee that those conditions will exist consistently in the finished building. In this research project, CARB evaluated the four ventilation strategies in the field to validate system performance.

Operating theatre ventilation systems and microbial air contamination in total joint replacement surgery: results of the GISIO-ISChIA study.

Science.gov (United States)

Agodi, A; Auxilia, F; Barchitta, M; Cristina, M L; D'Alessandro, D; Mura, I; Nobile, M; Pasquarella, C

2015-07-01

Recent studies have shown a higher rate of surgical site infections in hip prosthesis implantation using unidirectional airflow ventilation compared with turbulent ventilation. However, these studies did not measure the air microbial quality of operating theatres (OTs), and assumed it to be compliant with the recommended standards for this ventilation technique. To evaluate airborne microbial contamination in OTs during hip and knee replacement surgery, and compare the findings with values recommended for joint replacement surgery. Air samplings were performed in 28 OTs supplied with unidirectional, turbulent and mixed airflow ventilation. Samples were collected using passive sampling to determine the index of microbial air contamination (IMA). Active sampling was also performed in some of the OTs. The average number of people in the OT and the number of door openings during the sampling period were recorded. In total, 1228 elective prosthesis procedures (60.1% hip and 39.9% knee) were included in this study. Of passive samplings performed during surgical activity in unidirectional airflow ventilation OTs (U-OTs) and mixed airflow OTs (M-OTs), 58.9% and 87.6% had IMA values >2, respectively. Of samplings performed during surgical activity in turbulent airflow OTs (T-OTs) and in turbulent airflow OTs with the surgical team wearing Steri-Shield Turbo Helmets (TH-OTs), 8.6% and 60% had IMA values ≤ 2, respectively. Positive correlation was found between IMA values and the number of people in the OT and the number of door openings (P systems always provide acceptable airborne bacterial counts. Copyright © 2015 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

Effect of central ventilation and air conditioner system on the concentration and health risk from airborne polycyclic aromatic hydrocarbons.

Science.gov (United States)

Lv, Jinze; Zhu, Lizhong

2013-03-01

Central ventilation and air conditioner systems are widely utilized nowadays in public places for air exchange and temperature control, which significantly influences the transfer of pollutants between indoors and outdoors. To study the effect of central ventilation and air conditioner systems on the concentration and health risk from airborne pollutants, a spatial and temporal survey was carried out using polycyclic aromatic hydrocarbons (PAHs) as agent pollutants. During the period when the central ventilation system operated without air conditioning (AC-off period), concentrations of 2-4 ring PAHs in the model supermarket were dominated by outdoor levels, due to the good linearity between indoor air and outdoor air (r(p) > 0.769, p air conditioner systems were working simultaneously (AC-on period), although the total levels of PAHs were increased, the concentrations and percentage of the particulate PAHs indoors declined significantly. The BaP equivalency (BaPeq) concentration indicated that utilization of air conditioning reduced the health risks from PAHs in the model supermarket.

Effects of Classroom Ventilation Rate and Temperature on Students' Test Scores.

Directory of Open Access Journals (Sweden)

Ulla Haverinen-Shaughnessy

Full Text Available Using a multilevel approach, we estimated the effects of classroom ventilation rate and temperature on academic achievement. The analysis is based on measurement data from a 70 elementary school district (140 fifth grade classrooms from Southwestern United States, and student level data (N = 3109 on socioeconomic variables and standardized test scores. There was a statistically significant association between ventilation rates and mathematics scores, and it was stronger when the six classrooms with high ventilation rates that were indicated as outliers were filtered (> 7.1 l/s per person. The association remained significant when prior year test scores were included in the model, resulting in less unexplained variability. Students' mean mathematics scores (average 2286 points were increased by up to eleven points (0.5% per each liter per second per person increase in ventilation rate within the range of 0.9-7.1 l/s per person (estimated effect size 74 points. There was an additional increase of 12-13 points per each 1°C decrease in temperature within the observed range of 20-25°C (estimated effect size 67 points. Effects of similar magnitude but higher variability were observed for reading and science scores. In conclusion, maintaining adequate ventilation and thermal comfort in classrooms could significantly improve academic achievement of students.

Effects of Classroom Ventilation Rate and Temperature on Students’ Test Scores

Science.gov (United States)

2015-01-01

Using a multilevel approach, we estimated the effects of classroom ventilation rate and temperature on academic achievement. The analysis is based on measurement data from a 70 elementary school district (140 fifth grade classrooms) from Southwestern United States, and student level data (N = 3109) on socioeconomic variables and standardized test scores. There was a statistically significant association between ventilation rates and mathematics scores, and it was stronger when the six classrooms with high ventilation rates that were indicated as outliers were filtered (> 7.1 l/s per person). The association remained significant when prior year test scores were included in the model, resulting in less unexplained variability. Students’ mean mathematics scores (average 2286 points) were increased by up to eleven points (0.5%) per each liter per second per person increase in ventilation rate within the range of 0.9–7.1 l/s per person (estimated effect size 74 points). There was an additional increase of 12–13 points per each 1°C decrease in temperature within the observed range of 20–25°C (estimated effect size 67 points). Effects of similar magnitude but higher variability were observed for reading and science scores. In conclusion, maintaining adequate ventilation and thermal comfort in classrooms could significantly improve academic achievement of students. PMID:26317643

Performance evaluation of ventilation radiators

International Nuclear Information System (INIS)

Myhren, Jonn Are; Holmberg, Sture

2013-01-01

A ventilation radiator is a combined ventilation and heat emission unit currently of interest due to its potential for increasing energy efficiency in exhaust-ventilated buildings with warm water heating. This paper presents results of performance tests of several ventilation radiator models conducted under controlled laboratory conditions. The purpose of the study was to validate results achieved by Computational Fluid Dynamics (CFD) in an earlier study and identify possible improvements in the performance of such systems. The main focus was on heat transfer from internal convection fins, but comfort and health aspects related to ventilation rates and air temperatures were also considered. The general results from the CFD simulations were confirmed; the heat output of ventilation radiators may be improved by at least 20% without sacrificing ventilation efficiency or thermal comfort. Improved thermal efficiency of ventilation radiators allows a lower supply water temperature and energy savings both for heating up and distribution of warm water in heat pumps or district heating systems. A secondary benefit is that a high ventilation rate can be maintained all year around without risk for cold draught. -- Highlights: ► Low temperature heat emitters are currently of interest due to their potential for increasing energy efficiency. ► A ventilation radiator is a combined ventilation and heat emission unit which can be adapted to low temperature heating systems. ► We examine how ventilation radiators can be made to be more efficient in terms of energy consumption and thermal comfort. ► Current work focuses on heat transfer mechanisms and convection fin configuration of ventilation radiators

Ventilation and air conditioning system in waste treatment and storage facilities

International Nuclear Information System (INIS)

Kinoshita, Hirotsugu; Sugawara, Kazushige.

1987-01-01

So far, the measures concerning the facilities for treating and storing radioactive wastes in nuclear fuel cycle in Japan were in the state which cannot be said to be sufficient. In order to cope with this situation, electric power companies constructed and operated radioactive waste concentration and volume reduction facilities, solid waste storing facilities for drums, high level solid waste storing facilities, spent fuel cask preserving facilities and so on successively in the premises of nuclear power stations, and for the wastes expected in future, the research and the construction plan of the facilities for treating and storing low, medium and high level wastes have been advanced. The ventilation and air conditioning system for these facilities is the important auxiliary system which has the mission of maintaining safe and pleasant environment in the facilities and lowering as far as possible the release of radioactive substances to outside. The outline of waste treatment and storage facilities is explained. The design condition, ventilation and air conditioning method, the features of respective waste treatment and storage facilities, and the problems for the future are described. Hereafter, mechanical ventilation system continues to be the main system, and filters become waste, while the exchange of filters is accompanied by the radiation exposure of workers. (Kako, I.)

Laboratory study on the cooling effect of flash water evaporative cooling technology for ventilation and air-conditioning of buildings

DEFF Research Database (Denmark)

Fang, Lei; Yuan, Shu; Yang, Jianrong

environments and the other simulated an air-conditioned indoor environment. The flash water evaporation cooling device was installed in the chamber that simulated indoor environment. The air from the chamber simulating outdoor environment was introduced into the cooling device and cooled by the flash water......, is effective for ventilation and air-conditioning in warm/hot and dry climate zones. The technology can provide fresh outdoor air with a temperature of 4 to 7 °C lower than room air temperature.......This paper presents a simple cooling technology using flash water evaporation. The technology combines a water atomizer with a plate heat exchanger used for heat recovery of a ventilation system. It is mainly used to cool the ventilation airflow from outdoors and is particularly suitable to be used...

In China, students in crowded dormitories with a low ventilation rate have more common colds: evidence for airborne transmission.

Directory of Open Access Journals (Sweden)

Yuexia Sun

Full Text Available OBJECTIVE: To test whether the incidence of common colds among college students in China is associated with ventilation rates and crowdedness in dormitories. METHODS: In Phase I of the study, a cross-sectional study, 3712 students living in 1569 dorm rooms in 13 buildings responded to a questionnaire about incidence and duration of common colds in the previous 12 months. In Phase II, air temperature, relative humidity and CO(2 concentration were measured for 24 hours in 238 dorm rooms in 13 buildings, during both summer and winter. Out-to indoor air flow rates at night were calculated based on measured CO(2 concentrations. RESULTS: In Phase I, 10% of college students reported an incidence of more than 6 common colds in the previous 12 months, and 15% reported that each infection usually lasted for more than 2 weeks. Students in 6-person dorm rooms were about 2 times as likely to have an incidence of common colds ≥6 times per year and a duration ≥2 weeks, compared to students in 3-person rooms. In Phase II, 90% of the measured dorm rooms had an out-to indoor air flow rate less than the Chinese standard of 8.3 L/s per person during the heating season. There was a dose-response relationship between out-to indoor air flow rate per person in dorm rooms and the proportion of occupants with annual common cold infections ≥6 times. A mean ventilation rate of 5 L/(s•person in dorm buildings was associated with 5% of self reported common cold ≥6 times, compared to 35% at 1 L/(s•person. CONCLUSION: Crowded dormitories with low out-to indoor airflow rates are associated with more respiratory infections among college students.

Ammonia emissions in tunnel-ventilated broiler houses

Directory of Open Access Journals (Sweden)

KAO Lima

2011-12-01

Full Text Available Gas production in broiler houses and their emissions are closely related to the microclimate established inside the house according to air temperature, humidity, and velocity. Therefore, the internal house environment is influenced by building typology and ventilation system. The objective of the present study was to evaluate ammonia emission rates in broiler houses equipped with different ventilation systems (negative or positive pressure and litter conditions (new or built-up. The environment of six commercial broiler houses was evaluated internal and external NH3 concentrations. Ventilation rates were recorded to estimate ammonia emission rates. The efficiency of circulation and exhaust fans was assessed, and higher ventilation rates were determined in negative-pressure houses due to the higher flow of the fans. Houses with new litter increased ammonia emission rates along the rearing period, indicating the relationship between gas emissions, bird age and ventilation rates, and presented a typical curve of NH3 emission increase. Negative-pressure houses with built-up litter presented higher emission rates during the first rearing week due to the high NH3 concentration during the brooding period, when the ventilation rates required to maintain chick thermal comfort are low. Although the results of the present study indicate an advantage of the positive-pressure systems as to gas emissions, further research is needed reduce gas emissions in broiler houses with negative-pressure systems.

Evaporation Controlled Emission in Ventilated Rooms

DEFF Research Database (Denmark)

Topp, Claus; Nielsen, Peter V.; Heiselberg, Per

-scale ventilated room when the emission is fully or partly evaporation controlled. The objective of the present research work has been to investigate the change of emission rates from small-scale experiments to full-scale ventilated rooms and to investigate the influence of the local air velocity field near......Emission of volatile organic compounds (VOCs) from materials is traditionally determined from tests carried out in small-scale test chambers. However, a difference in scale may lead to a difference in the measured emission rate in a small-scale test chamber and the actual emission rate in a full...

Duct corrosion in the ventilating air conditioning system for Main Control Room

International Nuclear Information System (INIS)

Yamada, Kohei; Kobayashi, Takashi; Minami, Akiko; Fukuba, Kazushi

2014-01-01

Higashidori Nuclear Power Station, start-of-operation in December 2005, is a relatively new plant. We decided to get original data of air duct condition to determine maintenance policy of air duct, because planned maintenance of air duct has never been done and the corrosion of air duct has occurred in other plant. In January 2014, we found a corrosion-hole at the downstream of the inlet damper in the ventilating air conditioning system for Main Control Room (MCR). We supposed that the cause of rapid corrosion is related to the characteristic environment of this site. (author)

Carbon Dioxide Detection and Indoor Air Quality Control.

Science.gov (United States)

Bonino, Steve

2016-04-01

When building ventilation is reduced, energy is saved because it is not necessary to heat or cool as much outside air. Reduced ventilation can result in higher levels of carbon dioxide, which may cause building occupants to experience symptoms. Heating or cooling for ventilation air can be enhanced by a DCV system, which can save energy while providing a comfortable environment. Carbon dioxide concentrations within a building are often used to indicate whether adequate fresh air is being supplied to the building. These DCV systems use carbon dioxide sensors in each space or in the return air and adjust the ventilation based on carbon dioxide concentration; the higher the concentration, the more people occupy the space relative to the ventilation rate. With a carbon dioxide sensor DCV system, the fresh air ventilation rate varies based on the number ofpeople in the space, saving energy while maintaining a safe and comfortable environment.

Test Protocol for Room-to-Room Distribution of Outside Air by Residential Ventilation Systems

Energy Technology Data Exchange (ETDEWEB)

Barley, C. D.; Anderson, R.; Hendron, B.; Hancock, E.

2007-12-01

This test and analysis protocol has been developed as a practical approach for measuring outside air distribution in homes. It has been used successfully in field tests and has led to significant insights on ventilation design issues. Performance advantages of more sophisticated ventilation systems over simpler, less-costly designs have been verified, and specific problems, such as airflow short-circuiting, have been identified.

Sustained Reduction of Ventilator-Associated Pneumonia Rates Using Real-Time Course Correction With a Ventilator Bundle Compliance Dashboard.

Science.gov (United States)

Talbot, Thomas R; Carr, Devin; Parmley, C Lee; Martin, Barbara J; Gray, Barbara; Ambrose, Anna; Starmer, Jack

2015-11-01

The effectiveness of practice bundles on reducing ventilator-associated pneumonia (VAP) has been questioned. To implement a comprehensive program that included a real-time bundle compliance dashboard to improve compliance and reduce ventilator-associated complications. DESIGN Before-and-after quasi-experimental study with interrupted time-series analysis. SETTING Academic medical center. In 2007 a comprehensive institutional ventilator bundle program was developed. To assess bundle compliance and stimulate instant course correction of noncompliant parameters, a real-time computerized dashboard was developed. Program impact in 6 adult intensive care units (ICUs) was assessed. Bundle compliance was noted as an overall cumulative bundle adherence assessment, reflecting the percentage of time all elements were concurrently in compliance for all patients. The VAP rate in all ICUs combined decreased from 19.5 to 9.2 VAPs per 1,000 ventilator-days following program implementation (Pdashboard was associated with significant sustained decreases in VAP rates and an increase in bundle compliance among adult ICU patients.

Effectiveness of air vapor barriers combined with ventilated crawlspaces in decreasing residential exposure to radon daughters to radon daughters: preliminary report

International Nuclear Information System (INIS)

Sterling, T.D.; Arundel, A.; McIntyre, D.; Sterling, E.; Sterling, T.D.

1986-01-01

Radon gas is present in many homes. Concentrations may be increased in airtight, energy-efficient structures. This is especially true in cold climates where energy conservation is an important factor leading to the widespread application of sealing and tightening techniques both in older renovated homes and new construction. To reduce radon concentrations, it may be effective to ventilate crawlspaces and prevent infiltration of radon gas into the house by means of an air/vapor barrier. The authors report first results of comparing radon levels in homes with and without ventilated crawlspaces and air/vapor barriers. Radon emissions were measured in a tightly sealed home with ventilated crawlspaces and an air/vapor barrier and in two homes without such vapor barriers and ventilated crawlspaces, but differing in ventilation. Preliminary results suggest that use of ventilated crawlspaces and bottomside vapor barriers may reduce indoor radon levels by approximately 60%. 15 references, 1 table

Advanced Controls for Residential Whole-House Ventilation Systems

Energy Technology Data Exchange (ETDEWEB)

Turner, William [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Walker, Iain [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sherman, Max [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2014-08-01

Whole-house ventilation systems are becoming commonplace in new construction, remodeling/renovation, and weatherization projects, driven by combinations of specific requirements for indoor air quality (IAQ), health and compliance with standards, such as ASHRAE 62.2. Ventilation systems incur an energy penalty on the home via fan power used to drive the airflow, and the additional space-conditioning load associated with heating or cooling the ventilation air. Finding a balance between IAQ and energy use is important if homes are to be adequately ventilated while not increasing the energy burden. This study used computer simulations to examine RIVEC the Residential Integrated Ventilation Controller - a prototype ventilation controller that aims to deliver whole-house ventilation rates that comply with ventilation standards, for the minimum use of energy. Four different whole-house ventilation systems were simulated, both with and without RIVEC, so that the energy and IAQ results could be compared. Simulations were conducted for 13 US climate zones, three house designs, and three envelope leakage values. The results showed that the RIVEC controller could typically return ventilation energy savings greater than 40percent without compromising long-term chronic or short-term acute exposures to relevant indoor contaminants. Critical and average peak power loads were also reduced as a consequence of using RIVEC.

Evaluation of the Ventilation and Air Cleaning System Design Concepts for Safety Requirements during Fire Conditions in Nuclear Applications

International Nuclear Information System (INIS)

Rashad, S.; El-Fawal, M.; Kandil, M.

2013-01-01

The ventilation and air cleaning system in the nuclear or radiological installations is one of the essential nuclear safety concerns. It is responsible for confining the radioactive materials involved behind suitable barriers during normal and abnormal conditions. It must be designed to prevent the release of harmful products (radioactive gases, or airborne radioactive materials) from the system or facility, impacting the public or workers, and doing environmental damage. There are two important safety functions common to all ventilation and air cleaning system in nuclear facilities. They are: a) the requirements to maintain the pressure of the ventilated volume below that of surrounding, relatively non-active areas, in order to inhibit the spread of contamination during normal and abnormal conditions, and b) the need to treat the ventilated gas so as to minimize the release of any radioactive or toxic materials. Keeping the two important safety functions is achieved by applying the fire protection for the ventilation system to achieve safety and adequate protection in nuclear applications facilities during fire and accidental criticality conditions.The main purpose of this research is to assist ventilation engineers and experts in nuclear installations for safe operation and maintaining ventilation and air cleaning system during fire accident in nuclear facilities. The research focuses on fire prevention and protection of the ventilation systems in nuclear facilities. High-Efficiency particulate air (HEPA) filters are extremely susceptible to damage when exposed to the effects of fire, smoke, and water; it is the intent of this research to provide the designer with the experience gained over the years from hard lessons learned in protecting HEPA filters from fire. It describes briefly and evaluates the design safety features, constituents and working conditions of ventilation and air cleaning system in nuclear and radioactive industry.This paper provides and

Auxiliary mine ventilation manual

International Nuclear Information System (INIS)

Workplace Safety North

2010-01-01

An adequate ventilation system is needed for air quality and handling in a mine and is comprised of many different pieces of equipment for removing contaminated air and supplying fresh air and thereby provide a satisfactory working environment. This manual highlights auxiliary ventilation systems made up of small fans, ducts, tubes, air movers, deflectors and additional air flow controls which distribute fresh air delivered by the primary system to all areas. A review of auxiliary ventilation is provided. Design, operation and management issues are discussed and guidelines are furnished. This manual is limited to underground hard rock operations and does not address directly other, specific auxiliary systems, either in underground coal mines or uranium mines.

Auxiliary mine ventilation manual

Energy Technology Data Exchange (ETDEWEB)

Workplace Safety North

2010-07-01

An adequate ventilation system is needed for air quality and handling in a mine and is comprised of many different pieces of equipment for removing contaminated air and supplying fresh air and thereby provide a satisfactory working environment. This manual highlights auxiliary ventilation systems made up of small fans, ducts, tubes, air movers, deflectors and additional air flow controls which distribute fresh air delivered by the primary system to all areas. A review of auxiliary ventilation is provided. Design, operation and management issues are discussed and guidelines are furnished. This manual is limited to underground hard rock operations and does not address directly other, specific auxiliary systems, either in underground coal mines or uranium mines.

Diffuse Ceiling Ventilation

DEFF Research Database (Denmark)

Zhang, Chen; Heiselberg, Per; Nielsen, Peter V.

2014-01-01

As a novel air distribution system, diffuse ceiling ventilation combines the suspended acoustic ceiling with ventilation supply. Due to the low-impulse supply from the large ceiling area, the system does not generate draught when supplying cold air. However, heat sources play an important role...

Meeting Residential Ventilation Standards Through Dynamic Control of Ventilation Systems

OpenAIRE

Sherman, Max H.

2011-01-01

Existing ventilation standards, including American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) Standard 62.2, specify continuous operation of a defined mechanical ventilation system to provide minimum ventilation, with time-based intermittent operation as an option. This requirement ignores several factors and concerns including: other equipment such as household exhaust fans that might incidentally provide ventilation, negative impacts of ventilation when outd...

Ventilation of uranium mines

International Nuclear Information System (INIS)

Francois, Y.; Pradel, J.; Zettwoog, P.; Dumas, M.

1975-01-01

In the first part of the paper the authors describe the ventilation of French mines in terms of the primary ventilation system, which brings the outside air close to the working places using the overall structure of the mine to form the airways, and the secondary ventilation system, which is for the distribution of the primary air or for the ventilation of the development drifts and blind tunnels. Brief mention is made of the French regulations on the ventilation of mines in general and uranium mines in particular. The authors describe the equipment used and discuss the installed capacities and air flow per man and per working place. The difficulties encountered in properly ventilating various types of working places are mentioned, such as sublevel development drifts, reinforced stopes, and storage chambers with an artificial crown. The second part of the paper is devoted to computer calculations of the primary ventilation system. It is explained why the Commissariat a l'energie atomique has found it necessary to make these calculations. Without restating the mathematical theories underlying the methods employed, the authors demonstrate how simple measuring instruments and a small-size computer can be used to solve the ventilation problems arising in French mines. Emphasis is given to the layout of the ventilation system and to air flow and negative pressure measurements at the base of the mine. The authors show how calculations can be applied to new heading operations, a change in resistance, the replacement or addition of a ventilator, and a new air inlet or outlet. The authors come to the conclusion that since ventilation is at present the most reliable way of avoiding the pollution of mines, a thorough knowledge of the capabilities in this respect can often help improve working conditions. Despite the progress made, however, constant surveillance of the ventilation systems in uranium mines by a separate team with no responsibility for production problems is

Ventilation of uranium mines

International Nuclear Information System (INIS)

Francois, Y.; Pradel, J.; Zettwoog, P.; Dumas, M.

1975-01-01

In the first part of the paper the authors describe the ventilation of French mines in terms of the primary ventilation system, which brings the outside air close to the working places using the overall structure of the mine to form the airways, and the secondary ventilation system, which is for the distribution of the primary air or for the ventilation of the development drifts and blind tunnels. Brief mention is made of the French regulations on the ventilation of mines in general and uranium mines in particular. The authors describe the equipment used and discuss the installed capacities and air flow per man and per working place. The difficulties encountered in properly ventilating various types of working places are mentioned, such as sub-level development drifts, reinforced stopes, and storage chambers with an artificial crown. The second part of the paper is devoted to computer calculations of the primary ventilation system. It is explained why the Commissariat a l'energie atomique has found it necessary to make these calculations. Without restating the mathematical theories underlying the methods employed, the authors demonstrate how simple measuring instruments and a small-size computer can be used to solve the ventilation problems arising in French mines. Emphasis is given to the layout of the ventilation system and to air flow and negative pressure measurements at the base of the mine. The authors show how calculations can be applied to new heading operations, a change in resistance, the replacement or addition of a ventilator, and a new air inlet or outlet. The authors come to the conclusion that since ventilation is at present the most reliable way of avoiding the pollution of mines, a thorough knowledge of the capabilities in this respect can often help improve working conditions. Despite the progress made, however, constant surveillance of the ventilation systems in uranium mines by a separate team with no responsibility for production problems is

Quantifying the impact of traffic-related air pollution on the indoor air quality of a naturally ventilated building.

Science.gov (United States)

Tong, Zheming; Chen, Yujiao; Malkawi, Ali; Adamkiewicz, Gary; Spengler, John D

2016-01-01

Improper natural ventilation practices may deteriorate indoor air quality when in close proximity to roadways, although the intention is often to reduce energy consumption. In this study, we employed a CFD-based air quality model to quantify the impact of traffic-related air pollution on the indoor air quality of a naturally ventilated building. Our study found that the building envelope restricts dispersion and dilution of particulate matter. The indoor concentration in the baseline condition located 10m away from the roadway is roughly 16-21% greater than that at the edge of the roadway. The indoor flow recirculation creates a well-mixed zone with little variation in fine particle concentration (i.e., 253nm). For ultrafine particles (building, particle size, wind condition, and window size and location. A break-even point is observed at D'~2.1 (normalized distance from the roadway by the width of the road). The indoor particle concentration is greater than that at the highway where D'building planning, the distance from the roadway and the ambient wind condition need to be considered at the early design stage whereas the size and location of the window openings, the interior layout, and the placement of fresh air intakes are important to the indoor air quality of existing buildings adjacent to roadways. Copyright © 2016 Elsevier Ltd. All rights reserved.

Measuring Outdoor Air Intake Rates into Existing Building

Energy Technology Data Exchange (ETDEWEB)

Fisk, William; Sullivan, Douglas; Cohen, Sebastian; Han, Hwataik

2009-04-16

Practical and accurate technologies are needed for continuously measuring and controlling outdoor air (OA) intake rates in commercial building heating, ventilating, and air conditioning (HVAC) systems. This project evaluated two new measurement approaches. Laboratory experiments determined that OA flow rates were measurable with errors generally less than 10 percent using electronic air velocity probes installed between OA intake louver blades or at the outlet face of louvers. High accuracy was maintained with OA flow rates as low as 15 percent of the maximum for the louvers. Thus, with this measurement approach HVAC systems do not need separate OA intakes for minimum OA supply. System calibration parameters are required for each unique combination of louver type and velocity sensor location but calibrations are not necessary for each system installation. The research also determined that the accuracy of measuring OA flow rates with velocity probes located in the duct downstream of the intake louver was not improved by installing honeycomb airflow straighteners upstream of the probes. Errors varied with type of upstream louver, were as high as 100 percent, and were often greater than 25 percent. In conclusion, use of electronic air velocity probes between the blades of OA intake louvers or at the outlet face of louvers is a highly promising means of accurately measuring rates of OA flow into HVAC systems. The use of electronic velocity probes downstream of airflow straighteners is less promising, at least with the relatively small OA HVAC inlet systems employed in this research.

Lecture Notes on Mixing Ventilation

DEFF Research Database (Denmark)

Nielsen, Peter Vilhelm

The main task of the ventilation system or the air-conditioning system is to supply· and remove air and airborne materials and to supply or remove heat from a room. The necessary level of fresh air will be supplied to· a room by a ventilation system, and heat from equipment or solar radiation can...... be removed by an air-conditioning system. An industrial ventilation system may both take care of the occupants' comfort and the industrial processes in the area....

Technology Solutions Case Study: Selecting Ventilation Systems for Existing Homes

Energy Technology Data Exchange (ETDEWEB)

None

2014-12-01

In multifamily buildings, particularly in the Northeast, exhaust ventilation strategies are the norm as a means of meeting both local exhaust and whole-unit mechanical ventilation rates. The issue of where the "fresh" air is coming from is gaining significance as air-tightness standards for enclosures become more stringent, and the normal leakage paths through the building envelope disappear. Researchers from the Consortium for Advanced Residential Buildings (CARB) found that the majority of high performance, new construction, multifamily housing in the Northeast use one of four general strategies for ventilation: continuous exhaust only with no designated supply or make-up air source, continuous exhaust with ducted make-up air to apartments, continuous exhaust with supply through a make-up air device integral to the unit HVAC, and continuous exhaust with supply through a passive inlet device, such as a trickle vent. Insufficient information is available to designers on how these various systems are best applied. In this project, the CARB team evaluated the four different strategies for providing make-up air to multifamily residential buildings and developed guidelines to help contractors and building owners choose the best ventilation systems.

[Anesthesia ventilators].

Science.gov (United States)

Otteni, J C; Beydon, L; Cazalaà, J B; Feiss, P; Nivoche, Y

1997-01-01

To review anaesthesia ventilators in current use in France by categories of ventilators. References were obtained from computerized bibliographic search. (Medline), recent review articles, the library of the service and personal files. Anaesthesia ventilators can be allocated into three groups, depending on whether they readminister expired gases or not or allow both modalities. Contemporary ventilators provide either constant volume ventilation, or constant pressure ventilation, with or without a pressure plateau. Ventilators readministering expired gases after CO2 absorption, or closed circuit ventilators, are either of a double- or a single-circuit design. Double-circuit ventilators, or pneumatical bag or bellows squeezers, or bag-in-bottle or bellows-in-bottle (or box) ventilators, consist of a primary, or driving circuit (bottle or box) and a secondary or patient circuit (including a bag or a bellows or membrane chambers). Bellows-in-bottle ventilators have either standing bellows ascending at expiration, or hanging bellows, descending at expiration. Ascending bellows require a positive pressure of about 2 cmH2O throughout exhalation to allow the bellows to refill. The expired gas volume is a valuable indicator for leak and disconnection. Descending bellows generate a slight negative pressure during exhalation. In case of leak or disconnection they aspirate ambient air and cannot act therefore as an indicator for integrity of the circuit and the patient connection. Closed circuit ventilators with a single-circuit (patient circuit) include a insufflating device consisting either in a bellows or a cylinder with a piston, operated by a electric or pneumatic motor. As the hanging bellows of the double circuit ventilators, they generate a slight negative pressure during exhalation and aspirate ambient air in case of leak or disconnection. Ventilators not designed for the readministration of expired gases, or open circuit ventilators, are generally stand

Measuring Air Temperature in Glazed Ventilated Facades in the Presence of Direct Solar Radiation

DEFF Research Database (Denmark)

Kalyanova, Olena; Zanghirella, Fabio; Heiselberg, Per

2007-01-01

A distinctive element of buildings with a double glazed façade is naturally or mechanically driven flow in a ventilated cavity. Accurate air temperature measurements in the cavity are crucial to evaluate the dynamic performance of the façade, to predict and control its behavior as a significant...... part of the complete ventilation system. Assessment of necessary cooling/heating loads and of the whole building energy performance will then depend on the accuracy of measured air temperature. The presence of direct solar radiation is an essential element for the façade operation, but it can heavily...... affect measurements of air temperature and may lead to errors of high magnitude using bare thermocouples and even adopting shielding devices. Two different research groups, from Aalborg University and Politecnico di Torino, tested separately various techniques to shield thermocouples from direct...

Impact of ventilation rates on SBS symptoms and productivity in offices

DEFF Research Database (Denmark)

Wargocki, Pawel; Fanger, Povl Ole

1999-01-01

Perceived air quality, Sick Building Syndrome (SBS) symptoms and productivity were studied in a normally furnished office space ventilated with an outdoor air flow of 3, 10 and 30 L/s per person (corresponding to aiur changes of 0.6, 2.0 and 6 h-1, respectively), while all other environmental...... subjects occupied the office for 4.6 hours in the afternoon, six subjects at a time; they remained thermally neutral by adjusting their clothing. Subjects assessed perceived air quality and SBS symptoms, and performed simulated office work so that their productivity could be assessed. Increasing the supply...

Review of low-energy construction, air tightness, ventilation strategies and indoor radon: results from Finnish houses and apartments

International Nuclear Information System (INIS)

Arvela, H.; Holmgren, O.; Reisbacka, H.; Vinha, J.

2014-01-01

Low-energy and passive house construction practices are characterised by increased insulation, high air tightness of the building shell and controlled mechanical ventilation with heat recovery. As a result of the interaction of mechanical ventilation and high air tightness, the pressure difference in a building can be markedly enhanced. This may lead to elevated indoor radon levels. Minor leakages in the foundation can affect the radon concentration, even in the case where such leaks do not markedly reduce the total air tightness. The potential for high pressures to affect indoor radon concentrations markedly increases when the air tightness ACH 50 , i.e. the air change per hour induced by a pressure difference of 50 Pa, is -1 . Pressure differences in Finnish low-rise residential houses having mechanical supply and exhaust ventilation with heat recovery (MSEV) are typically 2-3 Pa, clearly lower than the values of 5-9 Pa in houses with only mechanical exhaust ventilation (MEV). In MSEV houses, radon concentrations are typically 30 % lower than in MEV houses. In new MSEV houses with an ACH50 of 0.6 h -1 , the limit for passive construction, the analytical estimates predict an increase of 100 % in the radon concentration compared with older houses with an ACH50 of 4.0 h -1 . This poses a challenge for efficient radon prevention in new construction. Radon concentrations are typically 30 % lower in houses with two storeys compared with only one storey. The introduction of an MSEV ventilation strategy in typically very airtight apartments has markedly reduced pressure differences and radon concentrations. (authors)

Operational experience of air washer based ventilation system for power conditioning system of Indus-2

International Nuclear Information System (INIS)

Pandey, R.M.; Baghel, S.L.; Parate, J.K.; Ahlawat, Sandeep; Rawlani, B.K.; Chouksey, Sanjay

2015-01-01

Indus-2 Synchrotron Accelerator requires high quality conditioned uninterrupted AC mains power for their smooth and reliable operation. Three units of 1670 kVA and one unit of 1100 kVA capacity rotary uninterruptible power conditioning systems (UPS) were installed and commissioned. These UPS units require dust free and cool ambient conditions for smooth operation. In order to meet the ventilation requirements, an evaporative cooling system of 80000 cubic meter/hour capacity with filtration units was designed, installed and commissioned in February 2011 and is operational on round-the-clock basis. Evaporative cooling scheme was chosen as has various advantages over a refrigerated system like lower initial capital costs, lower energy usage, lower running costs, less greenhouse gas and it does not contribute to ozone depletion. The ventilation system filters the environment air in stages up to 5 micron level and being conditioned with an automatic controlled soft water circulating system with cooling pads. An instrumentation and control scheme is included in the system to provide the automation requirements for operating 24 x 7 through the year. All the mechanical, hydraulic and electrical devices are maintained by providing preventive maintenance work without affecting the accelerator machine operation. Availability and reliability of the system was analysed based on the failure data. In Year 2014, the ventilation system was upgraded to accommodate standby blower unit, coupling unit and improved quality of supply air with new air conditioning devices. The control panel monitors the condition of air in the UPS hall and maintainsup to 28°C air temperature and 85% maximum relative humidity in round-the clock shift with more than 98% operational reliability. In this paper, we present design philosophy, installation, instrumentation, testing, operation experience and availability of the ventilation system for Power Conditioning System, Indus complex. (author)

Ventilation, temperature, and HVAC characteristics in small and medium commercial buildings in California.

Science.gov (United States)

Bennett, D H; Fisk, W; Apte, M G; Wu, X; Trout, A; Faulkner, D; Sullivan, D

2012-08-01

This field study of 37 small and medium commercial buildings throughout California obtained information on ventilation rate, temperature, and heating, ventilating, and air-conditioning (HVAC) system characteristics. The study included seven retail establishments; five restaurants; eight offices; two each of gas stations, hair salons, healthcare facilities, grocery stores, dental offices, and fitness centers; and five other buildings. Fourteen (38%) of the buildings either could not or did not provide outdoor air through the HVAC system. The air exchange rate averaged 1.6 (s.d. = 1.7) exchanges per hour and was similar between buildings with and without outdoor air supplied through the HVAC system, indicating that some buildings have significant leakage or ventilation through open windows and doors. Not all buildings had sufficient air exchange to meet ASHRAE 62.1 Standards, including buildings used for fitness centers, hair salons, offices, and retail establishments. The majority of the time, buildings were within the ASHRAE temperature comfort range. Offices were frequently overcooled in the summer. All of the buildings had filters, but over half the buildings had a filter with a minimum efficiency reporting value rating of 4 or lower, which are not very effective for removing fine particles. Most U.S. commercial buildings (96%) are small- to medium-sized, using nearly 18% of the country's energy, and sheltering a large population daily. Little is known about the ventilation systems in these buildings. This study found a wide variety of ventilation conditions, with many buildings failing to meet relevant ventilation standards. Regulators may want to consider implementing more complete building inspections at commissioning and point of sale. © 2012 John Wiley & Sons A/S.

The effect of using low-polluting building materials on ventilation requirements and energy use in buildings

Energy Technology Data Exchange (ETDEWEB)

Wargocki, P.; Frontczak, M. (International Centre for Indoor Environment and Energy, Dept. of Mechanical Engineering, DTU, Kgs. Lyngby (DK)); Knudsen, Henrik N. (Danish Building Research Institute, Aalborg Univ., Hoersholm (DK))

2007-07-01

The main objective of the ongoing research project described in this paper was to study the potential for reducing energy used for ventilating buildings by using low-polluting building materials, without compromising the indoor air quality. To quantify this potential, the exposure-response relationships, i.e. the relationships between ventilation rate and perceived indoor air quality, were established for rooms furnished with different categories of polluting materials and the simulations of energy used for ventilation were carried out. The exposure-response relationships were based on a summary of data reported in the literature on exposure-response relationships for materials tested in laboratory settings in small-scale glass chambers, and in full-scale in climate chambers, test rooms or normal offices. New experiments were also considered in which the effect of using low-polluting materials on perceived air quality was examined in test rooms ventilated with different outdoor air supply rates, low-polluting materials being selected in small glass chambers. The results suggest that the exposure-response relationships vary between different building materials and that the perceived air quality can be improved considerably when polluting building materials are substituted with materials that pollute less. The preliminary energy simulations indicate that selecting low-polluting materials will result in considerable energy savings as a result of reducing the ventilation rates required to achieve acceptable indoor air quality. (au)

Energy efficient biological air cleaning for farm stable ventilation; Energieffektiv biologisk luftrensning til staldventilation

Energy Technology Data Exchange (ETDEWEB)

Groenborg Nicolaisen, C.; Hansen, Mads P.R. [Teknologisk Institut, Aarhus (Denmark); Stroem, J.; Soerensen, Keld [DXT. Danish Exergy Technology A/S, Skoerping (Denmark); Goetke, C. [Lokalenergi Aarhus, Viby J. (Denmark); Morsing, S.; Soerensen, Lars C. [SKOV A/S, Roslev (Denmark); Ladegaerd Jensen, T.; Pedersen, Poul [Videncenter for svineproduktion, Copenhagen (Denmark)

2013-05-01

The project has been designed to reduce energy consumption for air purification by 30% while having a payback period of maximum 3 years. The project has achieved very significant results which are far above the target. Particularly satisfying is the wide range of new components that are launched in late 2012. By implementing the newly developed system at 100% cleaning (LPC 13 ventilators and Dynamic multistep control) in relation to Best Practice (SKOV's original system with DA600 fans) in a concrete pigsty, a saving of 61% and a simple payback of 1.7 years is achieved. Similarly, it is found that the energy used for pump operation can be reduced by 37% with the new Dynamic sprinkling control. At 20% cleaning a potential saving of 15% per year and a payback period of between 0 and 5 years was found, which is dependent on the desired performance as the capacities in the bio-filter's upper capacity range between 26 thousand to 30 thousand m3 / h entails costs for an additional extraction unit in the new solution. Furthermore, the newly developed components proved highly suitable for standard installations without air cleaning where a savings potential is 53% and the payback period 1.5 years. Product-wise, the project formed the basis for the development of: 1. New energy-efficient ventilation units (LPC11, 12,13) that are suitable for air purification; 2. A new energy-saving control principle (Dynamic Multi-Step) which is particularly suitable for low-energy ventilators; 3. A new energy-saving flow measurement system for ventilating ducts (Dynamic air to the central exhaust); 4. An energy-saving pressure control in common ducts (pressure control as a function of outside temperature); 5. Proposal for a new energy-saving pump operation for sprinkling of biological filters (Dynamic sprinkling). (LN)

[Disinfectants and main sanitary and preventive measures for protection of ventilation and air-conditioning systems from Legionella contamination].

Science.gov (United States)

Gerasimov, V N; Golov, E A; Khramov, M V; Diatlov, I A

2008-01-01

The study was devoted to selection and assessment of disinfecting preparations for prevention of contamination by Legionella. Using system of criteria for quality assessment of disinfectants, seven newdomestic ones belonging to quaternary ammonium compounds class or to oxygen-containing preparations and designed for disinfecting of air-conditioning and ventilation systems were selected. Antibacterial and disinfecting activities of working solutions of disinfectants were tested in laboratory on the test-surfaces and test-objects of premises' air-conditioning and ventilation systems contaminated with Legionella. High antimicrobial and disinfecting activity of new preparations "Dezactiv-M", "ExtraDez", "Emital-Garant", "Aquasept Plus", "Samarovka", "Freesept", and "Ecobreeze Oxy" during their exposure on objects and materials contaminated with Legionella was shown. Main sanitary and preventive measures for defending of air-conditioning and ventilation systems from contamination by Legionella species were presented.

Effectiveness of heating, ventilation and air conditioning system with HEPA filter unit on indoor air quality and asthmatic children's health

Energy Technology Data Exchange (ETDEWEB)

Xu, Ying; Raja, Suresh; Ferro, Andrea R.; Jaques, Peter A.; Hopke, Philip K. [Clarkson University, 8 Clarkson Avenue, Center for Air Resources Engineering and Science, Potsdam, NY 13699 (United States); Gressani, Cheryl; Wetzel, Larry E. [Air Innovations, Inc, 7000 Performance Drive, North Syracuse, NY 13212 (United States)

2010-02-15

Poor indoor air quality has been linked to the exacerbation of asthma symptoms in children. Because people spend most of their time indoors, improving indoor air quality may provide some relief to asthma sufferers. A study was conducted to assess whether operating an air cleaning/ventilating unit (HEPAiRx {sup registered}) in a child's bedroom can improve his/her respiratory health. Thirty children diagnosed with asthma were randomly split into two groups. For the first six weeks, group A had the air cleaning/ventilating unit (HEPAiRx {sup registered}) running in the bedrooms of the participants and group B did not; for the second six weeks, both groups had the cleaners running in the bedrooms; and, for the final six weeks, group A turned the cleaners off and group B kept theirs running. Indoor air quality parameters, including temperature, relative humidity, particulate matter (PM 0.5-10 {mu}m), carbon monoxide, carbon dioxide and total volatile organic compound (TVOC) concentrations, were monitored in each bedroom using an AirAdvice indoor air quality multi-meter. As a measure of pulmonary inflammation, exhaled breath condensate (EBC) was collected every sixth day and analyzed for nitrate and pH. Peak expiratory flow (PEF) was also measured. PM and TVOC concentrations decreased with operation of the HEPAiRx an average of 72% and 59%, respectively. The EBC nitrate concentrations decreased significantly and the EBC pH and PEF values increased significantly with operation of the unit (p < 0.001 when comparing on/off sample means). These results indicate that air cleaning in combination with ventilation can effectively reduce symptoms for asthma sufferers. (author)

Adaptive support ventilation may deliver unwanted respiratory rate-tidal volume combinations in patients with acute lung injury ventilated according to an open lung concept.

Science.gov (United States)

Dongelmans, Dave A; Paulus, Frederique; Veelo, Denise P; Binnekade, Jan M; Vroom, Margreeth B; Schultz, Marcus J

2011-05-01

With adaptive support ventilation, respiratory rate and tidal volume (V(T)) are a function of the Otis least work of breathing formula. We hypothesized that adaptive support ventilation in an open lung ventilator strategy would deliver higher V(T)s to patients with acute lung injury. Patients with acute lung injury were ventilated according to a local guideline advising the use of lower V(T) (6-8 ml/kg predicted body weight), high concentrations of positive end-expiratory pressure, and recruitment maneuvers. Ventilation parameters were recorded when the ventilator was switched to adaptive support ventilation, and after recruitment maneuvers. If V(T) increased more than 8 ml/kg predicted body weight, airway pressure was limited to correct for the rise of V(T). Ten patients with a mean (±SD) Pao(2)/Fio(2) of 171 ± 86 mmHg were included. After a switch from pressure-controlled ventilation to adaptive support ventilation, respiratory rate declined (from 31 ± 5 to 21 ± 6 breaths/min; difference = 10 breaths/min, 95% CI 3-17 breaths/min, P = 0.008) and V(T) increased (from 6.5 ± 0.8 to 9.0 ± 1.6 ml/kg predicted body weight; difference = 2.5 ml, 95% CI 0.4-4.6 ml/kg predicted body weight, P = 0.02). Pressure limitation corrected for the rise of V(T), but minute ventilation declined, forcing the user to switch back to pressure-controlled ventilation. Adaptive support ventilation, compared with pressure-controlled ventilation in an open lung strategy setting, delivers a lower respiratory rate-higher V(T) combination. Pressure limitation does correct for the rise of V(T), but leads to a decline in minute ventilation.

Research review: Indoor air quality control techniques

International Nuclear Information System (INIS)

Fisk, W.J.

1986-10-01

Techniques for controlling the concentration of radon, formaldehyde, and combustion products in the indoor air are reviewed. The most effective techniques, which are generally based on limiting or reducing indoor pollutant source strengths, can decrease indoor pollutant concentrations by a factor of 3 to 10. Unless the initial ventilation rate is unusually low, it is difficult to reduce indoor pollutant concentrations more than approximately 50% by increasing the ventilation rate of an entire building. However, the efficiency of indoor pollutant control by ventilation can be enhanced through the use of local exhaust ventilation near concentrated sources of pollutants, by minimizing short circuiting of air from supply to exhaust when pollutant sources are dispersed and, in some situations, by promoting a displacement flow of air and pollutants toward the exhaust. Active air cleaning is also examined briefly. Filtration and electrostatic air cleaning for removal of particles from the indoor air are the most practical and effective currently available techniques of air cleaning. 49 refs., 7 figs

EVALUATION TOOL OF CLIMATE POTENTIAL FOR VENTILATIVE COOLING

DEFF Research Database (Denmark)

Belleri, Annamaria; Psomas, Theofanis Ch.; Heiselberg, Per Kvols

2015-01-01

. Within IEA Annex 62 project, national experts are working on the development of a climate evaluation tool, which aims at assessing the potential of ventilative cooling by taking into account also building envelope thermal properties, internal gains and ventilation needs. The analysis is based on a single......-zone thermal model applied to user-input climatic data on hourly basis. The tool identifies the percentage of hours when natural ventilation can be exploited to assure minimum air change rates required by state of the art research, standards and regulations and the percentage of hours when direct ventilative...

Building ventilation, state of the art, prospective

International Nuclear Information System (INIS)

1995-10-01

This conference is composed of 21 communications and 21 posters in the domain of building ventilation and indoor air quality; the main themes are: indoor air quality assessment and optimization; performance enhancement and optimization of ventilation systems and equipment; ventilation systems for renovated and rehabilitated buildings; French and European regulations, standardizations and certifications; experimental and numerical simulation studies concerning ventilation systems, air flow, temperature distribution, air quality, radon decontamination, thermal comfort and acoustic levels in buildings

Performance analysis of a new design of office diffuse ceiling ventilation system

DEFF Research Database (Denmark)

Fan, Jianhua; Hviid, Christian Anker; Yang, Honglu

2013-01-01

This paper aims to document and analyse performance of a new design of diffuse ceiling ventilation system in a typical office room. A full scale measurement is carried out in a climate chamber with an office setup at the Technical University of Denmark. Indoor air temperatures, air speeds, wall...... surface temperatures, pressure loss of the ceiling and ventilation effectiveness are measured for an air change rate of 3.5 h-1 and 5.1 h -1 respectively. A computational fluid dynamics model of the office with the diffuse ceiling ventilation system is built and validated by the full scale measurement....... The measurements of pressure loss across the ceiling show a low pressure drop between the plenum and the occupied zone. Ventilation effectiveness is measured to be close to 1 on average under the tested conditions. It is shown that the diffuse ceiling ventilation system is able to remove indoor pollutant...

Increasing ventilation as an intervention in homes of asthmatic children

DEFF Research Database (Denmark)

Hogaard, Nina Viskum; Rubak, Sune Leisgaard Mørck; Halken, Susanne

2016-01-01

in children. We conducted a double-blind, placebo-controlled intervention study with 46 asthmatic, house dust mite allergic children. The aim was to investigate the association between indoor air quality in homes and severity of asthma, in particular the effect of increased ventilation rate and expected lower...... exposure to HDM on medication intake among these children. As a result of the intervention, the ventilation rate increased and the CO2 concentration fell significantly compared to baseline in the intervention group. The analyses of the effect of ventilation on health outcomes are being processed...

Ventilation filters as sources of air pollution – Processes occurring on surfaces of used filters

DEFF Research Database (Denmark)

Bekö, Gabriel; Halás, Oto; Clausen, Geo

2004-01-01

Ozone concentrations were monitored upstream and downstream of used filter samples following 24hours of ventilation with ozone- filtered air. The ozone concentration in the air upstream of the filters was maintained at ~75 ppb while the concentration downstream of the filters was initially betwee...

Optimization of air-curtain sealing efficiency with respect to heat transfer in naturally ventilated buildings

NARCIS (Netherlands)

Khayrullina, A.; Hooff, van T.A.J.; Blocken, B.J.E.; van Heijst, G.J.F.; Sun, Y.; Pei, J.; Zhao, X

This study presents results of coupled 3D steady Reynolds-averaged Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) simulations of an isolated naturally-ventilated building with the application of an air curtain to prevent heat transfer across a doorway. The considered parameters include air

Association between ventilation rates in 390 Swedish homes and allergic symptoms in children

DEFF Research Database (Denmark)

Bornehag, Carl Gustaf; Sundell, Jan; Hagerhed-Engman, L.

2005-01-01

in 390 homes, were examined by physicians. Ventilation rates were measured by a passive tracer gas method, and inspections were carried out in the homes. About 60% of the multi-family houses and about 80% of the single-family houses did not fulfill the minimum requirement regarding ventilation rate...

Why We Ventilate

Energy Technology Data Exchange (ETDEWEB)

Logue, Jennifer M.; Sherman, Max H.; Price, Phil N.; Singer, Brett C.

2011-09-01

It is widely accepted that ventilation is critical for providing good indoor air quality (IAQ) in homes. However, the definition of"good" IAQ, and the most effective, energy efficient methods for delivering it are still matters of research and debate. This paper presents the results of work done at the Lawrence Berkeley National Lab to identify the air pollutants that drive the need for ventilation as part of a larger effort to develop a health-based ventilation standard. First, we present results of a hazard analysis that identified the pollutants that most commonly reach concentrations in homes that exceed health-based standards or guidelines for chronic or acute exposures. Second, we present results of an impact assessment that identified the air pollutants that cause the most harm to the U.S. population from chronic inhalation in residences. Lastly, we describe the implications of our findings for developing effective ventilation standards.

Experimental Investigation of Flow Resistance in a Coal Mine Ventilation Air Methane Preheated Catalytic Oxidation Reactor

OpenAIRE

Zheng, Bin; Liu, Yongqi; Liu, Ruixiang; Meng, Jian; Mao, Mingming

2015-01-01

This paper reports the results of experimental investigation of flow resistance in a coal mine ventilation air methane preheated catalytic oxidation reactor. The experimental system was installed at the Energy Research Institute of Shandong University of Technology. The system has been used to investigate the effects of flow rate (200 Nm3/h to 1000 Nm3/h) and catalytic oxidation bed average temperature (20°C to 560°C) within the preheated catalytic oxidation reactor. The pressure drop and res...

Evidence of inadequate ventilation in portable classrooms: results of a pilot study in Los Angeles County.

Science.gov (United States)

Shendell, D G; Winer, A M; Weker, R; Colome, S D

2004-06-01

The prevalence of prefabricated, portable classrooms (portables) for United States public schools has increased; in California, approximately one of three students learn inside portables. Limited research has been conducted on indoor air and environmental quality in American schools, and almost none in portables. Available reports and conference proceedings suggest problems from insufficient ventilation due to poor design, operation, and/or maintenance of heating, ventilation and air conditioning (HVAC) systems; most portables have one mechanical, wall-mounted HVAC system. A pilot assessment was conducted in Los Angeles County, including measurements of integrated ventilation rates based on a perfluorocarbon tracer gas technique and continuous monitoring of temperature (T) and relative humidity (RH). Measured ventilation rates were low [mean school day integrated average 0.8 per hour (range: 0.1-2.9 per hour)]. Compared with relevant standards, results suggested adequate ventilation and associated conditioning of indoor air for occupant comfort were not always provided to these classrooms. Future school studies should include integrated and continuous measurements of T, RH, and ventilation with appropriate tracer gas methods, and other airflow measures. Adequate ventilation has the potential to mitigate concentrations of chemical pollutants, particles, carbon dioxide, and odors in portable and traditional classrooms, which should lead to a reduction in reported health outcomes, e.g., symptoms of 'sick building syndrome', allergies, asthma. Investigations of school indoor air and environmental quality should include continuous temperature and relative humidity data with inexpensive instrumentation as indicators of thermal comfort, and techniques to measure ventilation rates.

Ionization detector for aerosol air pollution detection and ventilation control in the metal processing industry

International Nuclear Information System (INIS)

Kovacs, Istvan

1989-01-01

An indicator and measuring instrument was developed for the continuous monitoring, recording and indicating aerosol mass concentrations in mechanical workshops, like in metal cutting, welding or forming industries, for air pollution control and ventilation of the atmosphere in the workshops. An ionization chamber containing alpha radiation source was modified for this purpose, and a suitable electronic circuit was built for the measurement of ionization current. The calibration of the ionization aerosol detectors was performed for welding smoke and oil mist. They were suitable for continuous monitoring of workshop atmospheres and controlling ventilation equipment, or as portable instruments, for the rapid inspection of air pollution. (R.P.) 4 refs.; 3 figs

Dispersal of Exhaled Air and Personal Exposure in Displacement Ventilated Rooms

DEFF Research Database (Denmark)

Bjørn, Erik; Nielsen, Peter Vilhelm

2002-01-01

The influence of the human exhalation on flow fields, contaminant distributions, and personal exposures in displacement ventilated rooms is studied together with the effects of physical movement. Experiments are conducted in full-scale test rooms with life-sized breathing thermal manikins....... Numerical simulations support the experiments. Air exhaled through the mouth can lock in a thermally stratified layer, if the vertical temperature gradient in breathing zone height is sufficiently large. With exhalation through the nose, exhaled air flows to the upper part of the room. The exhalation flow...

An air flow sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique.

Science.gov (United States)

Battista, L; Sciuto, S A; Scorza, A

2013-03-01

In this work, a simple and low-cost air flow sensor, based on a novel fiber-optic sensing technique has been developed for monitoring air flows rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of air flow acting on it; the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an air flow sensor suitable for the measurement of air flow rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the air flow sensor is here proposed and a static calibration of two different arrangements has been performed: a measurement range up to 3.00 × 10(-4) m(3)∕s (18.0 l∕min) for the mono-directional sensor and a measurement range of ±3.00 × 10(-4) m(3)∕s (±18.0 l∕min) for the bi-directional sensor are experimentally evaluated, according to the air flow rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed theoretical model: for the mono

Particle deposition in ventilation ducts

Energy Technology Data Exchange (ETDEWEB)

Sippola, Mark Raymond [Univ. of California, Berkeley, CA (United States)

2002-09-01

Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation. Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling. Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 μm were investigated. Deposition rates were measured in straight ducts with a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence. Measured deposition rates were generally higher than predicted by published models. A model incorporating empirical equations based on the

Numerical Simulation of Inter-Flat Air Cross-Contamination under the Condition of Single-Sided Natural Ventilation

DEFF Research Database (Denmark)

Liu, Xiaoping; Niu, Jianlei; Perino, Marco

2008-01-01

ventilated room, the renormalization group based k-ε model, together with carbon dioxide used as a tracer, is chosen to reveal this air cross-contamination. The simulation results are in agreement with our prior on-site tracer-gas measurements, revealing that the windows flush with a flat fa ade can...... be a major route of the air cross-contamination in high-rise residential buildings. Finally, an assessment index is proposed to evaluate the potential infection risks associated with this inter-flat air flow occurring in high-rise residential buildings....... the two sides, each of which has a flat fa ade with openable windows. When the wind speed is extremely low, with doors closed and windows opened, the flats become single-sided naturally ventilated driven by buoyancy effects. The air pollutants can travel from a lower flat to a vertically adjacent upper...

Evaluation of an Incremental Ventilation Energy Model for Estimating Impacts of Air Sealing and Mechanical Ventilation

Energy Technology Data Exchange (ETDEWEB)

Logue, Jennifer M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Turner, Willliam JN [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Walker, Iain S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Singer, Brett C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2012-07-01

Changing the rate of airflow through a home affects the annual thermal conditioning energy. Large-scale changes to airflow rates of the housing stock can significantly alter the energy consumption of the residential energy sector. However, the complexity of existing residential energy models hampers the ability to estimate the impact of policy changes on a state or nationwide level. The Incremental Ventilation Energy (IVE) model developed in this study was designed to combine the output of simple airflow models and a limited set of home characteristics to estimate the associated change in energy demand of homes. The IVE model was designed specifically to enable modelers to use existing databases of home characteristics to determine the impact of policy on ventilation at a population scale. In this report, we describe the IVE model and demonstrate that its estimates of energy change are comparable to the estimates of a wellvalidated, complex residential energy model when applied to homes with limited parameterization. Homes with extensive parameterization would be more accurately characterized by complex residential energy models. The demonstration included a range of home types, climates, and ventilation systems that cover a large fraction of the residential housing sector.

Induced radioactivity in air-estimation of ventilation rates at the vault and experimental areas of the proposed K-500 superconducting cyclotron, Calcutta

International Nuclear Information System (INIS)

Ravishankar, R.

1999-01-01

Guidelines are given for the necessary ventilation rates in vault and experimental areas from radiological safety point of view, for the proposed K-500 super-conducting cyclotron at Calcutta. A method is presented for estimating the amount of short lived radioisotopes like 13 N and 15 O taking the (n,2n) mode of productions. Considering the operating conditions of K-500 machine for the production of maximum neutron flux (300 MeV, 50pnA Li beam on Ta target) the energy differential neutron flux and the energy differential production cross section of 13 N and 15 O have been generated using ALICE-91 computer code. The differential cross sections have been folded with radial neutron flux distribution and then integrated over the entire volume of the cyclotron vault, to obtain the total production of the two radioactive gases. The DAC values have been obtained by considering the immersion dose in a semi-infinite hemispherical cloud. Natural decay and removal due to ventilation have been considered to get the recommended ventilation rates. (author)

Test Plan for Measuring Ventilation Rates and Combustible Gas Levels in TWRS Active Catch Tanks

Energy Technology Data Exchange (ETDEWEB)

NGUYEN, D.M.

1999-10-25

The purpose of this sampling activity is to obtain data to support an initial evaluation of potential hazards due to the presence of combustible gas in catch tanks that are currently operated by the River Protection Project (RPP). Results of the hazard analysis will be used to support closure of the flammable gas unreviewed safety question for these facilities. The data collection will be conducted in accordance with the Tank Safety Screening Data Quality Objective (Dukelow et al. 1995). Combustible gas, ammonia, and organic vapor levels in the headspace of the catch tanks will be field-measured using hand-held instruments. If a combustible gas level measurement in a tank exceeds an established threshold, gas samples will he collected in SUMMA' canisters for more extensive laboratory analysis. In addition, ventilation rates of some catch tanks will be measured to evaluate removal of flammable gas by air flowing through the tanks. This test plan identifies the sample collection, laboratory analysis, quality assurance, and reporting objectives for this data collection effort. The plan also provides the procedures for field measurement of combustible gas concentrations and ventilation rates.

Can a photocatalytic air purifier be used to improve the perceived air quality indoors?

DEFF Research Database (Denmark)

Kolarik, Jakub; Wargocki, Pawel

2010-01-01

The effect of a photocatalytic air purifier on perceived air quality(PAQ) was examined in rooms polluted by typical sources of indoor pollution.The rooms were ventilated at three different outdoor air supply rates. The air quality was assessed by a sensory panel when the purifier was in operation...... as well as when it was off. Operation of the purifier significantly improved PAQ in the rooms polluted by building materials (used carpet, old linoleum, and old chip-board), and a used ventilation filter as well as a mixture of building materials, used ventilation filter and cathode-ray tube computer...... monitors. The effect cor-responded to approximately doubling the outdoor air supply rate. Operation of the purifier significantly worsened the PAQ in rooms with human bioeffluents, probably due to incomplete oxidation of alcohols which are one of the main pollutants emitted by humans. Present results show...

An innovation wall model based on interlayer ventilation

International Nuclear Information System (INIS)

Feng Jinmei; Lian Zhiwei; Hou Zhijian

2008-01-01

The thermal characteristics of the external wall are important to the energy consumption of the air conditioning system. Great attention should also be paid to the energy loss of the air exhaust. An innovation wall model based on interlayer ventilation is presented in this paper. The interlayer ventilation wall combines the wall and air exhaust of heating, ventilating and air conditioning (HVAC). The results of the experiment show that the energy loss of the exhaust air can be fully recovered by the interlayer ventilation wall. The cooling load can be reduced greatly because the temperature difference between the internal surface of the interlayer ventilation wall and the indoor air is very small. Clearly, the small temperature difference can enhance thermal comfort. In order to popularize the interlayer ventilation wall, technical and economical analysis is presented in this paper. Based on the buildings in the Shanghai area and a standard air conditioning system, a 4 years payback period for interlayer ventilation wall implementation was found according to the analysis

Characterization of natural ventilation in wastewater collection systems.

Science.gov (United States)

Ward, Matthew; Corsi, Richard; Morton, Robert; Knapp, Tom; Apgar, Dirk; Quigley, Chris; Easter, Chris; Witherspoon, Jay; Pramanik, Amit; Parker, Wayne

2011-03-01

The purpose of the study was to characterize natural ventilation in full-scale gravity collection system components while measuring other parameters related to ventilation. Experiments were completed at four different locations in the wastewater collection systems of Los Angeles County Sanitation Districts, Los Angeles, California, and the King County Wastewater Treatment District, Seattle, Washington. The subject components were concrete gravity pipes ranging in diameter from 0.8 to 2.4 m (33 to 96 in.). Air velocity was measured in each pipe using a carbon-monoxide pulse tracer method. Air velocity was measured entering or exiting the components at vents using a standpipe and hotwire anemometer arrangement. Ambient wind speed, temperature, and relative humidity; headspace temperature and relative humidity; and wastewater flow and temperature were measured. The field experiments resulted in a large database of measured ventilation and related parameters characterizing ventilation in full-scale gravity sewers. Measured ventilation rates ranged from 23 to 840 L/s. The experimental data was used to evaluate existing ventilation models. Three models that were based upon empirical extrapolation, computational fluid dynamics, and thermodynamics, respectively, were evaluated based on predictive accuracy compared to the measured data. Strengths and weaknesses in each model were found and these observations were used to propose a concept for an improved ventilation model.

Parameter study on performance of building cooling by night-time ventilation

DEFF Research Database (Denmark)

Artmann, Nikolai; Manz, H.; Heiselberg, Per

2008-01-01

of different parameters such as building construction, heat gains, air change rates, heat transfer coefficients and climatic conditions including annual variations on the number of overheating degree hours (operative room temperature >26 °C) was evaluated. Climatic conditions and air flow rate during night......Especially for commercial buildings in moderate climates, night-time ventilation seems to be a simple and energy-efficient approach to improve thermal comfort in summer. However, due to uncertainties in the prediction of thermal comfort in buildings with night-time ventilation, architects...... and engineers are still hesitant to apply this technique. In order to reduce the uncertainties, the most important parameters affecting night ventilation performance need to be identified. A typical office room was therefore modelled using a building energy simulation programme (HELIOS), and the effect...

Experimental study of airflow characteristics of stratum ventilation in a multi-occupant room with comparison to mixing ventilation and displacement ventilation.

Science.gov (United States)

Cheng, Y; Lin, Z

2015-12-01

The motivation of this study is stimulated by a lack of knowledge about the difference of airflow characteristics between a novel air distribution method [i.e., stratum ventilation (SV)] and conventional air distribution methods [i.e., mixing ventilation (MV) and displacement ventilation (DV)]. Detailed air velocity and temperature measurements were conducted in the occupied zone of a classroom with dimensions of 8.8 m (L) × 6.1 m (W) × 2.4 m (H). Turbulence intensity and power spectrum of velocity fluctuation were calculated using the measured data. Thermal comfort and cooling efficiency were also compared. The results show that in the occupied zone, the airflow characteristics among MV, DV, and SV are different. The turbulent airflow fluctuation is enhanced in this classroom with multiple thermal manikins due to thermal buoyancy and airflow mixing effect. Thermal comfort evaluations indicate that in comparison with MV and DV, a higher supply air temperature should be adopted for SV to achieve general thermal comfort with low draft risk. Comparison of the mean air temperatures in the occupied zone reveals that SV is of highest cooling efficiency, followed by DV and then MV. This study reports the unique profiles of flow, temperature, turbulence intensity, and power spectrum of stratum ventilation, which can have a number of implications for both knowledge and understanding of the flow characteristics in a stratum-ventilated room. With respect to the former, it expounds the fundamental characteristics of this air distribution method; and with respect to the latter, it reveals the mechanism of thermal comfort and energy saving under stratum ventilation. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Thermal comfort and IAQ assessment of under-floor air distribution system integrated with personalized ventilation in hot and humid climate

DEFF Research Database (Denmark)

Li, Ruixin; Sekhar, S.C.; Melikov, Arsen Krikor

2010-01-01

The potential for improving occupants' thermal comfort with personalized ventilation (PV) system combined with under-floor air distribution (UFAD) system was explored through human response study. The hypothesis was that cold draught at feet can be reduced when relatively warm air is supplied...... of the results obtained reveal improved acceptability of perceived air quality and improved thermal sensation with PV-UFAD in comparison with the reference case of UFAD alone or mixing ventilation with ceiling supply diffuser. The local thermal sensation at the feet was also improved when warmer UFAD supply air...

Modelling dynamics of atmosphere ventilation and industrial city’s air pollution analysis: New approach

Science.gov (United States)

Glushkov, A. V.; Khetselius, O. Yu; Agayar, E. V.; Buyadzhi, V. V.; Romanova, A. V.; Mansarliysky, V. F.

2017-10-01

We present a new effective approach to analysis and modelling the natural air ventilation in an atmosphere of the industrial city, which is based on the Arakawa-Schubert and Glushkov models, modified to calculate the current involvement of the ensemble of clouds, and advanced mathematical methods of modelling an unsteady turbulence in the urban area. For the first time the methods of a plane complex field and spectral expansion algorithms are applied to calculate the air circulation for the cloud layer arrays, penetrating into the territory of the industrial city. We have also taken into account for the mechanisms of transformation of the cloud system advection over the territory of the urban area. The results of test computing the air ventilation characteristics are presented for the Odessa city. All above cited methods and models together with the standard monitoring and management systems can be considered as a basis for comprehensive “Green City” construction technology.

Ventilation of nuclear power plants

International Nuclear Information System (INIS)

Madoyan, A.A.; Vlasik, V.F.

1984-01-01

Foundations and calculation methods of ventilation of rooms with different degree of heat and gas release with the change of operation mode of NPP main equipment, as well as problems of NPP site and adjoining area aerodynamics, have been presented. Systems of air ventilation and conditioning, cooling equipment, are considered. The main points of designing are described and determination of economic efficiency of the ventilation systems are made. Technical characteristics of the ventilators, conditioners, filters and air heaters used, are presented. Organization of adjustment, tests, operation and maintenance of the ventilation systems of NPP with RBMK and WWER-type reactors, is described

IMPACT UPON ENVIRONMENT PROTECTION DUE TO DEFECTIVELY PRODUCED AND OPERATED VENTILATION SYSTEMS IN FOOD INDUSTRY

Directory of Open Access Journals (Sweden)

Izabela Małecka

2014-10-01

Full Text Available Mechanical (air-conditioning ventilation systems and equipment in the food industry may transfer various pathogenic bacteria causing, for instance, pneumonia (Legionellosis. Microclimate parameters in manufacturing shops felt by people are affected by: human factors (health, individual temperature perception etc, and non-human factors (air physical parameters, air freshness and cleanliness etc.. Microbiological contamination of process equipment, machines and systems such as ventilation and air-conditioning equipment causes growth of pathogenic bacteria. The amount of air supplied and removed from a room depends on its use and load of odours and hazardous material. As a result of dew point formation in ventilation systems may appear the so-called air-borne condensation nuclei on which steam settles when the air gets oversaturated. The air flow rate has a material influence upon comfortable conditions in human inhabited zones. In manufacturing shops where the highest air quality is a priority, radial disinfection by means of catalytic ionization is applied. In food industry manufacturing shops of higher microbiological standard, ventilation systems based on air re-circulation should not be used.

Application of Breathing Architectural Members to the Natural Ventilation of a Passive Solar House

Directory of Open Access Journals (Sweden)

Kyung-Soon Park

2016-03-01

Full Text Available The efficient operation of a passive solar house requires an efficient ventilation system to prevent the loss of energy and provide the required ventilation rates. This paper proposes the use of “breathing architectural members” (BAMs as passive natural ventilation devices to achieve much improved ventilation and insulation performance compared to mechanical ventilation. Considering the importance of evaluating the ventilation and insulation performances of the members, we also propose numerical models for predicting the heat and air movements afforded by the members. The numerical model was validated by comparison with experimental results. The effectiveness of the BAMs was also verified by installation in houses located in an area with warm climate. For this purpose, chamber experiments were performed using samples of the BAMs, as well as numerical simulations to assess natural ventilation and heat load. The main findings of the study are as follows: (1 the one-dimensional chamber experiments confirmed the validity of the numerical models for predicting the heat and air movements afforded by the BAMs. Comparison of the experimental and calculated values for the temperature of air that flowed into the room from outside revealed a difference of less than 5%; (2 observations of the case studies in which BAMs were installed in the ceilings and exterior walls of Tokyo model houses revealed good annual ventilation and energy-saving effects. When BAMs with an opening area per unit area of A = 0.002 m2/m2 were applied to three surfaces, the required ventilation rate was 0.5 ACH (air changes per hour, and this was achieved consistently. Compared to a house with general insulation and conventional mechanical ventilation, heating load was reduced by 15.3%–40.2% depending on the BAM installation points and the differing areas of the house models.

Simplified model for a ventilated glass window under forced air flow conditions

International Nuclear Information System (INIS)

Ismail, K.A.R.; Henriquez, J.R.

2006-01-01

This paper presents a study on a ventilated window composed of two glass sheets separated by a spacing through which air is forced to flow. The proposed model is one dimensional and unsteady based upon global energy balance over the glass sheets and the flowing fluid. The external glass sheet of the cavity is subjected to variable heat flow due to the solar radiation as well as variable external ambient temperature. The exchange of radiation energy (infrared radiation) between the glass sheets is also included in the formulation. Effects of the spacing between the glass sheets, variation of the forced mass flow rate on the total heat gain and the shading coefficients are investigated. The results show that the effect of the increase of the mass flow rate is found to reduce the mean solar heat gain and the shading coefficients while the increase of the fluid entry temperature is found to deteriorate the window thermal performance

Simplified model for a ventilated glass window under forced air flow conditions

Energy Technology Data Exchange (ETDEWEB)

Ismail, K.A.R. [Depto. de Engenharia Termica e de Fluidos-FEM-UNICAMP CP: 6122 CEP 13083-970 Campinas, SP (Brazil); Henriquez, J.R. [Depto. de Eng. Mecanica-DEMEC, UFPE Av. Academico Helio Ramos, S/N CEP 50740-530, Recife, PE (Brazil)

2006-02-01

This paper presents a study on a ventilated window composed of two glass sheets separated by a spacing through which air is forced to flow. The proposed model is one dimensional and unsteady based upon global energy balance over the glass sheets and the flowing fluid. The external glass sheet of the cavity is subjected to variable heat flow due to the solar radiation as well as variable external ambient temperature. The exchange of radiation energy (infrared radiation) between the glass sheets is also included in the formulation. Effects of the spacing between the glass sheets, variation of the forced mass flow rate on the total heat gain and the shading coefficients are investigated. The results show that the effect of the increase of the mass flow rate is found to reduce the mean solar heat gain and the shading coefficients while the increase of the fluid entry temperature is found to deteriorate the window thermal performance. (author)

Control of Airborne Infectious Diseases in Ventilated Spaces

DEFF Research Database (Denmark)

Nielsen, Peter V.

2009-01-01

We protect ourselves from airborne cross-infection in the indoor environment by supplying fresh air to a room by natural or mechanical ventilation. The air is distributed in the room according to different principles: mixing ventilation, displacement ventilation, etc. A large amount of air...... to have high ventilation effectiveness. Furthermore, personalized ventilation may reduce the risk of cross-infection, and in some cases, it can also reduce the source of infection. Personalized ventilation can especially be used in hospital wards, aircraft cabins and, in general, where people are in fixed...

Ventilation in Commercial and Residential Buildings

DEFF Research Database (Denmark)

Nielsen, Peter V.

A number of areas have to be considered in connection with indoor air quality and ventilation. The selection of ventilation principle and components in the ventilation system will have influence on the indoor air quality and this subject will be discussed on the following pages. The main object o...

The transmission characteristics of indoor particles under different ventilation conditions

Directory of Open Access Journals (Sweden)

Lv Yang

2017-01-01

Full Text Available In modern society, ventilation is an important method for removing indoor particles. This study applies the parameter of attenuation index to analyze the effect of the removal of indoor particles in the two typical ventilation strategies called ceiling exhaust and slit exhaust strategy. Experiment was conducted in a chamber and riboflavin particles were used as the indoor particles source, instantaneous microbial detection (IMD used to measure the particulate concentration. Conclusions can be found that air exchange rate is an important factor affecting the indoor particle concentration distribution. In the process of indoor free settling(air exchange rate is 0 h-1, the deposition rate were 0.086 h-1, 0.122 h-1, 0.173 h-1 for the particles of 0.5–1.0 μm, 1.0–3.0μm and 3.0–5.0 μm. When the air exchange rate increased to 2.5 h-1, the differences in the attenuation index is significant. There was also a significant linear relationship between air exchange rate and attenuation index. Furthermore, the effect of the slit exhaust strategy on the removal of coarse particles is more remarkable as the increasing air exchange rate.

Validation of a Human Exhalation Flow Simulation in a Room with Vertical Ventilation

DEFF Research Database (Denmark)

Olmedo, Inés; Nielsen, Peter V.; Adana, M. Ruiz de

2012-01-01

flow around persons in combination with the surrounding conditions. Analyses of the flow in the room (macroenvironment) show a number of parameters that play an important role in minimising of airborne cross-infection. The air flow rate to the room must be high, and the air distribution pattern can...... be designed to have high ventilation effectiveness. Furthermore, personalized ventilation may reduce the risk of cross-infection. Personalized ventilation can be used especially in hospital wards, aircraft cabins and, in general, where people are located at defined positions. Analyses of the flow...

Free Convection Personalized Ventilation (FCPV)

DEFF Research Database (Denmark)

Nielsen, Peter V.

Normally we supply fresh air to a room with a diffuser, and this air is distributed in the room according to different principles as: mixing ventilation, displacement ventilation etc. That means we have to supply a very large amount of air to the whole room, although a person in the room totally ...

The use of mechanical ventilation with heat recovery for controlling radon and radon-daughter concentrations

International Nuclear Information System (INIS)

Nazaroff, W.W.; Boegel, M.L.; Hollowell, C.D.; Roseme, G.D.

1980-01-01

An energy research house in Maryland was found to have radon concentrations far in excess of recommended guidelines. A mechanical ventilation system with heat recovery was installed in this house to test its effectiveness as an energy-efficient control technique for indoor radon. Radon concentration was monitored continuously for two weeks under varying ventilation conditions (0.07 to 0.8 air changes per hour (ach)) and radon daughter concentrations were measured by grab-sample techniques about nine times daily during this period. At ventilation rates of 0.6 ach and higher radon and radon daughter levels dropped below guidelines for indoor concentrations. Comparison with other studies indicates that indoor radon buildup may be a problem in a considerable portion of houses characterized by their low infiltration rates. The use of mechanical ventilation systems with air-to-air heat exchangers may offer a practical, cost-effective, and energy-efficient means of alleviating not only the radon problem specifically but also the general deterioration of indoor air quality in houses designed or retrofitted to achieve low infiltration

International Space Station Crew Quarters Ventilation and Acoustic Design Implementation

Science.gov (United States)

Broyan, James L., Jr.; Cady, Scott M; Welsh, David A.

2010-01-01

The International Space Station (ISS) United States Operational Segment has four permanent rack sized ISS Crew Quarters (CQs) providing a private crew member space. The CQs use Node 2 cabin air for ventilation/thermal cooling, as opposed to conditioned ducted air-from the ISS Common Cabin Air Assembly (CCAA) or the ISS fluid cooling loop. Consequently, CQ can only increase the air flow rate to reduce the temperature delta between the cabin and the CQ interior. However, increasing airflow causes increased acoustic noise so efficient airflow distribution is an important design parameter. The CQ utilized a two fan push-pull configuration to ensure fresh air at the crew member's head position and reduce acoustic exposure. The CQ ventilation ducts are conduits to the louder Node 2 cabin aisle way which required significant acoustic mitigation controls. The CQ interior needs to be below noise criteria curve 40 (NC-40). The design implementation of the CQ ventilation system and acoustic mitigation are very inter-related and require consideration of crew comfort balanced with use of interior habitable volume, accommodation of fan failures, and possible crew uses that impact ventilation and acoustic performance. Each CQ required 13% of its total volume and approximately 6% of its total mass to reduce acoustic noise. This paper illustrates the types of model analysis, assumptions, vehicle interactions, and trade-offs required for CQ ventilation and acoustics. Additionally, on-orbit ventilation system performance and initial crew feedback is presented. This approach is applicable to any private enclosed space that the crew will occupy.

REVERSIBLE VENTILATION SYSTEM FOR ADMINISTRATIVE BUILDINGS

Directory of Open Access Journals (Sweden)

Valery Yu. Kravchuk

2017-01-01

Full Text Available Abstract. Objectives To consider the possibility of applying the principle of reversing air flows for a centralised ventilation system; to develop a specific scheme for air exchange reversible ventilation, which will take into account the peculiarities of the microclimate of administrative buildings; to select the type of filling of the air-permeable element and justify this choice; to determine the conditions for changing the direction of air movement in the ventilation system and the area of its application; to form a list of equipment necessary for the operation of such a system; to consider the influence of supply and exhaust devices on the heat and humidity regime of claddings. Methods  To achieve this goal, the published thematic material was reviewed and a patent search carried out using Russian and European databases. Data on mathematical modelling of filtration in porous media and experimental results were used. A method for ventilating rooms in administrative building using the reversal of movement of supply and exhaust air streams along the same channels was applied. Results  Schemas for reversible ventilation systems are presented and their modes of operation considered. It is established that the idea of reversing ventilation flows has not yet been applied in the development of centralised ventilation systems. Based on these published materials, it was concluded that the proposed design of supply and exhaust devices can be used in practice. An original air exchange scheme for the ventilation of administrative buildings and design of supply and exhaust devices for this system are proposed. The conditions for changing the operating modes of the system and the scope of its application are determined. Conclusion The use of the proposed ventilation system allows normative air exchange to be provided without using a supply unit during the cold season. This application of airflow reversal allows the potential of natural forces to be used

Investigation of Indoor Climate in a Naturally Ventilated Office Building

DEFF Research Database (Denmark)

Larsen, Tine Steen; Kalyanova, Olena; Jensen, Rasmus Lund

2008-01-01

A measuring program in a naturally ventilated office building in Copenhagen was carried out to document the indoor climate and ventilation system performance during a year. It included a questionnaire regarding the perceived indoor environmental quality and physical measurements of thermal comfort...... to a combination of poor control of solar shading and a very high local heat load that was above the Danish recommendations for naturally ventilated office buildings. Both measured and perceived indoor air quality in the building was in general very high. The measured air flow rates was relatively high due...... to the need for cooling in the office building, while the level of infiltration was quite low indicating an airtight construction....

Particulate pollution in ventilated space: Analysis of influencing factors

International Nuclear Information System (INIS)

Zhao Bin; Wu Jun

2009-01-01

Particle pollution has been identified to be a major indoor air pollution problem as many epidemiologic evidences have indicated that the particle exposure affects the occupant health. In common practice, mechanical ventilation is introduced to maintain a satisfactory indoor air quality for the occupant, which includes the area of particle control within the space. In order to have an effective control to the indoor particle pollution, it is important to understand the major factors influencing the indoor particle concentration in the breathing zone. This study employs a previously proposed approach to study the particle pollution in a typical ventilation system. The model simultaneously takes into account the interactions between particle transport in ventilation ducts and rooms and particle spatial distribution. It has been proven that an entire ventilation system, including filters, ducts and rooms, can be regarded as a serial of filters in steady-state cases, hence the name 'particle filter group model'. The particle concentration in the breathing zone is calculated under different conditions, and the result is then validated by experimental data. Based on the results, four main factors that affect the particle concentration in the breathing zone are identified, they are fresh air rate, particle filter efficiency, the type of the ventilation duct (roughness) and ventilation modes. Their degrees of influence are analyzed and then the possible measures to improve/control the indoor particle pollution are suggested

Protection of occupants from exhaled infectious agents and floor material emissions in rooms with personalized and underfloor ventilation

DEFF Research Database (Denmark)

Cermak, Radim; Melikov, Arsen Krikor

2007-01-01

the concentration of exhaled air pollution increased in the room. The two types of personalized ventilation performed differently. Subsequent analyses of airborne infection transmission risk indicated that personalized ventilation could become a supplement to traditional methods of infection control....... of pollutants associated with exhaled air and floor material emissions was evaluated at various combinations of personalized and underfloor airflow rates. Compared to underfloor ventilation alone, personalized and underfloor ventilation provided excellent protection Of seated occupants from any pollution, while......The performance of two personalized. ventilation systems supplying air at the breathing zone was tested in conjunction with underfloor ventilation generating two different airflow patterns in a full-scale test room. Two breathing thermal manikins were used to simulate occupants. The distribution...

A Prospective Study of Ventilation Rates and Illness Absence in California Office Buildings

Energy Technology Data Exchange (ETDEWEB)

Eliseeva, Ekaterina A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Spears, Michael [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Chan, Wanyu R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Cohn, Sebastian [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sullivan, Douglas P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Fisk, William J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2014-10-07

Background – This study investigated the associations of ventilation rates (VRs), estimated from indoor CO2 concentrations, in offices with the amount of respiratory infections, illness absences, and building-related health symptoms in occupants. Methods – Office buildings were recruited from three California climate zones. In one or more study spaces within each building, real-time logging sensors measured carbon dioxide, temperature, and relative humidity for one year. Ventilation rates were estimated using daily peak CO2 levels, and also using an alternative metric. Data on occupants and health outcomes were collected through web-based surveys every three months. Multivariate models were used to assess relationships between metrics of ventilation rate or CO2 and occupant outcomes. For all outcomes, negative associations were hypothesized with VR metrics, and positive associations with CO2 metrics. Results – Difficulty recruiting buildings and low survey response limited sample size and study power. In 16 studied spaces within 9 office buildings, VRs were uniformly high over the year, from twice to over nine times the California office VR standard (7 L/s or 15 cfm per person). VR and CO2 metrics had no statistically significant relationships with occupant outcomes, except for a small significantly positive association of the alternative VR metric with respiratory illness-related absence, contrary to hypotheses. Conclusions– The very high time-averaged VRs in the California office buildings studied presumably resulted from “economizer cycles” bringing in large volumes of outdoor air; however, in almost all buildings even the estimated minimum VRs supplied (without the economizer) substantially exceeded the minimum required VR. These high VRs may explain the absence of hypothesized relationships with occupant outcomes. Among uniformly high VRs, little variation in contaminant concentration and occupant effects would be expected. These findings may

Displacement Ventilation

DEFF Research Database (Denmark)

Nielsen, Peter Vilhelm

Displacement ventilation is an interesting new type of air distribution principle which should be considered in connection with design of comfort ventilation in both smal1 and large spaces. Research activities on displacement ventilation are large all over the world and new knowledge of design...... methods appears continuously. This book gives an easy introduction to the basis of displacement ventilation and the chapters are written in the order which is used in a design procedure. The main text is extended by five appendices which show some of the new research activities taking place at Aalborg...

Ventilation system for 99Mo production apparatus

International Nuclear Information System (INIS)

Izumo, Mishiroku; Okane, Shougo; Sorita, Takami; Aoyama, Saburou

1978-04-01

In production of 20 Ci 99 Mo from 235 U fission, about 120 Ci of radioiodine ( 131 I, 132 I, and 133 I) is involved. To remove airborne radioiodine from the exhaust air from production apparatus and minimize radioiodine release to the atmosphere, the ventilation system is equipped with 2 units of Model-FD charcoal filter (KI 3 -Impregnated charcoal 2 inch thick of Barnebey-Cheney Co.). From September 1976 to December 1977, 21 runs of 99 Mo production involving airborne radioiodine were carried out. The ventilation system was operated continuously for the whole 15 months period; variation in removal efficiency of airborne radioiodine from the exhaust air stream was observed. In the runs valuable experiences were gained in operation and maintenance of the ventilation system including activated charcoal filter and health-physics management of such facility. Following are the results: (1) Airborne radioiodine from 99 Mo production apparatus is reduced to 10 -3 % of the original quantity. (2) When the ventilation system is operated at a maximum air flow rate through the filter, the average efficiency during 15 months is over 98%. (3) Airborne radioiodine released from 99 Mo production apparatus to the ventilation system is less than 5% particulate iodine and alkyl iodines and more than 95% inorganic iodine. (4) Airborne radioiodine released from the stack is less than 28 μCi/run, which is below the limit in regulations on Radioisotope Production Laboratory. (auth.)

Adaptive Support Ventilation May Deliver Unwanted Respiratory Rate-Tidal Volume Combinations in Patients with Acute Lung Injury Ventilated According to an Open Lung Concept

NARCIS (Netherlands)

Dongelmans, Dave A.; Paulus, Frederique; Veelo, Denise P.; Binnekade, Jan M.; Vroom, Margreeth B.; Schultz, Marcus J.

2011-01-01

Background: With adaptive support ventilation, respiratory rate and tidal volume (V(T)) are a function of the Otis least work of breathing formula. We hypothesized that adaptive support ventilation in an open lung ventilator strategy would deliver higher V(T)s to patients with acute lung injury.

Feasibility of utilising solar-induced ventilation in Malaysia

International Nuclear Information System (INIS)

Ong, K.S.; Chow, C.C.

2006-01-01

The feasibility of applying solar-induced ventilation in a typical Malaysian house measuring 3 m high x wide x 5 m deep was considered based on experimental results obtained from a laboratory-scale model. A wall-type solar chimney was considered. The design of the solar chimney incorporated providing a glass panel alongside a vertical wall of a building. Openings at the top and bottom of the wall allowed fresh air to be introduced into the building. Simulations obtained from a simple theoretical model showed that the solar chimney was able to induce air flow rates of between 640 to 1040 m3 h-1 with a 0.3 m air gap. These ventilation rates are found to be in compliance with codes specified by ASHRAE and the Uniform Building By-laws. Full scale studies would need to be conducted in order to evaluate its effectiveness especially the flow pattern in the room

Synchronized mechanical ventilation for respiratory support in newborn infants.

Science.gov (United States)

Greenough, Anne; Murthy, Vadivelam; Milner, Anthony D; Rossor, Thomas E; Sundaresan, Adesh

2016-08-19

During synchronised mechanical ventilation, positive airway pressure and spontaneous inspiration coincide. If synchronous ventilation is provoked, adequate gas exchange should be achieved at lower peak airway pressures, potentially reducing baro/volutrauma, air leak and bronchopulmonary dysplasia. Synchronous ventilation can potentially be achieved by manipulation of rate and inspiratory time during conventional ventilation and employment of patient-triggered ventilation. To compare the efficacy of:(i) synchronised mechanical ventilation, delivered as high-frequency positive pressure ventilation (HFPPV) or patient-triggered ventilation (assist control ventilation (ACV) and synchronous intermittent mandatory ventilation (SIMV)), with conventional ventilation or high-frequency oscillation (HFO);(ii) different types of triggered ventilation (ACV, SIMV, pressure-regulated volume control ventilation (PRVCV), SIMV with pressure support (PS) and pressure support ventilation (PSV)). We used the standard search strategy of the Cochrane Neonatal Review group to search the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 5), MEDLINE via PubMed (1966 to June 5 2016), EMBASE (1980 to June 5 2016), and CINAHL (1982 to June 5 2016). We also searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials. Randomised or quasi-randomised clinical trials comparing synchronised ventilation delivered as HFPPV to CMV, or ACV/SIMV to CMV or HFO in neonates. Randomised trials comparing different triggered ventilation modes (ACV, SIMV, SIMV plus PS, PRVCV and PSV) in neonates. Data were collected regarding clinical outcomes including mortality, air leaks (pneumothorax or pulmonary interstitial emphysema (PIE)), severe intraventricular haemorrhage (grades 3 and 4), bronchopulmonary dysplasia (BPD) (oxygen dependency beyond 28 days), moderate/severe BPD (oxygen

VENTILATION TECHNOLOGY SYSTEMS ANALYSIS

Science.gov (United States)

The report gives results of a project to develop a systems analysis of ventilation technology and provide a state-of-the-art assessment of ventilation and indoor air quality (IAQ) research needs. (NOTE: Ventilation technology is defined as the hardware necessary to bring outdoor ...

Liquid ventilation.

Science.gov (United States)

Sarkar, Suman; Paswan, Anil; Prakas, S

2014-01-01

Human have lungs to breathe air and they have no gills to breath liquids like fish. When the surface tension at the air-liquid interface of the lung increases as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen as the inert carrier of oxygen and carbon dioxide offers a number of advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. It is well-known that respiratory diseases are one of the most common causes of morbidity and mortality in intensive care unit. During the past few years several new modalities of treatment have been introduced. One of them and probably the most fascinating, is of LV. Partial LV, on which much of the existing research has concentrated, requires partial filling of lungs with perfluorocarbons (PFC's) and ventilation with gas tidal volumes using conventional mechanical ventilators. Various physico-chemical properties of PFC's make them the ideal media. It results in a dramatic improvement in lung compliance and oxygenation and decline in mean airway pressure and oxygen requirements. No long-term side-effect reported.

Formaldehyde and acetaldehyde exposure mitigation in US residences: In-home measurements of ventilation control and source control

Energy Technology Data Exchange (ETDEWEB)

Hult, Erin L. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Willem, Henry [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Price, Phillip N. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Hotchi, Toshifumi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Russell, Marion L. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Singer, Brett C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2014-10-01

Measurements were taken in new US residences to assess the extent to which ventilation and source control can mitigate formaldehyde exposure. Increasing ventilation consistently lowered indoor formaldehyde concentrations. However, at a reference air exchange rate of 0.35 h^-1, increasing ventilation was up to 60% less effective than would be predicted if the emission rate were constant. This is consistent with formaldehyde emission rates decreasing as air concentrations increase, as observed in chamber studies. In contrast, measurements suggest acetaldehyde emission was independent of ventilation rate. To evaluate the effectiveness of source control, formaldehyde concentrations were measured in Leadership in Energy and Environmental Design (LEED) certified/Indoor airPLUS homes constructed with materials certified to have low emission rates of volatile organic compounds (VOC). At a reference air exchange rate of 0.35 h^-1, and adjusting for home age, temperature and relative humidity, formaldehyde concentrations in homes built with low-VOC materials were 42% lower on average than in reference new homes with conventional building materials. Without adjustment, concentrations were 27% lower in the low-VOC homes. The mean and standard deviation of formaldehyde concentration were 33 μg m-3 and 22 μg m^-3 for low-VOC homes and 45 μg m^-3 and 30 μg m^-3 for conventional.

Recommended Ventilation Strategies for Energy-Efficient Production Homes

Energy Technology Data Exchange (ETDEWEB)

Roberson, J.; Brown, R.; Koomey, J.; Warner, J.; Greenberg, S.

1998-12-01

This report evaluates residential ventilation systems for the U.S. Environmental Protection Agency's (EPA's) ENERGY STAR{reg_sign} Homes program and recommends mechanical ventilation strategies for new, low-infiltration, energy-efficient, single-family, ENERGY STAR production (site-built tract) homes in four climates: cold, mixed (cold and hot), hot humid, and hot arid. Our group in the Energy Analysis Department at Lawrence Berkeley National Lab compared residential ventilation strategies in four climates according to three criteria: total annualized costs (the sum of annualized capital cost and annual operating cost), predominant indoor pressure induced by the ventilation system, and distribution of ventilation air within the home. The mechanical ventilation systems modeled deliver 0.35 air changes per hour continuously, regardless of actual infiltration or occupant window-opening behavior. Based on the assumptions and analysis described in this report, we recommend independently ducted multi-port supply ventilation in all climates except cold because this strategy provides the safety and health benefits of positive indoor pressure as well as the ability to dehumidify and filter ventilation air. In cold climates, we recommend that multi-port supply ventilation be balanced by a single-port exhaust ventilation fan, and that builders offer balanced heat-recovery ventilation to buyers as an optional upgrade. For builders who continue to install forced-air integrated supply ventilation, we recommend ensuring ducts are airtight or in conditioned space, installing a control that automatically operates the forced-air fan 15-20 minutes during each hour that the fan does not operate for heating or cooling, and offering ICM forced-air fans to home buyers as an upgrade.

The impact of temperature on mean local air age and thermal comfort in a stratum ventilated office

Energy Technology Data Exchange (ETDEWEB)

Tian, Lin; Lin, Zhang; Yao, Ting [Building Energy and Environmental Technology Research Unit, School of Energy and Environment and Division of Building Science and Technology, City University of Hong Kong, Hong Kong SAR (China); Liu, Jing; Wang, Qiuwang [State Key Lab of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, Xi' an, 710049 (China)

2011-02-15

The influence of the supply air temperature on the mean local air age and thermal comfort of a typical individual office under stratum ventilation is investigated by a numerical method, which is validated by an experiment carried out by the authors. The results show that for an office, when the supply air temperature is increased from 19 C to 21 C, the corresponding mean occupied zone temperature rises from 24.5 C to 26.5 C. The inhaled air quality for the occupant is improved when supply air temperature rises from 19 C to 21 C. Also, the thermal comfort indices (predicted mean vote or PMV, predicted percentage of dissatisfied or PPD and predicted dissatisfied or PD) fulfill the requirements of ISO 7730 and CR 175 1998. For summer cooling operation, stratum ventilation may offer a feasible solution to elevated indoor temperatures, which are recommended by several governments in East Asia. (author)

Subsurface Ventilation System Description Document

Energy Technology Data Exchange (ETDEWEB)

Eric Loros

2001-07-25

The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development and emplacement areas. The system provides fresh air for a safe work environment and supports potential retrieval operations by ventilating and cooling emplacement drifts. The system maintains compliance within the limits established for approved air quality standards. The system maintains separate ventilation between the development and waste emplacement areas. The system shall remove a portion of the heat generated by the waste packages during preclosure to support thermal goals. The system provides temperature control by reducing drift temperature to support potential retrieval operations. The ventilation system has the capability to ventilate selected drifts during emplacement and retrieval operations. The Subsurface Facility System is the main interface with the Subsurface Ventilation System. The location of the ducting, seals, filters, fans, emplacement doors, regulators, and electronic controls are within the envelope created by the Ground Control System in the Subsurface Facility System. The Subsurface Ventilation System also interfaces with the Subsurface Electrical System for power, the Monitored Geologic Repository Operations Monitoring and Control System to ensure proper and safe operation, the Safeguards and Security System for access to the emplacement drifts, the Subsurface Fire Protection System for fire safety, the Emplacement Drift System for repository performance, and the Backfill Emplacement and Subsurface Excavation Systems to support ventilation needs.

Subsurface Ventilation System Description Document

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-10-12

The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development and emplacement areas. The system provides fresh air for a safe work environment and supports potential retrieval operations by ventilating and cooling emplacement drifts. The system maintains compliance within the limits established for approved air quality standards. The system maintains separate ventilation between the development and waste emplacement areas. The system shall remove a portion of the heat generated by the waste packages during preclosure to support thermal goals. The system provides temperature control by reducing drift temperature to support potential retrieval operations. The ventilation system has the capability to ventilate selected drifts during emplacement and retrieval operations. The Subsurface Facility System is the main interface with the Subsurface Ventilation System. The location of the ducting, seals, filters, fans, emplacement doors, regulators, and electronic controls are within the envelope created by the Ground Control System in the Subsurface Facility System. The Subsurface Ventilation System also interfaces with the Subsurface Electrical System for power, the Monitored Geologic Repository Operations Monitoring and Control System to ensure proper and safe operation, the Safeguards and Security System for access to the emplacement drifts, the Subsurface Fire Protection System for fire safety, the Emplacement Drift System for repository performance, and the Backfill Emplacement and Subsurface Excavation Systems to support ventilation needs.

Low resource ventilation unit; Ressourcebesparende ventilationsenhed

Energy Technology Data Exchange (ETDEWEB)

Drivsholm, C.

2012-03-15

In the project a resource-saving ventilation device was developed which is based on the use of a regenerator and a reversible air flow. The regenerator is placed in the building envelope, and the concept works in the way that the heat in the air during ventilation is stored in the regenerator and brought back into the building by a reversible air change. The heated air is blown from inside the building out through the regenerator. In this way the regenerator accumulates the heat in the air. Over a period of 30-120 seconds, the regenerator capacity is utilized. When the regenerator cannot be further heated, the air flow is reversed and there is now blown cold air through the regenerator. Thereby the heat from the regenerator is released to the cold fresh air. Thus, the fresh air brings heat back into the building, whereby the air is replaced with a limited heat loss. Ventilation with a regenerator is described as micro-ventilation. The developed micro-ventilation unit was tested by the Danish Technological Institute. The test results shows that the unit performs according to expectations: 1) The heat recovery is 85%; 2) The flow through the unit is 80m3 per hour in a 5 section unit; 3) The noise level is 30 db(A) in a representative room; 4) The energy consumption is <300 J/m3. The unit is introduced into the market, and the first plants have been sold. (LN)

Numerical investigation of diffuse ceiling ventilation in an office under different operating conditions

DEFF Research Database (Denmark)

Hviid, Christian Anker; Petersen, Steffen

2014-01-01

is a numerical study of the performance of a six person office equipped with diffuse ventilation ceiling. In total six extreme, yet realistic, operation scenarios were simulated to study the performance including different occupancy, ventilation rates and supply air temperatures. The performance was studied...

Ventilated air cavities for the control of rising damp in historical buildings. Functional analysis

Directory of Open Access Journals (Sweden)

Mª T. Gil Muñoz

2018-01-01

Full Text Available This study analyzes the behavior of ventilated air cavities and their level of efficiency when used for the control of rising damp and the associated pathological damage in walls and foundations of historical buildings. The methodology is based on experiments on-site and monitoring. Knowledge of local climate conditions, the surroundings of the building, its construction features and the type of foundation constitute the preliminary conditions for the monitoring. In order to reach the goal we have measured several parameters according to a plan, developed graphical tools for the study, and prepared statistical data. The building of this system has not always been accompanied by a thorough assessment that would justify the intervention. The results show how this situation has affected the design strategies and sizing of the ventilated air cavities, limiting in many cases their efficiency.

Evaluation of simplified ventilation system with direct air supply through the facade in a school in a cold climate

Energy Technology Data Exchange (ETDEWEB)

Mysen, M. [Norwegian Building Research Institute, Blindern, Oslo (Norway); Department of Energy and Process Technology, Norwegian University of Science and Technology (NTNU), Trondheim (Norway); Schild, P. G.; Hellstrand, V.; Thunshelle, K. [Norwegian Building Research Institute, Blindern, Oslo (Norway)

2004-07-01

Many educational buildings in industrialised countries have poor indoor climate, according to today's knowledge about the impact of indoor climate on well-being and productivity. Budget restrictions and practical limitations such as lack of space for central air handling units and ventilation ducts, have motivated the application of simplified ventilation systems in some schools, such as taking unconditioned supply air directly from the facade. One such school was recently evaluated in Norway. On cold days, thermal comfort in the classroom deteriorated due to cold down draught from the supply outlet. In addition, moist and fertile conditions for microbiological growth were observed in the air supply ductwork. On the other hand the same pupils are more satisfied with the school and have less sick building syndrome (SBS) symptoms during winter than summer. An improved control strategy with a temperature-compensated CO{sub 2} set-point for controlling the air flow is suggested. This could improve thermal comfort and reduce energy use without compromising perceived air quality (PAQ) during cold weather. Furthermore it could improve indoor air quality (IAQ) during warm weather with only a slight increase of energy use. Further evaluation of an improved solution is needed before such a ventilation concept can be recommended in cold climates. (author)

Personalized ventilation

DEFF Research Database (Denmark)

Melikov, Arsen Krikor

2004-01-01

microenvironment. Furthermore, HVAC systems should be designed to protect occupants from airborne transmission of infectious agents that may be present in exhaled air. Personalized ventilation is a new development in the field of HVAC and has the potential to fulfill the above requirements. This paper reviews...... existing knowledge on performance of personalized ventilation (PV) and on human response to it. The airflow interaction in the vicinity of the human body is analyzed and its impact on thermal comfort and inhaled air quality is discussed together with control strategies and the application of PV in practice...

Indoor climate and the performance of ventilation in Finnish residences

International Nuclear Information System (INIS)

Ruotsalainen, R.; Roennberg, R.; Saeteri, J.; Majanen, A.; Seppaenen, O.; Jaakkola, J.J.K.

1992-01-01

The purpose of the study was to gather information about the actual ventilation and indoor air quality and to evaluate the differences between houses and apartments with different ventilation systems. A sample of 242 dwellings in the Helsinki metropolitan area was studied over periods of two weeks during the 1988-1989 heating season. The mean air-exchange rates had a high variation (average 0.52 l/h, range 0.07-1.55 l/h). The ASHRAE minimum value of 0.35 l/h was not achieved in 28% of the dwellings. The air-exchange rates were significantly lower in the houses than in the apartments (averages 0.45/0.64 l/h, p 3 (range 5-866 Bq/m 3 ); the Finnish target value of 200 Bq/m 3 was exceeded in 17% of the houses but in none of the apartments. The measurements indicate that the indoor air quality in Finnish dwellings is not always satisfactory with reference to human health and comfort. (au)

VENTILATION MODEL

International Nuclear Information System (INIS)

V. Chipman

2002-01-01

The purpose of the Ventilation Model is to simulate the heat transfer processes in and around waste emplacement drifts during periods of forced ventilation. The model evaluates the effects of emplacement drift ventilation on the thermal conditions in the emplacement drifts and surrounding rock mass, and calculates the heat removal by ventilation as a measure of the viability of ventilation to delay the onset of peak repository temperature and reduce its magnitude. The heat removal by ventilation is temporally and spatially dependent, and is expressed as the fraction of heat carried away by the ventilation air compared to the fraction of heat produced by radionuclide decay. One minus the heat removal is called the wall heat fraction, or the remaining amount of heat that is transferred via conduction to the surrounding rock mass. Downstream models, such as the ''Multiscale Thermohydrologic Model'' (BSC 2001), use the wall heat fractions as outputted from the Ventilation Model to initialize their postclosure analyses

The Maintenance of Heating, Ventilating and Air-Conditioning Systems and Indoor Air Quality in Schools: A Guide for School Facility Managers. Technical Bulletin.

Science.gov (United States)

Wheeler, Arthur E.

To help maintain good indoor air quality (IAQ) in schools, guidance for the development and implementation of an effective program for maintenance and operation of heating, ventilating, and air-conditioning (HVAC) systems are discussed. Frequently, a building's occupants will complain about IAQ when the temperature or humidity are at uncomfortable…

Dynamic model of counter flow air to air heat exchanger for comfort ventilation with condensation and frost formation

DEFF Research Database (Denmark)

Nielsen, Toke Rammer; Rose, Jørgen; Kragh, Jesper

2009-01-01

must be calculated under conditions with condensation and freezing. This article presents a dynamic model of a counter flow air to air heat exchanger taking into account condensation and freezing and melting of ice. The model is implemented in Simulink and results are compared to measurements......In cold climates heat recovery in the ventilation system is essential to reduce heating energy demand. Condensation and freezing occur often in efficient heat exchangers used in cold climates. To develop efficient heat exchangers and defrosting strategies for cold climates, heat and mass transfer...

International Space Station USOS Crew Quarters Ventilation and Acoustic Design Implementation

Science.gov (United States)

Broyan, James Lee, Jr.

2009-01-01

The International Space Station (ISS) United States Operational Segment (USOS) has four permanent rack sized ISS Crew Quarters (CQ) providing a private crewmember space. The CQ uses Node 2 cabin air for ventilation/thermal cooling, as opposed to conditioned ducted air from the ISS Temperature Humidity Control System or the ISS fluid cooling loop connections. Consequently, CQ can only increase the air flow rate to reduce the temperature delta between the cabin and the CQ interior. However, increasing airflow causes increased acoustic noise so efficient airflow distribution is an important design parameter. The CQ utilized a two fan push-pull configuration to ensure fresh air at the crewmember s head position and reduce acoustic exposure. The CQ interior needs to be below Noise Curve 40 (NC-40). The CQ ventilation ducts are open to the significantly louder Node 2 cabin aisle way which required significantly acoustic mitigation controls. The design implementation of the CQ ventilation system and acoustic mitigation are very inter-related and require consideration of crew comfort balanced with use of interior habitable volume, accommodation of fan failures, and possible crew uses that impact ventilation and acoustic performance. This paper illustrates the types of model analysis, assumptions, vehicle interactions, and trade-offs required for CQ ventilation and acoustics. Additionally, on-orbit ventilation system performance and initial crew feedback is presented. This approach is applicable to any private enclosed space that the crew will occupy.