Location of Exhausts and Inlets
#NO 17 The effect of wind on energy consumption in buildings.
AUTHOR Arens E.A. Williams P.B.
BIBINF Energy & Bldgs. May 1977, 1, (1), 77-84, 7 figs, 13 refs. #DATE 01:05:1977 in English
ABSTRACT Treats 4 mechanisms of building heat exchange with the environment and their effect on overall energy consumption: 1) air infiltration and exfiltration, pressure distributions and gradients and resulting mass transfer at building surfaces; 2) influence on surface heat transmission of turbulent mixing of air close to building surface and mechanisms causing this mixing; 3) how air circulation around buildings strongly affects air conditioning cooling towers and how incorrect location of ventilation inlets and exhausts can reduce thermal efficiencies of cooling equipment and increase fan power requirements; 4) results of enclosing spaces such as shopping centres.
KEYWORDS heat transfer, air infiltration, pressure distribution, air flow, turbulence.
#NO 1400 A field study of infiltration-induced variations in the heating of apartments.
AUTHOR Latta J.K.
BIBINF NRCC Building Research Note No.202 April 1983 8pp. 6 figs. 1 ref. #DATE 01:04:1983 in English
ABSTRACT Makes a field study of energy consumption in 3 electrically heated high rise apartment buildings in Chicago, to see if stack effect causes significant variations in the heating requirements of apartments according to their location in tall buildings. The buildings have 30, 42, and 45 floors, and theheating consumption for December through March is computed and plotted against floor number. Results show that normal stack effect is suppressed in a tall apartment building when supply and exhaust fans are running. Since the effect on heating consumption is weak in buildings of over 40 storys, it is probably negligible in the more common case of apartment buildings of 20 storys or less.
KEYWORDS high rise building,stack effect, air infiltration,
#NO 1600 Performance of passive ventilation systems in a two-storey house.
AUTHOR Shaw C Y, Kim A.
BIBINF 5th AIC Conference 'The implementation and effectiveness of air infiltration standards in buildings' Reno, Nevada, 1-4 October 1984, pp11.1-11.27, 17 figs, 2 tabs, 6 refs. #DATE 00:10:1984 in English
ABSTRACT Air change rates were measured in one two-storey detached house with five basic types of passive ventilation systems: an intake vent in the basement wall, an outdoor air supply ducted to the existing forced air heating system, an exhaust stack extending from the basement to the roof, and two combinations of the supply systems and the exhaust stack. An expression was developed for estimating house air change rate from house airtightness, neutral pressure level and indoor-outdoor air temperature difference. Good agreement was obtained for the test house between the predicted and the measured air change rates. The effects of furnace fan operation, air distribution system, and sizeand location of vent openings on house air change rates are also discussed.
KEYWORDS detached house, air change rate, air tightness, neutral pressure level, temperature difference, natural ventilation, stack effect
#NO 2308 Inhabitant behaviour with regard to mechanical ventilation in France.
AUTHOR Bienfait D, Moye Cl
BIBINF 7th AIVC Conference,"Occupant interaction with ventilation systems", 29 September - 2 October 1986, Stratford on Avon, UK, Bracknell, AIVC, 1986, p7.1-7.17, 9 figs, 7 refs.
#DATE 00:09:1986 in English AIVC bk
ABSTRACT In France, most of the ventilation systems in dwellings now consist of exhaust vents linked up with a fan, and air inlets. A survey conducted by the CSTB shows that actual ventilation rates are frequently different from prescribed values and that a lot of problems encountered are related to occupant behaviour. The duration of exhaust flowrate peak value was measured; it was shown that this duration was dependent on the kind of command and its location in the room. Draughts through air inlets were a major concern. A lot of air vents did not operate correctly because of fouling. Reasons were that theinhabitants had not always a high consciousness of the necessity of cleaning, and that, moreover, a lot of air vents were not easily dismountable. Among conclusions of the survey, are the following: air vents should be easily dismountable for cleaning and recommendations for it should be given to the inhabitants; air inlets, exhaust vents and fan command should be correctly located.
KEYWORDS residential building, ventilation rate, occupant behaviour, air vent
#NO 2543 Identifying and avoiding indoor air quality problems.
AUTHOR Turner W A, Bearg D
BIBINF Heat Pip Air Condit, February 1987, p45-49, 4 refs. #DATE 00:02:1987 in English
ABSTRACT This article outlines a methodology that has proved useful for building evaluations where there is no identifiable suspected source of air contaminants causing complaints or situations where there is an identifiable suspected source but unknown pathways of transmission. It draws upon illustrative case studies to show how the parameters discussed have contributed to various cases of degraded indoor air quality. Lists some of the typically more important indoor air contaminants to be considered, eg particles, combustion gases, ozone, biological sources, organic chemicals, fibres. Also lists outside building sources (radon, loading docks, parking lots, cooling towers, localized exhaust systems), and mechanical system sources (location of air intakes, humidity control, location of supply and exhaust registers). If the evaluation of ventilation rates and the determination of air movement pathways are not sufficient to deduce the source of air contaminants, further specific sensitive measurements of source and contaminant concentrations can be employed. The techniques and procedures described have been used by the authors to investigate several buildings with histories of occupant complaints. These buildings had "passed" OSHA type surveys with flying colours, and yet when looked at very closely as 'office buildings' they had situations occurring that were causing irritation and discomfort to the occupants. Solutions have been developed from these investigations that have eliminated or minimized both the problems and complaints.
KEYWORDS indoor air quality, office building, ventilation rate, carbon dioxide, tracer gas, pollutant, mechanical ventilation, air movement
#NO 2727 Measuring ventilation efficiency.
Maling af ventilationseffektivitet.
AUTHOR Breum N O
BIBINF Copenhagen, Arbejdsmiljofondet, 1987, 138p, figs, tabs, 99 refs. #DATE 00:00:1987 in Danish
ABSTRACT The measurement of ventilation by the tracer gas technique is a well established practice, and several analytical models are available. For practical purposes a simple technique of measurement and calculation is of importance. In the present study a portable measurement unit was developed for field studies. A multipoint sampler (8 channels), a gas analyser (digital alternatively analogue output) and a portable personal computer (IBM compatible) are the main components of the unit. In the field measurements are initialised by menu-driven software allowing free choice of input(digital/analogue), type of tracer gas, sampling sequence, number of sampling points etc. The software also allows a free text sampling point specification. As data are collected updated concentration profiles are displayed. Several analytical models are implemented in the software: efficiency of a local exhaust system, efficiency of room ventilation, two compartment model, transfer index and age analysis. Estimated parameters and functional relationships are displayed and a printout is available on location. Results of field studies are included in the report.
KEYWORDS ventilation efficiency, measurement technique, instrumentation, computer
#NO 2816 Turbulent air flow measurements in ventilated spaces.
AUTHOR Kovanen K, Seppanen O, Siren K, et al
BIBINF in: Indoor Air'87, Proceedings of the 4th International Conference on Indoor Air Quality and Climate, Berlin (West), 17-21 August 1987, Vol 3, Institute for Water, Soil and Air Hygiene, 1987, p329-333, 1 fig, 2 tabs, 3 refs.
#DATE 00:00:1987 in English
ABSTRACT The purpose of the present study is to investigate the characteristics of turbulent air flow in the occupied zone of ventilated spaces: air velocity, standard deviation, turbulence intensity and fluctuation frequency. The study is accomplished by making field measurements in dwellings and offices with various ventilation and air distribution systems. Rooms with only most typical supply and exhaust devices were chosen for the study. In each space probes were placed at least at three locations in the occupied zone. At each location, measurements were performed at four heights: 0.05, 0.15, 1.1 and1.7m above the floor level. The relationship between the mean velocity and the standard deviation was calculated at every four heights. The instrumentation was designed and built in the laboratory of Heating, Ventilating and Air Conditioning of Helsinki University of Technology. In order to analyse fluctuation frequencies a computer program that uses Fast Fourier Transform method, was developed. The paper will comprise the summary of results anddiscuss the influence of air distribution and ventilation system on the measured factors.
KEYWORDS turbulent air flow, instrumentation
#NO 2910 Building assessment techniques for indoor air quality evaluations.
AUTHOR Bearg D W, Turner W A
BIBINF in: Indoor air quality in cold climates: hazards and abatement measures. APCA Specialty Conference 1986, p276-283, 4 refs. #DATE 00:00:1986 in English
ABSTRACT Techniques for indoor air quality evaluations are presented and discussed. The techniques presented first focus on procedures to determine effective ventilation rates and pathways of air movement within the building. This is followed by a discussion of assessment techniques to identify potential sources of air contaminants. These sources can then be categorized with respect to their originating location. Air contaminants can arise from withinthe building, outside the building, from the mechanical ventilation system, or from localized exhaust systems. The procedures associated with these techniques include the survey of carbon dioxide concentrations to determine effective ventilation rates and outdoor air makeup, the use of enthalpy balance to determine mixing ratios and visual determinations using air current tubes. This technique is useful for building evaluations where there is no identifiable suspected source of air contaminants causing complaints or situations where there is an identifiable suspected source but unknown pathways of transmission. This paper will draw upon illustrative case studies to show how the parameters discussed have contributed to various cases of degraded indoor air quality.
KEYWORDS indoor air quality, ventilation rate, air movement, pollutant, mechanical ventilation, carbon dioxide
#NO 2914 Ventilation intake air contamination by nearby exhausts.
AUTHOR Wilson D J
BIBINF in: Indoor air quality in cold climates: hazards and abatement measures. APCA Specialty Conference 1986, p 335-347, 6 figs, 11 refs. #DATE 00:00:1986 in English
ABSTRACT Buildings with mechanical ventilation systems often place air intakes and exhausts close to each other to make the most efficient use of space. This is particularly true for direct air-to-air exchangers for exhaust heat recovery. The greatest hazards occur for exhausts on laboratories, hospitals andindustrial buildings where concentrated emissions of solvents, toxic gases and pathogens are carried by the wind or their own momentum from exhaust to intakes. Tracer gas studies in wind tunnel simulations are reviewed, and correlated to show the contributions of exhaust jet plume rise, building induced turbulence, and large scale atmospheric turbulence on dilution between an exhaust and an intake. Measurements show that the two major factors that influence dilution are distance between exhaust and intake, and the ratio of exhaust jet velocity to windspeed. The location of the exhaust intake pair on the building is also important, with good design placing the intake on the lower third of the building and the exhaust on the upper two thirds. Flow visualization tests show the reason for this. A simple theory for exhaust to intake dilution is presented. The theory, which accounts for dilution close to the exhaust, is in good agreement with wind tunnel data, and with full scale tracer gas tests on large buildings. The implications for hood design of closely spaced exhausts and intakes are discussed. It is shown that the fraction of recirculated exhaust in intake air can change by a factor of five with only minor changes in design, such as the removal of a rain cap.
KEYWORDS mechanical ventilation, laboratory, hospital, industrial building, toxic gas, tracer gas, wind tunnel
#NO 3227 Elimination of waste anaesthetic gases from operating theatres.
AUTHOR Breum N O, Kann T
BIBINF Acta Anaesthesiol Scand, No 32, 1988, pp388-390, 2 figs, 1 tab, 14 refs. #DATE 00:00:1988 in English
ABSTRACT At present, waste anaesthetic gases in the operating theatre are eliminated by room ventilation and by additional measures such as scavenging by a double-mask system and a local exhaust system. A simple technique is proposed for measuring the capture efficiency (E) of different scavenging systems. E is the ratio of the waste anaesthetic gases captured by a system to the totalquantity of waste anaesthetic gases produced. In a field study on existing unmodified systems, E from a phantom pollutant source was measured using a portable measuring unit designed for displaying test results on location. The pollutant source was a leaking double-mask system. When scavenging from the double-mask system, E was 98% at an exhausted airflow of 28-33 m3/h. Using a local exhaust system at an airflow of 30 m3/h, E ranged from 20 to 96%, depending on the distance between the mask and the nozzle of the exhaust system.
KEYWORDS pollutant, ventilation effectiveness, air flow, ventilation rate
#NO 3562 Ventilation and airtightness in energy balance analyses
AUTHOR Blomsterberg A
BIBINF in:UK, AIVC, 10th AIVC Conference, held at Espoo, Finland, 25-28 September 1989, Volume 1, February 1990, pp305-324, 4 tabs, 3 refs. #DATE 00:02:1990 in English
ABSTRACT Ventilation in buildings occurs as a consequence of natural air infiltration and through the use of purpose provided ventilation. The air infiltration part of ventilation is often difficult to determine for different boundary conditions. The influence of ventilation on the energy balance of a residential building is therefore usually determined as a remainder together with internal gains from people and the sun or given a constant value. This paper summarizes a report, on one-family houses, on: - the influence of ventilation and airtightness on the energy balance - methods of separating out the ventilation losses from the energy balance - the performance of different ventilation systems. The results are based on performance monitoring and evaluation during two years of four modern one-family houses with different ventilation systems. Two of the houses are equipped with mechanical exhaust-supply ventilation and two with mechanical exhaust ventilation. The ventilation systems were studied during several one-week periods using the constant concentration tracer gas technique. The airtightness of the houses was examined using the fan pressurization technique. The ventilation was predicted with a simplified theoretical one-zone model (the LBL-model) and a multi-zone network model (MOVECOMP). The energy balance was simulated with a dynamic simulation model (STAWAD). The following conclusions are valid for the examined houses. A simplified theoretical one-zone model can be useful and make accurate estimations of the air infiltration in tight houses with mechanical ventilation. This is also a very straightforward kind of model to employ. For less tight houses a multi-zone network model can be useful. There are however two problems with a multi-zone network model; it is time-consuming to put together all the inputs needed and there isn't enough data as to wind pressure and the location of leakage paths available.
KEYWORDS energy balance, mechanical ventilation, constant concentration, fan pressurisation
#NO 3738 Comparison of modulated versus nonmodulated control systems for sidewall air inlets in a naturally ventilated swine barn.
AUTHOR Choiniere Y, Blais F, Munroe J A
BIBINF Canada, Canadian Society of Agricultural Engineering, May 1987, 23 pp, 8 figs, 4 tabs, 18 refs. #DATE 00:05:1987 in English
ABSTRACT Two inlet control systems for a naturally ventilated swine finishing barn were compared during winter on the basis of temperature regulation, CO2 and NH3 concentrations, and electricity consumption. The barn was fitted with continuous above-centre pivot rotating doors in the sidewalls and a continuous ridge opening. The nonmodulated system used thermostats, compressed air, and air cylinders to totally open or close the air inlets. Barn temperature fluctuations of 6-10 deg C within a 30 to 35 minute period were noted for any given location. CO2 concentrations ranged between 1500 and 3500 ppm depending on whether the inlets were open or closed. NH3 remained rather constant at 6-8 ppm. The modulated control system used thermostats, a gear motor, and a time delay to step the inlets open and closed. At animal level, barn temperature fluctuations of about 1-3 deg C were noted for any given location. CO2 concentrations ranged from 2800-3200 ppm, and NH3 concentrations from 5-7 ppm.
KEYWORDS natural ventilation, animal house, carbon dioxide
#NO 3875 Infiltration in Norwegian buildings.
AUTHOR Brunsell J T, Fossdal S
BIBINF Norway, Oslo, Norwegian Building Research Institute, 1990, 7pp, 2 refs. #DATE 00:00:1990 in English
ABSTRACT Air infiltration in Norwegian buildings has been an unknown parameter. This paper is based on results from measurements in nine different buildings in Norway. The measured parameters have been: - infiltration,
envelope, - air humidity and temperatures on the inside and outside of the building. The infiltration has been measured continuously with tracer gas using the constant concentration method. In addition air tightness measurements and thermography have been carried out toestablish the dimensions and location of the major leaks. In buildings with mechanical ventilation systems, the flow rates through the inlets and outlets have been measured. The results from the measurements show ahigher infiltration rate than expected. The two houses described in this paper show, without occupancy, an infiltration rate of 0,7 ach.
#NO 3878 The estimation of concentration histories in dwellings in unsteady conditions.
AUTHOR Siren K, Helenius T
BIBINF Norway, Oslo, Norsk VVS, Roomvent 90 proceedings, 13-15 June, 1990, paper 59, 14pp, 8 figs, 2 tabs, 6 refs. #DATE 00:06:1990 in English
ABSTRACT The aim of the study was to determine to what extent it is theoretically possible to estimate the concentration histories in a dwelling when different kinds of disturbances affect the air flows. Thedwelling contained seven rooms and had a mechanical exhaust ventilation system. Tracer gas methods were used to simulate the contaminant transport and to measure the infiltration air flows. A constant releaseof tracer gas was injected into one of the rooms. Two different disturbances were applied. First the location of the exhaust was changed. Secondly a window was opened and closed. The division of the system into six or eight zones affected the calculated concentrations considerably. The mixing of the air was usually quite effective in theindividual rooms and no division into several zones was needed. Opening the window caused cold air from outside to sink to the floor. The mixing of the cold air was very poor. For this reason the calculation failed to some extent, because it used the approximation of perfect and instantaneous mixing. The calculation procedure does, however, have potential for development.
KEYWORDS mechanical ventilation, calculation techniques, tracer gas
#NO 4668 Three-dimensional analysis of airflow pattern and contaminant dispersion in a ventilated two-zone enclosure.
AUTHOR Haghighat F, Wang J C Y, Jiang Z
BIBINF USA, ASHRAE Transactions, Vol 96, Part 1, 1990, pp 831-839, 7 figs, refs. #DATE 00:00:1990 in English
ABSTRACT The pattern of an isothermal airflow caused by infiltration and ventilation in a three-dimensional, two-zone enclosure is investigated by numerical simulation. The two zones are separated by a partition with a door opening. Two types of boundary condition for air supply are considered: (1) the outside air uniformly infiltrates through an end-wall into the enclosure and leaves through a ceiling-mounted exhaust opening; and (2) the ventilation air flows into the enclosure through a rectangular supply opening near the floor on one of the end-walls and leaves the enclosure through the exhaust opening. For each type of boundary condition, two different exhaust opening locations, each with three door positions, are studied. Contaminant concentration distributions for different cases are also presented to illustrate the influences of the flow pattern on the removal of the contaminant generated in one of the two zones. The results show that the location of the door not only guides the direction of the air movement but also affects the strength of the air circulation in the downstream zone,while the upstream zone is less affected by the door position.
KEYWORDS air flow, contaminant, numerical modelling
#NO 5621 Control of exposure to diesel exhaust emissions in fire stations.
AUTHOR Levitsky M, Noonan J, Malik O P, Kwok S T, Vogt H
BIBINF USA, Ashrae, "IAQ 91 Healthy Buildings", proceedings of a conference held September 4-8, 1991, Washington, DC, pp 249-256, 6 figs, 4 tabs, refs. #DATE 00:09:1991 in English
ABSTRACT Firefighters are potentially exposed to diesel exhaust emissions inside fire stations when vehicles start up or return to the station. A survey of 23 Ontario fire stations was conducted toassess the effectiveness of station design and ventilation measures in controlling the concentration of exhaust costituents in living areas. Methods consisted of walk-through surveys, smoke tube tests, and monitoring of changes in concentrations of carbon dioxide and carbon monoxide, used as indicators of contamination by exhaust constituents. Control measures evaluated included structural barriers, natural and mechanical ventilation, and pole hole location. Of the controls examined, the most effective was mechanical tailpipe exhaust. Other effective measures included enclosure of pole holes, general mechanical exhaust on the apparatus floor, natural ventilation, and maintenance of positive pressure in living areas.
KEYWORDS pollutant, toxic gas
#NO 5658 Residential kitchen ventilation- a guide for the specifying engineer.
AUTHOR Wolbrink D W, Sarnosky J R
BIBINF USA, Ashrae, Transactions, Vol 98, Part 1, 1992, 12pp, 11 figs, refs. #DATE 00;00:1992 in English
ABSTRACT The evolution of residential kitchen ventilation is examined and the importance of kitchen range hoods in today's ventilation systems is reviewed as an aid to the specifying engineer. Home cooking produces liquid and solid particles, odors, airborne moisture, heat, and sometimes gas combustion products. How the residential range hood handles these problems is revealed, and the results of various testing programs are given. The proper application of range hoods relative to sizing, room location, and proper ductwork is discussed. The rating methods and standards for hoods are explained and related to real life. The issues of range hood noise and energy conservation are reviewed and answers are provided on how to handle these issues. Current standards and codes dealing with kitchen ventilation are reviewed. The future of kitchen ventilation in home construction is predicted and discussed.
KEYWORDS kitchen, ventilation system, exhaust hood
#NO 5710 The effect of air inlet location on the ventilation of an auditorium.
AUTHOR Vazquez B, Samano D, Yianneskis M
BIBINF UK, London, Institution of Mechanical Engineers, paper from a conference "Computational fluid dynamics - tool or toy?" held 26 November 1991, pp 57-66, 8 figs, 1 tab, 10 refs. #DATE 26:11: 1991 in English
ABSTRACT A numerical study of the ventilation patterns inside an auditorium of the University of Mexico was performed. A general computer program was used to solve the conservation equations of mass, momentum and energy. Simulations of the two-dimensional heat transfer and fluid flow processes within a cross-section of the auditorium were carried out. Data were obtained in the form of air velocity and temperature distributions. Several cases were studied to investigate the effect of the variation of geometrical characteristics of the auditorium; results are presented for different locations of the air inlets on the auditorium walls. The location of the inlets was found to affect significantly the flow pattern and temperature field and thus to influence directly the thermal comfort conditions inside the auditorium. The heat generated by the occupants, the effect of weather conditions on the temperature of the walls and on the incoming air stream and the operation of the ventilation fans were all modelled and/or accounted for and the location of the air inlets on the auditorium walls which provides the optimum thermal comfort conditions for the auditorium occupants was determined.
KEYWORDS air inlets, auditorium, numerical modelling, ventilation system, heat transfer, fan, thermal comfort
#NO 5793 Thermal comfort and indoor air quality in a partitioned enclosure under mixed convection.
AUTHOR Jiang Z, Haghighat F, Wang J C Y
BIBINF UK, Building and Environment, Vol 27, No 1, 1992, pp 77-84, 9 figs, 3 tabs, 10 refs. #DATE 00:00:1992 in English
ABSTRACT The airflow pattern, temperature distribution, and percentage of dissatisfied people in a two-zone enclosure with mixed convection conditions are investigated by numerical simulation. The enclosure is divided by a partition into two zones, A and B, with a door opening connection. A ventilation supply is located on the end-wall of zone A, and an exhaust opening is on the ceiling in zone B. The East wall is assumed to be exposed to sunshine which is modeled by a 300 W constant heat flux. A computer in zone B is simulated by combining a point contaminant source with a point heat source. The effects of door location on flow properties and thermal comfort are examined by placing thedoor opening at three different positions. The results indicate that temperature is quite uniform for the most part throughout the enclosure, except in the region near the floor in zone B; that the PD in most areas is less than 10%; and that average concentrations in zones A and B are at their lowest value when the door is in the middle of the partition, and are not sensitive to the supply air temperature.
KEYWORDS thermal comfort, indoor air quality, convection
#NO 5914 A CFD analysis of ventilation effectiveness in a partitioned room.
AUTHOR Haghighat F, Zheng Jiang, Wang J
BIBINF Denmark, Indoor Air, No 4, 1991, pp 606-615, 9 figs, 2 tabs, refs. #DATE 00:00:1991 in English
ABSTRACT A numerical model has been developed to investigate the contaminant removal and air freshness in a ventilated two-zone enclosure. The average contaminants and the distributions of air age in each zone under variable positions of door, supply and exhaust are compared. Thecorrelation between the average contaminants and each of the main parameters, such as door location, supply and exhaust positions etc., are presented, and the average air ages in both zones are illustrated against door position. It is found that the average air age in the upstream zone is less affected by the door position than that in the downstream zone, and that the door position near the side-walls seems to give better air circulation. It is also concluded that the supply and door positions affect the concentration in the upstream zone significantly, while the exhaust location does not seem to influence the average concentration in either the upstream or the downstream zone.
KEYWORDS computational fluid dynamics, ventilation effectiveness, numerical modelling, door
#NO 5915 Ventilation efficiency.
AUTHOR Rask D R, Woods J E, Sun J
BIBINF USA, Building Systems: Room Air and Air Contaminant Distribution, Ashrae 1989 being proceedings of a Conference held at University of Illinois, Urbana - Champaign, Dec 1988, pp 250-253, 5 figs, 1 tab, refs. #DATE 00:00:1989 in English
ABSTRACT Ventilation efficiency, as defined here, is the percentage of outdoor air provided by the HVAC system that ventilates the occupied space. Knowledge of ventilation efficiency is important in diagnosing indoor air quality problems and in designing spaces capable of providing acceptable indoor air quality in an energy-efficient manner. Poor ventilation efficiencies can lead to the local buildup of contaminants that may affect the health or comfort of the occupants. Investigation of ventilation efficiencies in a building, therefore, becomes a usefulprocedure for evaluating the performance of a building's HVAC systems. A relatively easy, repeatable method is presented to evaluate the ability of air distribution systems to provide the required levels of ventilation air to a building's occupants. Equations to calculate ventilation efficiencies are presented, and a measuring procedure is described whereby ventilation efficiencies can be determined experimentally. The experimental technique can be performed without having to manipulate the HVAC system or building. As examples of this procedure, results are presented for three different types of systems: (1) a 100% outdoor air supply system with ceiling supply air outlets and low-sidewall return air inlets, (2) a fractionally recirculated system with ceiling diffusers and ceiling return inlets, and (3) a heat pump system with the outdoor air being introduced to the space of the ceiling plenum. Results show substantially different ventilation efficiencies, and the poorer ventilation efficiency was attributed to the combined effects of diffuser type, air velocity at the diffuser, and location of the return air grille with respect to the diffuser. Another factor was that air was short-circuiting in the supply and return air ducts and completely by passing the room in one instance. We conclude from these results that it is practical to determine the performance of ventilation systems under actual occupied conditions.
KEYWORDS ventilation efficiency, outdoor air, indoor air quality, ventilation system
#NO 6073 A study on ventilation of the kitchen with a range hood fan.
AUTHOR Gotoh N, Ohira N, Fusegi T, Sakurai T, Omori T
BIBINF Japan, Society of Heating, Air Conditioning and Sanitary Engineers of Japan, 1992, proceedings of the International Symposium on Room Air Convection and Ventilation Effectiveness - ISRACVE, held at the University of Tokyo, 22-24 July, 1992, pp 564-569. #DATE 22:07:1992 in English
ABSTRACT Experimental measurements and numerical simulations are conducted to investigate effective ventilation of a kitchen equipped with a range hood fan. A realistic full-size model kitchen is constructed with which a tracer gas technique is employed to study effects of the location of a single air inlet and the flow rate of the supplied air on the ventilation efficiency of the kitchen fan.Furthermore, flow visualisation experiments using a 1/4 scale model kitchen and numerical simulations are performed to capture flow features in the kitchen. it is found that when the mechanically supplied air interferes with the buoyant exhaust upflow, the ventilation efficiency is affected significantly.
KEYWORDS Ventilation Efficiency, collection efficiency, ventilation in a kitchen, mechanical air supply, tracer gas technique
#NO 6107 The high rise: trends and developments in smoke control.
AUTHOR Paul R V
BIBINF USA, Ashrae Journal, September 1984, pp 28-30. #DATE 00:09:1984 in English
ABSTRACT Describes trends and developments in smoke control in high rise buildings, considering features such as mechanical exhaust, smoke dampers, air leakages through dampers, damper controls, protection of control circuits, location of pressurisation fans, smoke shaft discharge location, below-grade floors, and maintenance.
KEYWORDS smoke control, high rise building
#NO 6385 A CFD analysis of ventilation effectiveness in a partitioned room.
AUTHOR Haghighat F, Jiang Z, Wang J
BIBINF Denmark, Indoor Air, No 4, 1991, pp 606-615, 9 figs, refs. #DATE 00:00:1991 in English
ABSTRACT A numerical model has been developed to investigate the contaminant removal and air freshness in a ventilated two-zone enclosure. The average contaminants and the distributions of air age in each zone under variable positions of door, supply andexhaust are compared. The correlation between the average contaminants and each of the main parameters, such as door location, supply and exhaust positions etc., are presented, and the average air ages in both zones are illustrated against door position. It is found that the average air age in the upstream zone is less affected by the door position than that in the downstream zone, and that the door position near the side-walls seems to give better air circulation. It is also concluded that the supply and door positions affect the concentration in the upstream zone significantly, while the exhaust location does not seem to influence the average concentration in either the upstream or the downstream zone.
KEYWORDS computational fluid dynamics, ventilation effectiveness, numerical modelling
#NO 6413 Control of airborne particle concentration and draught risk in an operating room.
AUTHOR Chen Q, Jiang Z, Moser A
BIBINF Denmark, Indoor Air, No 2, 1992, pp 154-167, 8 figs, 1 tab, refs. #DATE 00:00:1992 in English
ABSTRACT The influence of location of airborne particle source, ventilation rate, air inlet size, supply air velocity, air outlet location, and heat source on the distributions of airborne particle concentration and draught risk in an operating room is investigated. The investigation is carried out by using a flow program with the k-e model of turbulence. Based on a standard case, five cases, each with one changed parameter, are computed, and the detailed field distributions of air velocity,temperature, airborne particle concentration, and draught risk are presented. The parametric study concludes that, for a better air quality and thermal comfort, it is desirable to use a higher inflow rate, a larger inlet area, and a uniform velocity profile of supply air. Outlet location and heat source have little influence on the distributions of the particle concentration in the room. It has also been found that the distributions of particle concentration in the recirculating zone are very sensitive to the location of the particle sources.
KEYWORDS particle, pollutant, draughts, operating theatre, human comfort
#NO 6521 Automobile passenger compartment ventilation.
AUTHOR Helnsohn R J, O'Donnell P E W R, Jionqin Tao
BIBINF USA, ASHRAE Transactions, Vol 99, Pt 1, 1993, 12pp, 12 figs, 4 tabs, refs. #DATE 00:00:1993 in English
ABSTRACT A sequential box model (SBM) is proposed that predicts the instantaneous contaminant concentration at arbitrary points in athree-dimensional enclosure when the contaminant generation rate varies with time and location. The method can also accommodate time-varying ventilation flow rates and contaminant concentrations in the makeup air supply. The method is used to predict the passenger breathing zone concentrations of a) cigarette smoke, when passengers smoke following some describable schedule, and b) carbon monoxide, when the exhaust from a vehicle is drawn into the air intake of the vehicle behind it. The critical parameter affecting the accuracy of the method is the selection of exchange coefficients that describe thetransport of air and contaminants from one box to another.
KEYWORDS carbon monoxide, tobacco smoke, occupant reaction
#NO 7013 Ventilation efficiency measurements in a test chamber with different ventilation and cooling systems.
AUTHOR Roulet C-A, Cretton P, Kofoed P
BIBINF UK, Air Infiltration and Ventilation Centre, 14th AIVC Conference, "Energy Impact of Ventilation and Air Infiltration", held Copenhagen, Denmark, 21-23 September 1993, proceedings, pp73-80. #DATE 21:09:1993 in English
ABSTRACT Cooling ceilings are more and more proposed, in order to eliminate excess heat in office buildings without consuming much energy in air transport. On the other hand, piston ventilation is proposed to efficiently eliminate contaminants. These twosystems may however interact and experiments were planned to look at these interactions. Measurements of the age of air and air change efficiency were performed, together with more classical temperature and air velocity measurements, on various ventilation systems installed in the test chamber of SulzerInfra, in Winterthur. The test chamber was arranged to simulatean office room, with heat generated from computers andoccupants. Moreover, the contaminants from one occupant were simulated with a tracer gas and the contaminant removal effectiveness was measured at various locations in the room. Six different series of measurements were performed with displacement ventilation, with two types of cooling ceilings. Two more tests were performed with mixing ventilation, using two different inlet grilles. As expected, both mixing system, measured with the continuous cooling ceiling "on", reach nearly complete mixing, hence an air change efficiency close to 50% and a uniform contaminant removal effectiveness close to 1. Displacement ventilation systems showed a larger air change efficiency in most cases. However, the cooling ceiling counteracts the displacement and important mixing is observed when it is on, mainly if the air flow rate is lower than 5 volumes per hour. A test without cooling showed a strong displacement effect, the local mean age at every occupant location being lower than the room mean age. Except in this particular test, the contaminant removal effectiveness is generally about 1. It should be noted that, for these latter measurements, the contaminant source was not far from the inlet grilles, which represents the worst possible case. It is also shown that systems with a high air change efficiency do not necessarily provide fresh air to the occupants.
KEYWORDS ventilation efficiency, test chamber, cooling, ventilation system
#NO 7138 HVAC system provisions to minimize the spread of tuberculosis bacteria.
AUTHOR Rousseau C P, Rhodes W W
BIBINF USA, Ashrae Transactions, 1993, Vol 99, Part 2, Preprint, 4pp, 1 fig, refs. #DATE 00:07:1993 in English
ABSTRACT This paper discusses the ability of the HVAC system to assist in maximizing the containment of the tuberculosis bacterium. The methods discussed will include ventilation, types and location of special filters, room pressure relationships between infected and non infected and contaminated and non contaminated spaces, exhaust system arrangements, and room air distribution approaches. The "CDC Guidelines for Preventing the Transmission of Tuberculosis in Health-Care Settings, with Special Focus on HIV-related Issues" is the only document available that addresses specific HVAC system recommendations in detail. This paper discusses these provisions from a practical standpoint and in greater detail. The goal is to provide health care HVAC system designers with additional information to be considered by HVAC system designers and suggestions to allow them to better assist clients with tuberculosis control and to suggestadditional information to be considered by HVAC system designers during their design of medical facilities.
KEYWORDS disease, air conditioning, hospital, ventilation system
#NO 7156 Development of high-efficiency air cleaners for grilling and deep-frying operations.
AUTHOR Knapp J N, Cheney W A
BIBINF USA, Ashrae Transactions, 1993, Vol 99, Part 2, Preprint, 5pp, 5 figs. #DATE 00:07:1993 in English
ABSTRACT Removal of grease from commercial deep-frying and grilling exhaust airstreams is a difficult challenge. Fire codes and the requirement to not allow a deterioration of the capture air necessary to draw contaminants into the exhaust duct are not compatible with typical high-efficiency air cleaner systems. By selecting a location near the grease source and using an electrostatic precipitator (ESP) modified for the application, a leading fast food restaurant company has successfully controlled particulate emissions. In the long ductwork exhausts common inEurope, this has resulted in large savings in duct-cleaning costs while cleaning the exhaust airstream. The system has been proved in more than 3,000 units with installations beginning more than 10 years ago.
KEYWORDS air cleaning, kitchen, commercial building, exhaust hood
#NO 7226 Ventilation of an auditorium and its effect on wall heat transfer
AUTHOR Vazquez B; Samano D; Yianneskis M
BIBINF UK, CIBSE, proceedings of CLIMA 2000, 1-3 November 1993, Queen Elizabeth II Conference Centre, London, 1993, paper no. 325.
ABSTRACT A numerical study of the forced convection flows across a two-dimensional cross-section of an auditorium was performed. The aim of the study was to determine the flow patterns and temperature fields produced by theventilation and assess their effect on the wall heat transfer and the thermal comfort conditions inside the auditorium. A Computational Fluid Dynamics program was used to solve the conservation equations for mass, momentum and energy; the k-î model was used for the representation of turbulence. The flow rate through the outlet was varied to obtain Reynolds numbers from 1,000 to 150,000. In all cases calculated the body heat generated by the occupants of the auditorium was modelled. Data were obtained in the form of distributions of air velocity, turbulence kinetic energy and temperature within the auditorium and of heat transfer coefficient on the walls and seats. The effects of the location of the air inlets, of the size of the air outlet(s) and of the outlet of velocity on the flow patterns were investigated.
KEYWORDS ventilation auditoria walls heat_flow convection thermal_comfort computer_programs calculating models flow_rate Reynolds_number occupants_providing_heat air_inlets vents air_flow
#NO 7277 Numerical calculation of room air motion - part 1: Maths, Physics, and CFD Modeling.
AUTHOR Baker A J, Williams P T, Kelso R M.
BIBINF USA, Ashrae Transactions, Vol 100, Pt 1, 1994, (preprint), 17pp, 2 figs, refs. #DATE 00:00:1994 in English
ABSTRACT Obtaining an accurate understanding of the distribution characteristics of indoor air systems with respect to volume, velocity, and position within a space is crucial to the development of control measures. The effectiveness of ventilation systems is directly related to the manner in which supply air is circulated within an occupied zone.This pattern of air circulation, hence mixing, is in turninfluenced by the location of air supply outlets, windows, room geometry and exhausts, and interior furnishings, as well as by building heating and cooling systems. This three-part paper documents research completed on the topical aspects of computational fluid dynamics (CFD) associated with the room air motion problem class. The mathematical, hence computational, requirement is attainment of accurate approximate solutions to theincompressible, three-dimensional Reynolds-averaged Navier-Stokes equations for thermal flows in room geometries. Part 1 addresses the math/physics issues of CFD modeling and documents available and newly established CFD theoretical foundations. Part 2 documents performance assessments for a newly derived CFD algorithm, with validations for benchmark problems with known comparative solutions pertinent to the room air motion problem class. Part 3 presents and documents detailed results of a CFD computational experiment for flowfield prediction in athree-dimensional room geometry for a range of simulated turbulence levels, with detailed comparisons with available full-scale laboratory experimental data.
KEYWORDS air movement, computational fluid dynamics, modelling.
#NO 7477 A numerical and experimental study of local exhaust capture efficiency.
AUTHOR Madsen U, Breum N O, Nielsen P V
BIBINF UK, Ann. Occup. Hyg. Vol 37, No. 6, 1993, pp 593-605, 6 figs, 4 tabs, refs.#DATE 00:00:1993 in English
ABSTRACT Direct capture efficiency of a local exhaust system is defined by introducing an imaginary control box surrounding the contaminant source and the exhaust opening. The imaginary box makes it possible to distinguish between contaminants directly captured and those that escape. Two methods for estimation of direct capture efficiency are given; (1) a numerical method based on the time-averaged Navier-Stokes equations for turbulent flows; and (2) a field method based on a representative background concentration. Direct capture efficiency is sensitive to the size of the control box, whereas its location is less important for the case studied. The choice of sampling strategy to obtain a representative background concentration is essential as substantial differences on direct capture efficiency are found. Recommendations are given.
KEYWORDS Exhaust, numerical modelling.
#NO 7831 Indoor/outdoor levels of pollutants
AUTHOR Peterson F
BIBINF Sweden, Stockholm, Royal Institute of Technology Dept of Heating and Ventilation, publication 'Dust Analysis' no 1;1991, 80pp#DATE 00:00:1991 in English
ABSTRACT The level of pollutant gases indoors is partly determined by the level outdoors. This is significant in as much as the outdoor pollutant levels and their routes of spread set the limits for the amount of cleaning the air needs and also the purification method. It is becoming more common to avoid window airing in larger cities for this reason. The ventilation takes place with fans. But even here the location of the air intake and the degree of purification is important for the purity of the indoor air.The above phenomena have been dealt with in a literature study. It can be stated from this that the purity of the indoor air largely follows that of the outdoor air, and that the indoor pollutant sources are small compared to the pollutants transported via various supply air routes.One outcome of the investigation is that the location of the air intake is often more critical than was previously thought. Another is that the supply air needs to be purified more than it is now. The matter has been dealt with practically in some small studies, which have shown that replacing coarse filters with fine filters is an effective way of bringing about improvements to the sick building syndrome.
KEYWORDS pollutant, outdoor air, fan, air inlets
#NO 7913 Reentry of Radon from mitigation system outlets
AUTHOR Yuill G K, Coughlin R J
BIBINF USA, ASHRAE Transactions, Vol 100, Pt 2, 1994, (preprint), 8pp, 3 figs, 4 tabs, refs. #DATE 00:00:1994 in English
ABSTRACT Some radon mitigation systems draw air with a high radon concentration from under the basement floors of houses and exhaust it outdoors. The objective of this project was tomeasure the reentry rates of radon released at roof level and at ground level near a house to determine whether exhaust above the roof is necessary. This was done by using a portable mockup of a radon mitigation system exhaust, with sulfur hexafluoride (SF6) as a tracer gas. The roof level exhaust produced maximum indoor sulfur hexafluoride concentrations that were significantly lower than those from the ground level exhaust. This suggests that the better radon discharge location is on the roof of a house.
KEYWORDS radon, basement, roof, tracer gas
#NO 7914 Wind tunnel modeling of diesel odors for fresh air intake design
AUTHOR Ratcliff M A, Petersen R L, Cochran B C
BIBINF USA, ASHRAE Transactions, Vol 100, Pt 2, 1994, (preprint), 9pp, 11 figs, refs. #DATE 00:00:1994 in English
ABSTRACT Odors from idling diesel tanks at loading docks and from emergency diesel generators often lead to complaints. Improper layout of the buildings the diesel source locations and the building fresh air intake locations add to the situation. To evaluate odor problems and possible alternative air intake locations, wind tunnel modeling is used to predict the dispersion of the diesel exhaust within the complex airflow patterns around buildings. Standard numerical models do not work in the immediate vicinity of buildings especially for ground-level sources. The wind climate of the site and odor objection data from the literature are also used. Four case studies are presented that illustrate the analytical procedure and typical results. The open face of a building is preferred location for diesel sources rather than within U-shaped and L-shaped building enclosures
KEYWORDS wind tunnel, odour, outdoor air
#NO 7963 The role of infiltration for indoor air quality
AUTHOR Baranowski A
BIBINF UK, Air Infiltration and Ventilation Centre, 1994, "The Role of Ventilation", proceedings of 15th AIVC Conference, held Buxton, UK, 27-30 September 1994, Volume 1, pp133-140.
ABSTRACT Multifamily buildings with natural ventilation are still being built and exploited. Such buildings are often equipped with individual gas-fired water heaters located in windowless bathrooms. It implicates the possibilities of improper gas exhaust as a result of the decrease of infiltration, what could be sometimes even harmful for the occupants' health. Based on the numerical simulations, analysis of ventilating air flows in typicalmultifamily dwelling house will be carried out. it will be shown that effectiveness of natural ventilation in particular flats depends not only on the active factors determining infiltration phenomenon (like wind and temperature difference) but is also strongly connected wit flat location inside the complex structure of a building.
KEYWORDS (infiltration, indoor air quality, natural ventilation, combustion product, numerical simulation)
#NO 8344 Location of air intakes to buildings situated in urban environments.
AUTHOR Krueger Ulf.
BIBINF Poland, Silesian Technical University, 1994, proceedings of Roomvent '94: Air Distribution in Rooms, Fourth International Conference, held Krakow, Poland, June 15-17, 1994, Volume 2, pp 373-388.
ABSTRACT In urban environments the locations of air intakes in relation to outdoor pollutant sources are important. A significant parameter is where the building is situated in relation to streets with heavy traffic. The wind direction and velocity, street geometry and building construction are also of importance for the concentrations of traffic-related pollutants at street side and backyard of a building, especially when the building is located adjacent to a street on one side. In this study carbon monoxide, CO was used as an indicator of traffic related sources. The measurements show that monitoring periods of at least one week are needed to get reliable results and that climatic conditions influence the concentration difference of traffic related pollutants between street side and backyard of a building. When a mechanical exhaust system is used, the outdoor air is normally supplied to the rooms through the facades. The result of this arrangement could be that the indoor air will be more contaminated than when using a balanced system with the air intakes placed at the back of the building or on the roof. However, if the building is not close to busy streets, the mechanical exhaust system could be a good solution from the air quality point of view.
KEYWORDS air inlets, wind direction, carbon monoxide, outdoor air
#NO 8424 Computer simulation of ventilation strategies for maintaining an acceptable indoor air quality in office buildings
AUTHOR Said M Nade A, Shaw C Y, Plett E G, Vaculik F.
BIBINF USA, ASHRAE, 1995, proceedings of ASHRAE Centennial Conference, held 28 January - 1 February 1995, Chicago, USA, 8pp, 11 figs, 2 tabs, refs.
ABSTRACT This paper evaluates the effects of various ventilation strategies on contaminant distribution in a 22-storey office building for two events; 1. a partial renovation event, when a part of an occupied building is renovated, and 2. a scheduled shutdown event, when the HVAC systems are shut down during a holiday or a weekend A multizone air and contaminant flow model was used to predict contaminant distribution in a 22-storey office building. The model calculates pressures, airflows, and the time-varying contaminant concentration in the zones of a tall building. For a partial renovation event, the ventilation strategies included venting the renovated zone using window(s), a stairwell, a smoke control shaft, and mechanical exhaust. For a scheduled shutdown event, typical building operation was assumed with no specific source zone in the building. The objective of the computations was to determine the required start-up time of the HVAC system to diminish accumulated pollutant concentration in the building following a scheduled shutdown. Computations were conducted for winter, spring, and summer outdoor conditions. The effectiveness of various ventilation strategies for minimizing the spread of the contaminant from the renovated zone to the surrounding areas depends on the location of the renovated zone with respect to the neutral pressure plane in the building. For the building used in the study, based on an outdoor air supply rate of 0.94 ACH, a four-hour start-up of the HVAC operation is adequate to diminish accumulated pollutant concentration in the building after a scheduled shutdown.
KEYWORDS simulation, ventilation strategy, indoor air quality, office building
#NO 8434 Automobile passenger compartment ventilation.
AUTHOR Heinsohn R J, O'Donnel W R, Tao J
BIBINF Ashrae Trans, 1993, Vol 99 part 1, paper no. 3669, pp 476-487, 12 figs, 4 tabs, refs.
ABSTRACT A sequential box model (SBM) is proposed that predicts the instantaneous contaminant concentration at arbitrary points in a three-dimensional enclosure when the contaminant generation rate varies with time and location. The method can also accommodate time-varying ventilation flow rates and contaminant concentrations in the makeup air supply. The method is used to predict the passenger breathing zone concentrations of (a) cigarette smoke, when passengers smoke following some describable schedule, and (b) carbon monoxide, when the exhaust from a vehicle is drawn into the air intake of the vehicle behind it. The critical parameter affecting the accuracy of the method is the selection of exchange coefficients that describe the transport of air and contaminants from one box to another.
KEYWORDS modelling, pollutant, air flow
#NO 8444 A CFD analysis of effects of vent location on pollutant concentration in rooms.
AUTHOR Chaturvedi S K, Mohieldin T O
BIBINF Building systems - room air contaminant distribution, 5-8 December 1988, University of Illinois, Ashrae 1989, Ed Christianson L L, pp 158-160, 8 figs, 4 refs.
ABSTRACT The turbulent air motion and the diffusion of carbon dioxide from a line source located on the floor of a room are computed numerically by solving the governing equations for mass, momentum, turbulent kinetic energy, dissipation, and concentration. A well-known finite volume procedure is employed to discretize the partial velocity field and concentration contours are presented and compared for three different intake and exhaust vent geometries.
KEYWORDS CFD, pollutant
#NO 8450 Dilution of exhaust gases from building surface vents.
AUTHOR Wilson D J
BIBINF DT (ASHRAE Trans.) 1977, Part 1, 168-176, 10 figs, 5 refs. 697.982
ABSTRACT Notes importance for designer to be able to estimate chance of wind around a building recirculating any toxic or corrosive gases, vapours or odours to an air intake or to ground level. Treats experiments on 2 building models of medium and high-rise structures, using flow visualisation and wind tunnel measurement of exhaust gas dilution to determine whether dilution factors for vents on vertical sides of a building can be estimated using same equation developed for roof vents. Provides and discusses results. Finds use of equation to be generally satisfactory, regardless of vent location.
KEYWORDS Exhaust gases, buildings, vents, winds, recirculating, toxic gases, gases, corrosion, vapours, odour, wind tunnels, factors, diluting, air flow visualisation
#NO 8500 Dispersion in jets from short stacks.
AUTHOR Hallitsky J.
BIBINF USA, Ashrae Winter Meeting, January 1995, 21 pp, 19 figs, refs.
ABSTRACT When a building exhaust stack and a fresh air intake are located on the same roof and the stack has sufficient volume flow and emission velocity to create a free jet in a crosswind, an accurate calculation of the exhaust concentration at the intake requires a model of the initial plume region. EPA models provide no guidance in this regard since they apply to receptors located at distances greater than several building heights downwind of the stack, for which a crude virtual source approximation is adequate. The Halitsky Transverse Jet Plume model fills this gap. It was developed in two stages, referred to herein as the 1966 model and the 1989 model. The 1966 model employed empirical equations based on wind tunnel test observations to describe the growth of the plume from its origin at the stack top, through the jet region where plume velocities differ from the free wind velocity, and then in the simple plume region where dispersion is controlled by wind properties alone. This radially symmetric model used a longitudinal coordinate distance s measured along the plume centreline, a radial coordinate distance r perpendicular to the centreline, and different plume boundary expansion rates in three plume regimes. The curvilinear coordinate s was used because no plume rise equation had yet gained general acceptance, and conversion to an x,y,z system was dependent on the centreline shape. The 1989 model is an updated, simplified version of the 1966 model. It uses x,y,z coordinates, the Briggs neutrally buoyant plume rise equation, and a wind turbulence factor based on the Pasquill-Gifford stability classification scheme. The jet region is not modeled explicitly because it was found from experience that fresh air intakes would rarely be exposed to it. The characteristics of the jet region may be retrieved by use of the equations in the 1966 model. A key point of the 1989 model is the specification of the plume properties at Station 2 located at the end of the jet region (start of the simple plume region). Here, the radial concentration distribution is converted from triangular in the jet region to Gaussian in the simple plume region. The values of x2, z2, and o2 may be used to calculate a virtual source location or to serve as a starting cross section for downwind expansion of the simple plume.
KEYWORDS Stack, air inlets, wind effects, air flow.
#NO 8532 The effects of glass doors on masonry fireplace spillage and surface temperatures
AUTHOR Honeycutt D J, Jaasma D R, Stern C H
BIBINF Canada Mortgage and Housing Corporation, October 27, 1994, 20 pp, 18 figs, 3 tabs, 3 refs.
ABSTRACT A single masonry fireplace was retrofitted with glass doors to examine their impact on fireplace safety. Two test series were performed. The first examined the effect glass doors had on fireplace spillage. The second examined the effect glass doors had on fireplace temperatures. The first series of tests was composed of fifteen spillage tests in which the door air leakiness and external air supply opening were varied. For these tests a chamber designed to maintain a constant level of depressurization was constructed around the fireplace to allow simulation of house depressurization. Fireplace spillage was monitored by measuring carbon monoxide concentrations in air exhausted from the spillage chamber. The second series consisted of nine fire safety tests. Temperatures were measured on both the interior and exterior of the fireplace. Exterior temperatures were measured at buried member, exposed surface, and glass door locations. Interior temperatures were measured on the firebox walls and in the flue gas. The influence of the glass doors was altered for each test by adjusting the leakiness, the leak location, or the length of time the doors were open. Spillage was reduced substantially with the use of glass doors. However, tighter glass doors did not always give further reductions in spillage. Increasing the size of the external air supply also did not consistently reduce spillage. Further testing would be necessary to clarify the dependence of spillage on door leakiness and air supply opening. Buried member and glass door temperatures measured during closed-door tests were only moderately higher than those reached during open-then-closed-door tests. For the fireplace tested, these elevated temperatures did not appear to be a safety hazard. For this fireplace, the use of glass doors reduced spillage with only modest increases in temperature. While this conclusion may be representative, it should not be generalized without testing additional fireplaces.
KEYWORDS spillage, masonry fireplace, house depressurization, fire safety, glass doors
#NO 8585 Performance of a laboratory fume hood with an air curtain
AUTHOR Peng S-H, Peterson F, Qiang-Min L.
BIBINF Sweden, Proceedings of the 4th International Symposium on Ventilation for Contaminant Control, Ventilation '94, held in Stockholm, September 5-9, 1994, Arbetsmiljoinstitutet, 1994:18, Part 1, pp 270-275.
ABSTRACT An important parameter for the performance of laboratory fume hoods with an air curtain is the Auxiliary Air Ratio (AAR), defined as the ratio between the flow of the air curtain and the total exhaust flow of the hood. The flow field around the hood was numerically simulated by the k-e turbulence model. The relationships between the optimum AAR and the width of the air curtain opening B, and between the optimum AAR and the location of the opening C, were determined by numerical concentration measurements. The optimum value of the AAR increased with increasing values of B and C. The presence of a manikin in front of the hood resulted in air recirculation patterns being formed. These can be successfully reduced by a properly supplied air curtain flow.
KEYWORDS fume hood, air curtain, laboratory, numerical modelling
#NO 8591 Effect of exhaust opening location on dust exposure during powder weighing
AUTHOR Kimmo H, Kulmala I
BIBINF Sweden, Proceedings of the 4th International Symposium on Ventilation for Contaminant Control, Ventilation '94, held in Stockholm, September 5-9, 1994, Arbetsmiljoinstitutet, 1994:18, Part 1, pp 327-332.
ABSTRACT The effects the exhaust opening location and the local supply air have on the worker's exposure were experimentally investigated. Those experiments were conducted in controlled conditions in a test room. In them the worker was simulating manual powder weighing in a workstation equipped with local supply and exhaust ventilation. The results of the experiments showed that the local supply air increases the efficiency of the local exhaust in preventing the worker's exposure. The lowest contaminant source in combination with the local supply air. With this configuration the worker's exposure was 0.06 mg/m3, when it was 45 mg.m3 using dilution ventilation only. The results can be used in designing the control of exposure in manual powder handling.
KEYWORDS exhaust, dust, particle, workplace
#NO 8912 A Quantification of an indoor population by means of air exchange rates and carbon dioxide gas concentrations.
AUTHOR Olcerst R
BIBINF USA, Am. Ind. Hyg. Assoc. J., No Vol 55, No 11, November 1994, pp 1080-1083, 3 figs, 1 tab, 6 refs.
ABSTRACT A technique is presented to extend the utility of commercially available datalogues to provide information on the ventilation effectiveness and air exchange rate of a compartment. An electronic timed sampling valve was used to collect air alternatively from the room exhaust and the breathing zones of occupants. The timed valve provided a data set for each location that was fitted to an exponential one-compartment clearance model. The fitted data were used to calculate air exchange, mean air life, half-life of room air, ventilation effectiveness, and correlation of fit. The technique used ambient carbon dioxide gas concentrations as a natural tracer, or compressed carbon dioxide as a pulse-inject tracer gas.
KEYWORDS carbon dioxide, tracer gas, data logger, ventilation effectiveness
#NO 8996 A technique to use data loggers to measure effective ventilation and air exchange rates by carbon dioxide tracer.
AUTHOR Olcerst R
BIBINF USA, Am. Ind. Hyg. Assoc. J., No 55, September 1994, pp 833-835, 4 figs, 7 refs.
ABSTRACT This paper presents a technique to extend the utility of commercially available data loggers to provide information on the ventilation effectiveness and air exchange rate of a compartment. An electronic times sampling valve was used to collect air alternately from the room exhaust and the breathing zones of occupants. The times valve provided a data set for each location that was fitted to an exponential one-compartment clearance model. The fitted data were used to calculate air exchange, mean air life, half-life of room air, ventilation effectiveness, and correlation of fit. The technique used ambient carbon dioxide gas concentration as a natural tracer, or compressed carbon dioxide as a pulse-inject tracer gas.
KEYWORDS data logger, ventilation effectiveness, air change rate, carbon dioxide, tracer gas
#NO 9045 Temperature and velocity distributions for slot devices.
AUTHOR Kruger U
BIBINF UK, Air Infiltration and Ventilation Centre, 16th AIVC Conference Implementing the results of ventilation research , held Palm Springs, USA, 18 - 22 September, 1995, Proceedings Volume 1, pp 59-68.
ABSTRACT Depending on the demands regarding the size and location of the occupation zone and the need for outdoor air flow rates, different ventilation systems and air supply devices have to be used in different kinds of buildings. The occupation zone in a residential building can be difficult to define, as many different activities can take place. Furthermore the furnishings of the room can change with time. The highest air velocities and the lowest air temperatures in the occupation zone will often occur close to inlet air devices. The importance of the location and selection of inlet air devices is exemplified by studying an air slot device for mainly residential use. The slot device was placed over a window at a height of 2.0 m above floor level. Both measurements and calculations of air velocity and temperatures are presented in the paper. From a thermal comfort point of view the device tested seem to give satisfactory performance only for air flow rates less than 4 l/s. The draught problem will increase with lower inlet temperatures. It is also shown that the internal heating in a device can be important with regard to thermal comfort. The factors that influence the relationship between outdoor and supply temperature are also discussed.
KEYWORDS supply vent, outdoor air, air velocity, temperature
#NO 9187 Using particle trajectories to evaluate indoor air quality.
AUTHOR Chung K C, Lee C Y
BIBINF Indoor Environ, No 4, 1995, pp 170-176, 6 figs, 16 refs.
ABSTRACT A numerical technique has been developed to predict the path of pollutant particles exhausted by a ventilation system from a control space. A simulated contaminant source located inside an indoor environment was used to investigate the indoor air quality. The proposition explored was that a measure of indoor air quality was the efficiency of a ventilation system which minimized the residence time of polluted particles indoors which in turn could be quantified in terms of the age of individual particles. The age of particles in this study, as a time-dependent parameter, was calculated using a residence time model. Finally, the concentration fields caused by an indoor pollution source and the effects of particle strength and source location in indoor air quality were examined.
KEYWORDS particle, indoor air quality, numerical modelling, pollutant
#NO 9247 Indoor air problems in Asia.
AUTHOR Leslie G B
BIBINF Indoor Environ., No 4, 1995, pp 140-150, 77 refs.
ABSTRACT Respiratory disease and mortality due to indoor air pollution are amongst the greatest environmental threats to health in the developing countries of Asia. Worldwide acute respiratory infection is the cause of death of at least 5 million children under the age of 5 every year. The World Bank has claimed that smoke from biomass fuels resulted in an estimated 4 million deaths annually amongst infants and children. Most of these deaths occur in developing countries. Combustion in its various forms must head the list of pollution sources in Asia. Combustion of various fuels for domestic heating, lighting and cooking comprises the major source of internally generated pollutants and combustion in industrial plants, power generation and transportation is the major cause of externally generated pollutants. The products of pyrolysis and combustion include many compounds with well known adverse health effects. These include gases such as CO, CO2, NOx and SO2, volatile organic compounds such as polynuclear aromatic hydrocarbons and nitrosamines as well as respirable particulates of variable composition. The nature and magnitude of the health risks posed by these materials vary with season, climate location, housing method of ventilation, culture and oscio-economic status. The most important cause of lung cancer in non smokers in Northern Asia is the domestic combustion of smokey coal. Acute carbon monoxide poisoning is common in many Asian countries. Roads traffic exhaust pollution is worse in the major cities of South East Asia than almost anywhere else in the world and this externally generated air pollution forms the indoor air for the urban poor. Despite all these major problems there has been a tendency for international agencies to focus attention and resources on the more trivial problems of indoor air encountered in the affluent countries of the West. Regulatory agencies in Asia have been too frequently persuaded that their problems of indoor air pollution are similar to those in the West and require similar legislation.
KEYWORDS indoor air quality, health, combustion appliance, wood, tobacco smoke
#NO 9547 Design criteria of ventilation for healthy buildings.
AUTHOR Seppanen O
BIBINF Healthy Buildings 95, edited by M Maroni, proceedings of a conference held Milan, Italy, 10-14 September 1995, pp 215-238, 10 figs, 6 tabs, 38 refs.
ABSTRACT The purpose of ventilation is to maintain and improve air quality in a building by removing polluted air and supplying fresh air. In principle, the required ventilation rates for desired air quality can be calculated if the pollution loads, outdoor air quality and requested indoor air quality are known. This method is often referred to as an air quality method in ventilation design. A European prestandard Ventilation for Buildings - Design Criteria for the Indoor Environment outlines such a method. The data for the application of the standard is rapidly accumulating through extensive measurements and is soon available for the general application in ventilation design. Because the data are not yet completed for practical use, additional prescriptive requirements and criteria have to be used in the design of ventilation systems. These criteria include such aspects as the selection of ventilation strategy, ventilation rates, balancing of airflows, ventilation effectiveness, local exhaust systems, cleaning of intake air, location of air intakes, cleanliness of equipment, air recirculation, air tightness, noise control and demand controlled ventilation. The reasoning behind these requirements is presented and discussed in the paper.
KEYWORDS building design, health
#NO 9574 Improvement of thermal comfort and air quality using displacement ventilation systems.
AUTHOR Guntermann K, Plitt U
BIBINF Healthy Buildings 95, edited by M Maroni, proceedings of a conference held Milan, Italy, 10-14 September 1995, pp 1203-1208, 6 figs.
ABSTRACT Displacement ventilation systems in German called Quelluftung become more and more popular and have proved themselves in many different applications in comfort as well as in industrial air conditioning systems. However, there are many uncertainties according to the design of the systems. In a research project the basis and the technical conditions had been worked out. The influence of the air outlet and the heat sources on the temperature and contaminant distribution within the room was investigated. Displacement ventilation introduces supply air into the room at or near floor level and at a temperature lower than that of the ambient room air. The supply air thus fills the room from the floor up, displacing the old air and any contaminants that it carried. Additional buoyancy flows caused by heat sources are overlapping the displacement flow. The buoyancy flow is greater than the displacement and this causes the typical stratification of source flow. There is a layer of supply air near the floor, upwards there is a layer of mixed air, which is primarily influenced by the location and intensity of the heat sources. Above the mixing zone there is another displacement zone up to the ceiling, where the exhaust air is taken. When room ventilation is by displacement, temperature and contaminant concentrations increase with the height of the room. Without any heat sources, this gradient would be uniform. However, in typical rooms, heat sources such as people or equipment should cause convection currents that result in the cleaner air near the floor being forced upward into the breathing zone at a rate higher than the displacement flow. The displacement flow rate should be lower than the convection flow rate because maintaining a low velocity in the supply air prevents drafts from becoming a problem. Displacement ventilation flow rate should ideally remain below 0.2 metres per second.
KEYWORDS thermal comfort, displacement ventilation
#NO 9624 Airflow distributions at floor level in a slot outlet and slot inlet ventilated room.
AUTHOR Wang J, Ogilvie J R
BIBINF USA, Ashrae Transactions, Vol 102, Pt 2, 1996, 12 figs, 8 tabs, refs.
ABSTRACT Air velocities in the occupied zone were measured in a full-size, slot-outlet and slot-inlet ventilated (SOSIV), unoccupied room. The measurements were taken at different room heights with two outlet/inlet locations, five levels of outlet jet momentum, with and without floor heating. the near floor air-flow in the SOSIV room possesses velocity and turbulence profiles similar to those of a fully developed wall jet. The velocity and turbulence profiles measured at the rooms mid-length are similar, with each representing the mirror image of the other. A full model was proposed to predict the floor-level air velocity in the SOSIV room. For a given room aspect ratio and a given outlet/inlet location, the floor-level air velocity can be uniquely determined by the jet momentum ratio under isothermal conditions and is determined by both the jet momentum ratio and the thermal buoyancy under nonisothermal conditions. The outlet and inlet locations and the room aspect ratio can significantly affect the floor-level air velocity. The results can be applied to industrial plants and agricultural buildings.
KEYWORDS air distribution, floor, ventilation system, air velocity
#NO 9671 Thermal comfort in the near-zone of a radiator air device.
AUTHOR Kruger U
BIBINF Indoor Air, No 6, 1996, pp 55-61, 9 figs, 4 tabs, refs.
ABSTRACT The near-zone of an air inlet device is the most critical part of a room as regards fulfillment of the thermal conform demands. An acceptable solution for residential buildings can be to supply the outdoor air through an air device place behind a radiator. Such a device provides a mechanical exhaust system that supplies pre-heated outdoor air. Normally radiator air devices are located below a window and window-sill. To examine the influence of a window-sill placed above an air device, several different positions and breadths of sills were tested. Air velocities, and air temperatures were measured at distances within 0.50m from the device. The measurements show that thermal comfort is strongly dependent on the location of the window-sill in relation to the air device. The degree of turbulence intensity affects the percentage of dissatisfied people due to draught. The velocity measurement system used in this study allows variation of the time constant of the system. When different time constants were used, the measured turbulence intensity varied considerable. Some measurements were carried out with the radiator switched off. In these cases different air velocities were measured, depending on the orientation of the sensors. This seems to be due to the temperature and velocity gradients at the measuring points.
KEYWORDS thermal comfort
#NO 9681 Ventilation and environmental quality in laboratory animal facilities.
AUTHOR Maghirang R G, Riskowski G L, Christianson L L
BIBINF USA, Ashrae Transactions, Vol 102, Pt 2, 1996, [preprint], 1 tab, refs.
ABSTRACT Laboratory animal ventilation systems should be designed to provide acceptable environmental conditions within the room and within cages. This study was conducted to review and evaluate ventilation strategies for improving thermal and air quality conditions in laboratory animal facilities. It has long been recognized that the cage microenvironment can be considerably different from the room macroenvironment. However, most research on laboratory animal ventilation has focused on room conditions. There is limited information regarding ventilation rates, room air distribution, and other factors required to maintain acceptable and uniform environment in all animal cages. Current ventilation guidelines are based largely on room conditions, not on cage microenvironment. Recommended room ventilation rates (10 to 15 outside air changes per hour [ACH]) are based on keeping odors below objectionable levels for humans and have little scientific basis. Recent research shows that the recommended room air exchange rate of 10 to 15 ACH is energy intensive yet does not ensure adequate air quality for laboratory animals. Field studies show that numerous types of air diffusers are being used in typical laboratory animal rooms, and most rooms have high-supply, high-return systems. Expert survey results indicate that designers prefer or specify laminar flow ceiling diffusers, low exhaust location and small laboratory rooms.
KEYWORDS animal house, laboratory, indoor air quality, ventilation system
#NO 9782 Numerical computation of airflow in air conditioning automobile compartment.
AUTHOR Xuejun S, Zhijiu C, Zongcai Q
BIBINF Japan, proceedings of the 5th International Conference on Air Distribution in Rooms, Roomvent '96, held Yokohama, Japan, 17-19 July, 1996, Volume 2, pp 249-254.
ABSTRACT This paper describes two-dimensional numerical simulation of steady air flow in air-conditioning automobile compartment with SIMPLEST method, body-fitted coordinate is used to set up computational grid, while solid-gas coupling heat transfer in the compartment is solved with whole-field-solving method, the effect of natural convection on airflow is taken into account. It is concluded that the location of inlet vent and outlet vent and inlet vent angle have great effect on air flow velocity and temperature distribution in the passenger compartment. The results of this paper lay a foundation for the study of ventilation optimization design in the chamber and comfort control of air-conditioning automobile system.
KEYWORDS numerical modelling, air flow, air conditioning, motor vehicle
#NO 9854 Maximum velocity of return flow close to the floor in a ventilated room - experimental and numerical results.
Karimpanah M T, Sandberg M
UK, Air Infiltration and Ventilation Centre (AIVC), 1996, proceedings of 17th AIVC Conference, "Optimum Ventilation and Air Flow Control in Buildings", Volume 1, held 17-20 September 1996, Gothenburg, Sweden, pp 263-271.
The problem of sensation of draught in ventilated spaces is connected to inappropriate velocities in the occupied zone. In Scandinavia, velocities higher than 0.15 m/s are said to be an indicator of that occupants are likely to feel discomfort. Therefore knowledge of the flow field (both mean velocities and fluctuations) is necessary. Both experimental and numerical analysis of the flow field in a full scale room ventilated by a slot inlet, with two inlet Reynolds numbers 2440 and 7110, have been carried out. Results from both approaches show that the location of the maximum velocity near the floor is nearly independent of the Reynolds number. For a two-dimensional room, the maximum velocity at the floor level occurred at about 2/3 room length from the supply. The distance from the floor level is dependent on the inlet Reynolds number. The velocity profiles far away from the wall opposite to the inlet device have the same character as a wall jet profile. However, close to the corners they are transformed. The relative turbulence intensities measured in the return flow region are questionable, because of a hot wire's inability to record large fluctuations at low mean velocities. These turbulence intensities close to floor level vary from 15 to 80% and as the authors have pointed out previously hot wires do not indicate the real value of the turbulence intensities beyond 20%. Difficulties appear in numerical predictions of return flow properties. Comparison between predicted values and experimentally obtained values show a reasonable agreement. This is promising for future CFD-predictions. However, there is a need for an appropriate measurement technique that can cope with reversing flow.
air flow, draughts, human comfort, measurement technique
#NO 9876 The evolution of ventilation in manufactured housing in the Northwestern United States.
Stevens D, Lubliner M, Davis B
UK, Air Infiltration and Ventilation Centre, (AIVC), 1996, proceedings of 17th AIVC Conference, "Optimum Ventilation and Air Flow Control in Buildings", Volume 2, held 17-20 September 1996, Gothenburg, Sweden, pp 497-509.
Electric utilities in the Pacific Northwest have spent over $100 million to support energy efficiency improvements in the HUD-code manufactured housing industry in the Pacific Northwest over the past several years. Over 65,000 manufactured housing units have been built since 1991 that exceed the new HUD standards for both thermal performance and mechanical ventilation that became effective in October, 1994. All of these units included mechanical ventilation systems that were designed to meet or exceed the requirements of ASHRAE Standard 62-1989. This paper addresses the ventilation solutions that were developed and compares the comfort and energy considerations of the various strategies that have evolved in the Pacific Northwest and nationally. The use and location of a variety of outside air inlets will be addressed, as will the acceptance by the occupants of the ventilation strategy.
mobile home, ventilation system, energy efficiency
#NO 9980 Air flow and thermal comfort simulation studies of wind ventilated classrooms in Malaysia.
Rahman S A, Kannan K S
Pergamon, 1996, "Renewable Energy", proceedings of the World Renewable Energy Congress, held Denver, Colorado, USA, 15-21 June 1996, Volume 1, pp 264-267.
A CFD software called VORTEX is used as a tool to simulate air flow and thermal comfort in naturally wind ventilated classrooms of an educational institution, which are a different locations, have different configurations and slightly differing outdoor environmental conditions. Simulations of the various classrooms are compared to get the most thermally comfortable and uncomfortable naturally ventilated classroom. An analysis of the simulations will be done, taking into consideration, among other, location of inlets and outlets and the sheltering effect of the surrounding built-up environments. Recommendations will then be made on how to improve the ventilation of the least comfortable room, based on hypothetical simulation results.
air flow, thermal comfort, simulation, school
#NO 10068 Numerical study on the air flows system with heat sources in an indoor telecommunication room.
Nho H G, Kim W T
Indoor Air '96, proceedings of the 7th International Conference on Indoor Air Quality and Climate, held July 21-26, 1996, Nagoya, Japan, Volume 2, pp 1021-1026.
Air-flows and temperature distributions in an indoor telecommunication room with switching equipment, have been simulated in two models. Two separate models are applied; CASE 1 is a Upper Air Supply and Lower Return Flow System (LSURFS). and the other of CASE 2; is a lOwer Air Supply and Upper Return Flow System (LSURFS)> In addition to the influence of model type, the effects of the location of inlet/outlet and switching equipments as a heat source at each model are observed.
air flow, modelling
#NO 10171 Managing exposure to indoor air pollutants in residential and office environments.
Tichenor B A, Sparks L E
Indoor Air, No 6, 1996, pp 259-270, 10 figs, 18 tabs, refs.
Sources of indoor air pollutants in residential and office environments can be managed to reduce occupant exposures. Techniques for managing indoor air pollution sources include: source elimination, substitution, modification, pretreatment, and altering the amount, location, or time of use. Intelligent source management requires knowledge of the source's emission characteristics, including chemical composition, emission rates, and decay rates. In addition, knowledge of mechanical and natural outdoor air exchange rates, heating/air-conditioning duct flow rates, and local exhaust fan (e.g., kitchen, bathroom) flow rates is needed to determine pollutant concentrations. Finally, indoor air quality (IAQ) models use this information and occupant activity patterns to determine instantaneous and / or cumulative individual exposure. This paper describes a number of residential and office scenarios for various indoor air pollution sources, several ventilation conditions, and typical occupant activity patterns. IAQ model predictions of occupant exposures for these scenarios are given for selected source management options. A one-month period was used to compare exposures; thus, long-term exposure information is not presented in this paper.
pollutant, indoor air quality
#NO 10183 Thermal comfort and air quality in three mechanically ventilated residential buildings.
Kruger U, Kraenzmer M
Indoor Air, No 6, 1996, pp 181-187, 9 figs, 2 tabs, refs.
Thermal comfort and air quality were studied in three multi-family buildings located in urban environments. Measurements of air velocities close to the supply devices are presented along with measurements of CO, TVOC, NO and NO2. In addition, particle measurements were carried out to check the filter efficiency in one of the buildings (S1) which is specially designed for people with allergy problems. The total air change rate for this building is higher than for normal residential buildings and three different types of air filter are installed in the ventilation system. The results of the thermal comfort measurements in the buildings vary considerably. For two of the buildings thermal comfort can be regarded as acceptable, but can be further improved. The selection and location of the air inlet devices in the third building are not acceptable. The monitoring of the contaminants outdoors and indoors was carried out for diurnal periods. The measured contaminants outside building S1 show good correlation between each other, and the concentrations of gases and particles were considerably lower in the supply of air than in the outdoor air outside the apartment where the measurements were made. The importance of not taking samples over too short a period of time is also shown.
thermal comfort, indoor air quality, mechanical ventilation
#NO 10210 Application of the "age of air" concept in evaluating the ventilation characteristics of a cleanroom.
Liu D L, Lin W H, Li C S, Wang C S, Shih T S
Indoor Air '96, proceedings of the 7th International Conference on Indoor Air Quality and Climate, held July 21-26, 1996, Nagoya, Japan, Volume 4, pp 145-149.
This study has the objective of applying the "age of air" concept and tracer gas techniques in the evaluation of ventilation characteristics of workplaces equipped with a general ventilation system. A Class 10K cleanroom was selected for this study and CO2 was used as a tracer gas. After the tracer gas was released in the form of a pulse into the cleanroom, its concentration was measured as a function of time at various locations by non-dispersive infrared photometers. The average of air at each location was then calculated from the CO2 concentration data. The results show that the average age of air varied markedly from location to location, indicating that the air in the cleanroom was not well mixed. An examination of the flow pattern in the cleanroom reveals that the design of the air inlets and outlets was inappropriate. The study has demonstrated that the use of the "age of air" concept can provide a clear picture of the airflow pattern.
ageing, cleanroom, ventilation system
#NO 10224 Designing HVAC systems for optimum indoor air quality.
Lizardos E J
Energy Engineering, Vol 90, No 4, 1993, pp 7-29, 14 figs.
States that HVAC system design must address both high indoor air quality as well as energy efficiency. Points out that economic considerations such as installation and operating costs have impaired many conventional system designs to the point of compromised indoor air quality. Discusses many HVAC design parameters that are critical to achieving adequate indoor air quality. Topics include location of building fresh air intakes and exhaust air outlets, economiser systems, airflow tracking, filtering systems, sound attenuation, humidification systems, room air distribution, coil drain pans and condensate traps, duct zoning, localised exhausts and temperature and humidity control.
indoor air quality, ventilation system, energy efficiency
#NO 10350 Mechanical ventilation in HUD code manufactured housing in the Pacific Northwest.
Lubliner M, Stevens D, Davis B
USA, Ashrae Transactions, Vol 103, Part 1, 1997, proceedings of the Ashrae Winter Meeting, Philadelphia, 25-29 January 1997.
Electric utilities in the Pacific Northwest have spent more than $100 million to support energy efficiency improvements in the Housing and Urban Development (HUD) code manufactured housing industry in the Pacific Northwest over the past several years. More than 65,000 manufactured housing units have been built since 1991 that exceed the new HUD standards for both thermal performance and mechanical ventilation that became effective in October 1994. All of these usits included mechanical ventilation systems that were designed to meet or exceed the requirements of ASHRAE Standard 62-1989. This paper addresses the ventilation solutions that were developed and compares the comfort and energy considerations of the various strategies that have evolved in the Pacific Northwest and nationally. The use and location of a variety of outside air inlets will be addressed, as will the acceptance by the occupants of the ventilation strategy.
#NO 10564 Controlling ventilation and space depressurization in restaurants in hot and humid climates.
Cummings J B, Withers C R, Shirey D B
UK, Air Infiltration and Ventilation Centre, proceedings of "Ventilation and Cooling", 18th Annual Conference, held Athens, Greece, 23-26 September 1997, Volume 1, pp 153-162.
Testing was performed in 9 restaurants to identify uncontrolled air flows and pressure imbalances, building and duct system airtightness, building air barrier location, pressure differentials, building air flow balance, and ventilation rates. All restaurants and depressurized under normal operating conditions, ranging from minus 1.0 to minus 43 pascals. Space depressurization is a function of exhaust fan flow rates, missing or undersized make-up air, intermittent outdoor air caused by the cycling of air handlers, dirty outdoor air and make-up air filters, and building airtightness. Ventilation rates were found to be high, generally exceeding ASHRAE 62-1989 minimum recommended levels. Pressure imbalances and excessive ventilation rates impact energy use, heating/cooling system sizing, indoor comfort and humidity, building moisture damage, mold growth, combustion equipment problems, and indoor air quality. The objective of good restaurant air flow management (in hot and humid climates) are to: 1) achieve positive pressure in the building under a majority of operating conditions, 2) avoid excessive ventilation, and 3) maintain air flow from dining area to kitchen, all while minimizing heating/cooling energy use and achieving acceptable dehumidification (<60% RH most of the time). Recommendations are presented to achieve these objectives.
hot climate, humidity, restaurant
#NO 10769 On the assessment of ventilation performance with the aid of numerical simulations.
Peng S H, Holmberg S, Davidson L
UK, Building and Environment, Vol 32, No 6, 1997, pp 497-508, 5 figs, 28 refs.
The assessment of ventilation performance is discussed. New local indices are developed with the aid of numerical simulations to quantify air diffusion and contaminate dispersion. The local purging effectiveness, A sp is an index for evaluating the contribution of each inlet in a multi-inlet system. The local specific contaminant-accumulating index x, can be used to indicate the tolerance of a ventilation flow to contaminants. A sp and x can be derived from transport equations. A method based on age-variation analysis is used to define A sp and the Expected Contaminant Dispersion Index (ECDI). The latter is an index for forecasting contaminant dispersion emitted at a specific location with unknown source strength. These new scales and methods can be used to assess ventilation performance.
numerical modelling, ventilation performance, inlets
#NO 11137 Natural ventilation of the contact theatre.
UK, Air Infiltration and Ventilation Centre, supplement to proceedings of "Ventilation and Cooling", 18th Annual Conference, held Athens, Greece, 23-26 September 1997, 6 figs, 4 tabs.
This paper describes the design and development of the natural ventilation system of the new Contact Theatre Complex Manchester, UK, designed by A Goldrick of Short Ford Associates. The ventilation design is based on a stack dominant system using an "H-Pot" chimney configuration. The paper describes the development of the ventilation design of both the studio theatre and main auditorium ventilation systems. These have been developed with the aid of wind tunnel and CFD testing in order to produce a strategy and design relatively insensitive to wind direction, yet providing sufficient ventilation to overcome the high heat gains expected from an audience and stage lighting. The potential for conflicts between wind and buoyancy forces have been reduced through the location and positioning of inlets and through the sizing and design of the stack and H-pot devices.
theatre, natural ventilation
#NO 11324 Air distribution in a furnished room ventilated by mixing ventilation.
Nielsen J R, Nielsen P V, Svidt K
The Canadian Environment Industry Association (CEIA), 1997, proceedings of the 5th International Symposium on Ventilation for Contaminant Control, held in Ottawa, Ontario, Canada, September 14-17, 1997, Volume 2, pp563-574, 8 figs, refs.
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 furniture volume are simulated. The simulations are made in three different lengths of the room. The investigations are concerning influence of the furniture on the wall jet under the ceiling and the maximum velocity in the occupied zone. Two methods to determine the maximum velocity in the occupied zone are developed. The first method uses the total length of the furniture (volume) as a parameter and the second uses the downstream distance from the inlet to the beginning of the furniture (volume) as a parameter. It can, on basis of the investigations made in this paper, be concluded that normal office furniture does not influence the air movements in the upper part of the room but it reduces the maximum velocity in the occupied zone compared to an empty room. This reduction is dependent of the length and location of the furniture.
air distribution, mixing ventilation
#NO 11325 Local supply and exhaust air - effect of different combinations on workers' exposure.
The Canadian Environment Industry Association (CEIA), 1997, proceedings of the 5th International Symposium on Ventilation for Contaminant Control, held in Ottawa, Ontario, Canada, September 14-17, 1997, Volume 2, pp 597-605, 3 figs, 1 tab, refs.
Efficient local ventilation techniques using a low-velocity vertical air supply combined with local exhaust have recently been introduced. In this presentation the effects of these basic local ventilation measures on worker's exposure has systematically been studied. The effects of the exhaust location, the use of a local air supply, and the influence of the worker's posture on the worker's exposure to contaminants was investigated using a full 2 to the power of 4 factorial experimental design. The worker was imitating hand lay-up molding and was working with a soft roller at a table as the tracer gas (SF6) was injected into the roller. The concentration of tracer gas was measured within the worker's breathing zone with an infrared analyzer. The use of exhaust slot between the worktable and the worker was the most effective factor. Also, the use of a local air supply was almost as effective as the exhaust slot. The use of exhaust hoods on the opposite side of the contaminant source including the posture of the worker were of minor effect. The lowest exposure was achieved when the air supply was used in combination with both the exhaust slot and the exhaust hoods.
outdoor air, workplace
#NO 11572 Reentrainment of pollutants from exhausted air - discussion of different types of regulatory requirements.
UK, Air Infiltration and Ventilation Centre, proceedings of "Ventilation Technologies in Urban Areas", 19th Annual Conference, held Oslo, Norway, 28-30 September 1998, pp 380-387.
In many existing ventilation systems unintentional reentrainment of pollutant, due to improper location of exhaust and air intake, decreases quality of indoor environment. Unfortunately, the more precise method of assessment of exhaust plume behaviour, the more difficult potential application in regulatory codes and standards. The aim of the paper is to discuss advantages and disadvantages of different types of the models and their applications in regulatory requirements. Discussion addresses two standards: BSR/ASHRAE Standard 62-1989R Public Review Draft (August 1996) and new Polish building code. The conclusions highlight that at the moment there is no good procedure (simple and precise enough) to be commonly used in standards. The necessity for further research is pointed out.
building regulations, intake positioning
#NO 11576 A simple interactive design tool for sizing, locating and determining pollution attenuation features of urban air inlets suitable for office buildings.
UK, Air Infiltration and Ventilation Centre, proceedings of "Ventilation Technologies in Urban Areas", 19th Annual Conference, held Oslo, Norway, 28-30 September 1998, pp 414-423.
The paper identifies successful ways of applying natural ventilation to non domestic buildings located in urban areas. Whilst noise and contaminant pollution sources are a problem, methods of avoiding these emissions are discussed. A review of literature has established that pollution problems arise for buildings which are in close proximity to roads, railways, airports and local industries. Location of ventilation air inlets will affect the quality of indoor air, therefore it is essential that they are located in ways that minimise the ingress of external pollutants. Potential pollution avoidance strategies include locating vents on sheltered facades and positioning central inlets at a sufficient height from emissions. Wind flow patterns around buildings have an important impact on air quality, and a simple model is discussed that determines the decrease in pollutant concentrations between emission sources and air intakes.
Adequate ventilation is required to limit the number of occasions when indoor temperatures are uncomfortable. A series of well established models are presented based on different natural ventilation concepts. These models can be used to size air inlets for any building, to provide specified ventilation rates on any floor. All issues discussed in the paper form part of an interactive design tool that provides best practice guidelines for minimising the impact of urban pollution, selecting suitable air inlets, and sizing them so as to provide adequate ventilation during the summer.
outdoor air, traffic pollution, inlet positioning, wind effects
#NO 11746 Performance of curtain walls for pre-heating air.
Hauser G, Heibel B
Slovenia, Maribor, University of Maribor, 1998, proceedings of Third SITHOK-3 International Congress, May 9-11, 1998, Maribor, Slovenia, pp 117-126, 8 figs, 9 refs.
For state of the art buildings ventilation heat loss can exceed 50 percent of the total heat loss of the building. Balanced ventilation systems with heat recovery from the exhaust air lead to high costs for ducts. Alternatively, the incoming air of exhaust ventilation systems can be pre-heated by curtain wall facades.
A newly developed simulation program for transient analysis of curtain wall systems is validated by measurements. Parameter studies for pre-heating air with curtain walls are presented. Location, orientation, construction, and geometry are considered. The calculations show that the heat demand for ventilation can be reduced by 50 percent. Efficient systems have a translucent curtain wall and are attached to a thermally insulated wall facing south. Special advice regarding optimal construction is derived from the hydrodynamics of the systems compared. The depth of the air gap can be optimised to values of 2 to 24 mm. The performance of curtain walls for pre-heating incoming air can be estimated over a wide range of parameters.
curtain walling, thermal performance
#NO 11762 Sizing and location of passive ventilation openings.
Irving S J, Concannon P J, Dhargalkar H S
UK, ETSU, S/N8/00142/REP, 1995, 37 pp.
Solar driven natural ventilation is becoming an increasingly important strategy for the design of commercial buildings in the UK. Such buildings are becoming increasingly attractive to the market because they offer a combination of reduced environmental impact whilst offering the user an increased facility for individual control. One of the barriers to the further uptake of naturally ventilated buildings is the problem associated with the sizing of natural ventilation openings. Current design methods rely on rather complex computer based design tools which require skill and experience to use effectively. The purpose of this project was to develop some simpler design guidance and/or procedures which would assist the design team to get the fundamentals of the building design right. This requires a method which can be used at the concept design stage. In order to ensure a wide uptake of the results, the method has been developed in parallel with the drafting of the CIBSE Applications Manual on natural ventilation in non-domestic buildings. The project started out with the intention of developing a series of design charts or nomograms which would cover the range of parameters typical of non-domestic building designs in the UK. Initial analysis soon demonstrated that such an approach would be very time consuming, and the results would probably be rather limiting for use in practice. Consequently the project concentrated on developing a design oriented methodology which placed no restrictions on built form or input parameters. This methodology has become known as the "inverse solver". The inverse solver is a method which turns the current approach to design on its head. Rather than seeking to size ventilation openings by an iterative procedure using simulation tools, it establishes a means of calculating opening sizes directly. This means that the method is very fast and direct, and ideally suited to concept design. The methodology has been developed in two forms: a series of worksheets covering the principal design strategies (buoyancy driven and wind driven), and a computerised implementation of the method in a standard spreadsheet. The method has then been "proven" by designing a series of generic buildings using the inverse solver, and then testing the performance of the design by analysing the building performance using an established multi-zone ventilation program. The results showed maximum deviations of about 1% which establishes a high degree of confidence in the method.
commercial building, inlets
#NO 11881 Measuring adjacent building effects on laboratory exhaust stack design.
Wilson D J, Fabris I, Ackerman M Y
USA, ASHRAE, 1998, in: the ASHRAE Transactions CD, proceedings of the 1998 ASHRAE Annual Meeting, held Toronto, Canada, June 1998, 16 pp, 22 figs, 1 tab, refs.
Current methods for designing exhaust stack height and exit velocity are based on avoiding contamination of the roof, walls, and nearby ground surface of the building on which the stack is located. Usually, no account is taken of the effect of adjacent buildings that add turbulence and increase dispersion if they are located upwind and may be contaminated themselves if they are downwind of the emitting building. To account for these adjacent building effects, ASHRAE Research Project 897 used water-channel simulation of the atmosphere to evaluate rooftop contamination in more than 1,700 different configurations of adjacent building height, width, spacing, stack location, stack diameter, height, and exit velocity. Exhaust stacks on scale models of flat-roof buildings were tested using fluorescent dye tracer illuminated by thin laser light sheets, with digital video images to measure dilution in the exhaust plume at roof level air intake locations. The results show that high stacks and exit velocities that represent good design on an emitting building can be less effective and are sometimes counterproductive in reducing contamination of the roof of a nearby adjacent building. The implications of the study for developing practical stack design guidelines are discussed in this paper.
laboratory, exhaust stack
#NO 11911 Large-scale physical model studies for an atrium smoke exhaust system.
Lougheed G D, Hadjisophocleous G V, et al
USA, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc (ASHRAE), 1999, in: the ASHRAE Transactions CD, proceedings of the 1999 ASHRAE Winter Meeting, held Chicago, USA, January 1999, 23 pp, 23 figs, 1 tab, refs.
This paper presents results of a project initiated by ASHRAE and the National Research Council of Canada. The project applies both physical and numerical modeling to atrium smoke exhaust systems to investigate the effectiveness of such systems and to develop guidelines for their design.
In this paper, results were obtained from a series of tests conducted using a large-scale physical model., The results from the physical model studies are used to investigate the effect of various parameters including fire size, volumetric flow rate for the smoke exhaust system, and the number and location of the exhaust inlets on the conditions in the atrium.
atrium, smoke movement, modelling
#NO 12004 Multipoint monitoring shows ventilation effectiveness.
USA, IEQ Strategies, April 1999, pp 10-14, 5 figs.
Case study of a proactive investigation by college officials to determine what impact the vehicular traffic from several major and often congested commuter highways and a large rail yard had on the indoor air quality in the five contiguous school buildings and whether the school's ventilation system was performing adequately. The investigators came to three major conclusions: due to the location of the college and the local traffic patterns, exposure to vehicle exhaust is unavoidable and often permeates all building areas; CO concentrations are well below federal guidelines, although occupants may notice some unpleasant odours; the building's ventilation system appears to be distributing adequate outdoor air to occupied spaces.
ventilation effectiveness, educational building, pollutant, outdoor air
#NO 12155 Measurements of ventilation performance in a retrofitted conference room.
Roulet C-A, Foradini F, Cretton P, Schorp M
EPIC '98, Volume 2, pp 498-503, 6 figs, 1 tab, refs.
The ventilation system of a 60 seats conference room was retrofitted to improve indoor air quality. The old, mixing type installation was replaced by a displacement ventilation system. However, the building layout did not allow an optimum location of air inlets and outlets. It was therefore interesting to measure the actual performance of the new system.
Using tracer gas techniques, the age of air was mapped within the room, and the ventilation effectiveness was measured in various configurations. The actual air flow rates were also measured in the ventilation system. Configurations were: empty room, room occupied by immobile, heated artificial bodies, and room with real occupancy.
The air change efficiency was found unsatisfactory, and recommendations were given to improve it. The ventilation system was modified, the room was made more airtight, and measurements were performed again, which proved the efficiency of these modifications.
The contribution presents the experimental planning, the results, and the practical conclusions, which can be deduced from this experiment.
auditorium, retrofitting, ventilation performance, tracer gas, measurement technique
#NO 12613 Analysis of air supply type and exhaust location in laboratory animal research facilities using CFD.
Manning A, Memarzadeh F, Riskowski G L
USA, ASHRAE Transactions, Winter Meeting 2000, Dallas, 7 pp, 12 figs, 1 tab, refs.
The results from a computational fluid dynamics (CFD) study on the effect of air supply diffuser type and exhaust location in a typical animal research laboratory are presented. The results show that low level exhausts produce higher temperatures in the room and cages, but the best in cage ventilation (lowest CO 2 concentrations) compared with ceiling or high level exhausts. Further, the study shows that the slot diffuser seems least sensitive to exhaust position. Finally, the results show that the room concentrations of CO 2 and NH 3 do not show any supply type or exhaust location to be significantly better or worse than any other type. and room.
computational fluid dynamics, thermal comfort, exhaust positioning
#NO 12724 Ventilation strategies for good indoor air quality and energy efficiency.
in: USA, ASHRAE, 1999, "IAQ and Energy 98: Using ASHRAE Standards 62 and 90.1", pp 257-276, 9 figs, 5 tabs, refs.
This paper shows that the cost of space conditioning of buildings is in the same order of magnitude as at cost caused by deteriorated indoor air quality. The requirements for good indoor air quality and energy efficiency have often been considered to conflict with each other; however, buildings with low energy consumption in Europe seem to have also a lower rate of building-related symptoms. This indicates the importance of power design and installation and qualified well-trained operational personnel who understand both the requirements for good indoor air quality and energy efficiency. Several strategies for ventilation are described in this paper by which, at the same level of energy consumption, the indoor air quality is improved or, at the same level of indoor air quality, the energy consumption is reduced. These include the following; proper target and design values of indoor air quality and climate, proper location of fresh air intakes, cleaning of intake air, efficient air distribution in rooms with improved ventilation efficiency, heat recovery from exhaust air, control of ventilation rates by air quality, proper selection and control of airflows, correct balancing of airflows, source control and efficient removal of contaminants, controlling indoor climate locally, and natural ventilation and free cooling
sick building syndrome, ventilation strategy
#NO 12752 Ventilation design in animal research facilities using static microisolators.
USA, ASHRAE Transactions, Winter Meeting 2000, Dallas, 8 pp, 11 figs, 1 tab, refs.
This paper presents the key conclusions from an extensive research project on ventilation design in animal research facilities using static microisolators. This study, which is presented in full in Memarzadeh (1998), considered both experimental and numerical aspects using the computational fluid dynamics (CFD) technique. As well as a summary of various gaseous generation rates for mice, this paper contains conclusions on the effects of changing various parameters within an animal research room on conditions in the cages and in the main room volume itself. These parameters include, but are not limited to, supply type, exhaust location and number, room ventilation rate, and supply air temperature and moisture content.
animal house, instrumentation
#NO 12781 Numerical simulation of two-dimensional room air flow with and without buoyancy.
Sinha S L, Arora R C, Roy S
Energy and Buildings, No 32, 2000, pp 121-129, 10 figs, 20 refs.
This investigation deals with the velocity and temperature distribution in a room heated by a warm air stream introduced at various levels. Numerical solutions of Navier Stokes equations and energy equation have been obtained by SIMPLE and Semi Implicit Method for Pressure Linked Equation-Consistent (SIMPLEC) algorithms. Steady, laminar, and incompressible flow under Boussinesq's approximation has been considered. Solutions are presented for various locations of inlets and outlets, and for different values of Grashof number and Reynolds number. If the outlet is located at a lower level than the inlet, an increase in Gr makes the warm jet almost horizontal, which finally bends downwards towards the exit. An increase in Gr increases the intensity of recirculation and yields uniform temperature distribution. Location of outlet at higher level than the inlet leads to better temperature distribution.
numerical modelling, air flow, jets, air distribution
#NO 12789 Ventilation in 2 or 3 unit multifamily buildings before and after weatherization.
Canada Mortgage and Housing Corporation, December 1999, 29 pp + app,., 11 refs.
This study investigates the fresh air distribution in 2 or 3-unit multifamily buildings before and after weatherization and evaluates the effectiveness of exhaust-only ventilation in providing the minimum recommended fresh air flows to dwelling s in such buildings. Low-rise multifamily buildings often have no mechanical ventilation system and rely on the air leakage through the exterior envelope to provide outdoor air to occupants. Weatherization of the roof space, a common energy conservation measure applied to 2 or 3-unit multifamily buildings (also known as Duplex or Triplex) in Quebec can greatly reduce the equivalent leakage area of the exterior shell and change the location of the neutral pressure plane. Consequently, this has major impact on the outdoor air supply to the building and how it is distributed on a unit-per-unit basis. Field test data characterizing the shell leakage and inter-zonal leakage of a case study building was used to define various pre-and post-weatherization airflow models. Airflow models were introduced in CONTAM a software developed by the National Institute of Standards and Technology (NIST). To determine the air change profiles (fresh air change & total air change) for the individual dwellings. The results of simulations presented herein shed light on the most popular mechanical ventilation strategy used in weatherized low-rise multifamily buildings.
retrofitting, apartment building, air distribution
#NO 12828 Koneellisen poistoilmanvaihdon parantaminen. Radon, vuotiolma ja korvausilma. Improvement of mechanical exhaust ventilation in apartment buildings. Radon leakage flows and intake air.
Kurnitski J, Jokiranta K, Matilainen M
Finland, Helsinki University of Technology, Laboratory of Heating, Ventilating and Air Conditioning, Report B65, Espoo 1999, 77 pp, in Finnish.
The objective of this research was to find improvements for the mechanical exhaust ventilation, which will enable the reduction of draughts, limit leakage flows and reduce radon concentrations, improve the duration of intake air flows and the control of air change. In the research, a new intake air device that turns intake airflow uniformly back to the radiator was tested in two apartments, where conditions were monitored before and after installing air intakes. In addition, instant measurements were carried out in seven detached houses and in seven apartments. The behaviour of mechanical exhaust ventilation and the need for control was assessed by computer simulation, where the effects of the number of air intakes, location and tightness of the building, etc, on the pressure conditions and air flow were studied. A general conclusion from the simulations was that mechanical ventilation will not function in the case of windy building sites. At an open building site, the reverse flows in air intakes could not be avoided and, in opposite facades, large asymmetry in intake air flows was formed. Leakage flow through the base floor to apartments cannot be avoided according to the results of simulation and measurements. Air tightness of the base floor is lower compared to the other parts of the building envelope due to ducts and pipes leading through and a notable amount of intake air can be leaked through the base floor. The common air intakes can transport into the room, without notable draught, 10 l/s airflow that consists of 6 l/s airflow through the vent and 4 l/s leakage of the façade. This airflow corresponds to an air change rate of 0.5 ach that can be recommended for air change during day and night without timer-control since the ventilation load is most critical during night. Even in small apartments 0.5 ach air change can be dimensioned by reduced extract flow in the kitchen by a controlled range hood and, if necessary, by reduced extract flow in the bathroom.
mechanical exhaust ventilation, draughts, radon, air leakage, apartment building
#NO 12848 In mine comparison of diesel particulate sampling methods.
Haney R A, Fields K G
Appl. Occup. Environ. Hyg. , Vol 11, No 7, July 1996, pp 717-720, 3 figs, 1 tab, 10 refs.
In an effort to quantify particulate exposures in the mining industry, various organizations have developed diesel particulate sampling instruments. These instruments work on a variety of different principles. These principles include the use of size-selective sampling utilizing inertial impaction, the measurement of respirable combustible dust (RCD), and the measurement of elemental carbon. The RCD methods provide measurements of whole diesel particulate. The size-selective and elemental provide a measurement of a fraction of the diesel particulate matter. The size-selective and RCD methods are limited by filter loading. A series of tests were con ducted to compare the measurements obtained with the various diesel particulate sampling instruments and analytical methods. The tests were con ducted at two underground mining facilities, a zinc mine and a potash mine. Similar tests are scheduled to be conducted in coal and other dieselized metal mines. A portable test chamber containing 30 sample ports was utilized for these tests. The sample chamber inlet was equipped with two cyclones that matched the American Conference of Government Industrial Hygienists respirable dust criteria at air flows up to 30 L/min. The three different sampling devices were attached to the chamber in groups of ten for each test. The sample pumps utilized with the elemental carbon filters was varied from 1.0 to 1.7 L/m depending on the test location to reduce the overloading of the filter. This article provides a description of the test procedures and preliminary summary of the results. For each type of measurement, the average for each sample is compared and a coefficient of variation is calculated.
particulate, mining, sampling, vehicle exhaust
#NO 12850 Railroad diesel exhaust: concentration and mutagenicity.
Hammond S K, Smith T J, Woskie S R, et al
Appl. Occup. Environ. Hyg., Vol 8, No 11, November 1993, pp 955-963, 4 figs, 3 tabs, 24 refs.
High volume fixed location samples of particles and vapor phase components were collected on filters and XAD-2 resin, respectively, to study the concentrations and mutagenicity of diesel exhaust in locomotive repair shops at four railroads. The geometric mean concentration were 96 ug/m3 [geometric standard deviation (GSD) = 2.14] for 23 samples of respirable particles, 164 ug/m3 (GSD = 1.86) for 26 samples of total particles. and 432ug/m3 for 9 samples of vapor phase components. Approximately 30 to 40 percent of the particle mass was extractable in dichloromethane. Chemical class separation of these extracts by normal phase liquid chromatography yield nearly half the mass in the aliphatic fraction, less than one third in the aromatic fraction, and about one quarter in the polar fraction. Extracts of particle samples wee found to be mutagenic in the Salmonella typhimurium forward mutation assay system. Most of this activity either with or without metabolic activation. The locomotive repair shop air was approximately 1 order of magnitude more mutagenic than urban air. These elevated levels of mutagens found in diesel locomotive repair shops are consistent with the increased mortality from lung cancer tat has been found among railroad workers.
railway, vehicle exhaust, cancer
#NO 13033 Ventilation for buildings - ductwork - requirements for ductwork components to facilitate maintenance of ductwork systems.
UK, British Standards Institute (BSI), DD ENV 12097:1997, Draft for Development, 24 pp.
This European Prestandard has been prepared by Technical Committee CEN/TC 156 "Ventilation for buidlings". It is part of a series of standards for ductwork used for ventilation and air conditioning of buildings for human occupancy. It applies to ductwork in buildings subject to human occupancy. It specifies requirements for dimensions, shape and location for openings, access and inspection covers and access doors for cleaning and service in supply and exhaust air ducts which conform to prEN 1505, prEN 1506 and prEN XXXD.
ductwork, maintenance, ventilation system
#NO 13049 Selective ventilation in large enclosures.
Calay R K, Borresen B A, Holdo A E
Energy and Buildings, NO 32, 2000, pp 281-289, 7 figs, 18 refs.
A new method for providing ventilaton in large enclosures, which utilises the principle of 'selective withdrawal' of contaminants while ensuring energy efficiency and allowing a better use of space, is presented in this study. The concept is based on dividing the enclosed space ventilation-wise into separate zones using a combination of horizontal partitions by stratification and vertical partitions by temporary walls. This gives a high degree of flexibility in the use of available space. The relative influence of all the parameters on the flow patterns inside an enclosure is discussed in order to identify the design parameters that should be controlled to apply the technique successfully. An experimental study in a scale model was conducted, which provided a better understanding of the physical processes that occur in such enclosures. The influence of exhaust location on the flow field was studied in particular. It was found that by controlling the position of exhaust the stratification effects are enhanced and maintained at a desired level in order to achieve a successful utilisation of the selective ventilaton system.
displacement ventilation, large building, air flow pattern, stratification
#NO 13210 Location of air inlets to avoid contamination of indoor air: a wind tunnel investigation.
Green N E, Etheridge D W, Riffat S B
Building and Environment, No 36, 2001, pp 1-14, 9 figs, 6 tabs, 23 refs.
The location of air intakes is of prime importance in buildings that are situated in close proximity to busy urban roads. If intakes are placed where the concentration of traffic pollution is high then indoor air concentrations can reach similarly high levels. This paper presents the findings from a wind tunnel investigation into the dispersion of a simulated traffic pollutant in a 1:100 scale model. The concentrations at different points on a building in the model are measured and a comparison with full scale data is made.
air intakes, wind tunnel, indoor air quality
#NO 13310 The effect of object positions on ventilation performance.
Cho Y J, Awbi H B
UK, Oxford, Elsevier, 2000, proceedings of Roomvent 2000, "Air Distribution in Rooms: Ventilation for Health and Sustainable Environment", held 9-12 July 2000, Reading, UK, Volume 1, pp 433-438, 5 figs, 1 tab, refs.
The effect of the change in object positions (i.e. office furniture) on the air quality in a room was studied using zonal purging floe rates. In relation to the zonal purging floe rate in a room, the transfer probability from the inlet to a certain zone can provide information on the amount of fresh air from the inlet to the zone. In this case study, the probability obtained from Markov chain theory was used to analyze the ventilation performance. Also the mean ventilation effectiveness obtained from the transfer probability was compared with the traditional mean ventilation effectiveness for the room. The velocity fields in a two dimensional parametric room (6m x 2.7m) were derived from CFD simulation under isothermal conditions, The velocity fields were used to calculate the interconnecting flow rate between zones, and to obtain the velocity data for the whole room and the occupied zone. Several different arrangements of objects (representing room furniture) were used to find the optimum location of the objects. It was found that the mean ventilation effectiveness using the zonal purging flow rate concept is in agreement with the traditional mean ventilation effectiveness. Findings from this paper show that the object positions can play a key role in influencing ventilation performance, either in a positive or in a negative way. Depending on the location of object and airflow pattern, the presence of an improvement in the air distribution. Also, an increase in the object lengths and a decrease in the free volume of the room do not always mean that the ventilation effectiveness decreases. The zone where the maximum velocity in the occupied zone occurs was the optimum location of an object in the room investigated.
Object positions, Mean ventilation effectiveness, mixing ventilation, CFD, zonal purging flow rate, transfer probability from inlet, Free volume.
#NO 13346 Study of the ventilation efficiency under some typical air flow conditions in a mechanically ventilated room.
Castanet S, Beghein C, Inard C
UK, Oxford, Elsevier, 2000, proceedings of Roomvent 2000, "Air Distribution in Rooms: Ventilation for Health and Sustainable Environment", held 9-12 July 2000, Reading, UK, Volume 2, pp 837-842, 4 figs, 2 tab, refs.
The present study deals with indoor air quality and is mainly based on an experimental work. The experimental set up is a full scale test cell with a ventilation system which comprises a fixed air supply and a mobile extract. A source of pollutant continuously supplies tracer gas at the centre of the cell. We carried out 12 tests under steady state and with various conditions. The test parameters were the exhaust location, the fresh air flow rate and the supply air temperature. The analysis of the air temperature, air velocity and tracer gas concentration isovalues clearly show the effect of each parameter on the ventilation efficiency.
Ventilation efficiency, temperature efficiency, full-scale experiment, tracer gas, Archimedes number, Reynolds number, thermal length
#NO 13358 A numerical study on pollutant removal effectiveness of a room.
Collignan B, Riberon J
UK, Oxford, Elsevier, 2000, proceedings of Roomvent 2000, "Air Distribution in Rooms: Ventilation for Health and Sustainable Environment", held 9-12 July 2000, Reading, UK, Volume 2, pp 931-936, 7 figs, refs.
Ventilation system has to be designed in order to strike a balance between indoor air quality and energy requirements. So, the ventilation efficiency can be considered as a major issue to deal with this objective. In order to assess the efficiency of pollutant from a room, a methodological approach using CFD has been developed. It is based both on local and global indexes. These indexes take into account the distribution of pollutant concentration inside room and the mean concentration at the exhaust with respect to the occupant location. Based on an isothermal tow dimensional test case of IEA Annex 20, a sensitivity analysis has been carried out to calculate the pollutant concentration with regards to the exhaust vent and pollutant source locations. The results obtained with the above-mentioned indexes have shown that each configuration can be characterised in connection with the efficiency of pollutant elimination. In addition, these indexes show how the connected location of both exhaust vent and pollutant source affects the indoor air quality.
Ventilation efficiency, numerical simulation, contaminant removal effectiveness
#NO 13411 Guidelines for minimising the ingress of urban pollution
in: "Indoor Environment and Air Quality", UK, Mid Career College, 1999, pp 51-61, 2 figs, 1 tab, 11 refs.
Aims to break down barriers to concepts of natural ventilation. Part of the NatVent study, which explores successful ways of avoiding the barrier which urban pollution places before natural ventilation. Simple steps that can be taken include the intelligent location of air intakes to office blocks. Both contaminant pollutants and noise exposure are significantly reduced by placing intakes on sheltered facades such as courtyards and enclosures. Also describes the importance of sizing inlets properly.
outdoor air pollution, natural ventilation