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LL 07: Air Flow Through Building Entrances

AIVC, 2001
AIVC | LL
Bibliographic info: LL 07
Languages: English

Air Flow Through Building Entrances


#NO 11108 A field study of whole house air infiltration in residences.

Yuill G K, Yuill D P

USA, Energy Efficient Building Association Inc., 1997, proceedings of "Excellence in buildings", a conference held in Denver, Colorado, November 5-8, 1997, pp E7-1 to E7-6.

A four part study was carried out on the airtightness of houses. Two identical single story 1360 square foot wood frame houses were used in the study. The tests conducted in the four part study include: comparison of the effects of wet blown cellulose and kraft faced fiber glass wall insulation on the airtightness of a house; comparison of the effects of blown fiber glass and kraft faced fiber glass wall insulation on the airtightness of a house; effects of various wall systems, air tightening materials and techniques on the airtightness of a house, and effects of sealing house components on the airtightness of a house. From the study, the following results were concluded: the majority of air infiltration occurred in the ceiling (40%) and floor (36%) of the houses, and was significantly reduced by caulking and sealing. The walls and doors/windows accounted for 14 percent and 10 percent, respectively, of the houses' air infiltration; a comprehensive whole house caulk and seal job reduced air leakage within the houses by approximately 44 percent; various wall system air tightening techniques, such as installing a housewrap, taping insulating sheathing joints or caulking and sealing, had a notable impact (nine percent) in reducing air infiltration in the houses; wall cavity insulation had virtually no effect on the air tightening of the houses. The complete removal of the wall cavity insulation resulted in only a 1.5 percent increase in air leakage throughout the entire house; the greatest barrier to air flow through a wall was the drywall, followed by several different airtightness treatments.

air infiltration, residential building, air tightness

#NO 11309 A field study of cold air flows through doorways of industrial buildings.

Hejazi-Hashemi M G, Siren K E

The Canadian Environment Industry Association (CEIA), 1997, "Ventilation '97: Global Developments in Industrial Ventilation", proceedings of the 5th International Symposium on Ventilation for Contaminant Control, held in Ottawa, Ontario, Canada, September 14-17, 1997, Volume I, pp 299-306, 6 figs, 1 ref.

A problem, which appears in many industrial buildings is spreading of the outdoor cold air coming in through the doorways and other large openings, causing draught and pollution at the work places, disturbing the proper functioning of the ventilation as well as disturbing some production processes and increasing the maintenance and energy costs. The goal of this study was to achieve quantitative, measured information of the effects of cold air flows in the industrial environment. The method used was field measurements, which were carried out during the wintertime 1996 in industrial buildings located in the northern part of Finland. Totally 12 industrial buildings, representing a wide variety of different situations were monitored. The results show remarkably high cold air flow rates through doorways. Air flow velocities up to 7 m/s and air flow rates up to 60 m3/s were measured. High flow rates occurred especially in tall buildings, where the stack effect is high. As a consequence adverse effects on thermal conditions, ventilation, processes and the energy consumption were observed. The results serve as a base for an analysis, where simple tools are developed for the planning stage of industrial ventilation and especially for the prevention of cold air flows in arctic and sub arctic climates.

industrial building, door, air flow

#NO 11322 Ventilation survey of tuberculosis isolation rooms in five hospitals.

Conroy L M, Franke J E, Dimos J, et al

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 497-508, 2 figs, 3 tabs, 10 refs.

Describes a ventilation study of TB isolation rooms which was conducted in five hospitals during 1993-1995. Mechanical supply and exhaust air flow rates were measured using an Alnor Balometer swinging vane anemometer. Door gap velocity was measured using a TSI Velocicalc hot film anemometer. Air flow direction was determined using MSA acetic acid smoke tubes. Pressure difference was measured using Setra pressure transducers connected to Rustrak Ranger data loggers. The results of each survey were compared with CDC recommendations. Concludes that negative pressure isolation driven by excess exhaust air in the patient room is the most effective strategy for protecting workers and other patients. However pressurised and depressurised anteroom strategies can provide reasonable isolation as well as air flow protection for certain patients who need it. The limitations of the two strategies must be understood by the hospital workers for their protection. Better preventive maintenance programs were needed at the hospitals.

disease, hospital, ventilation strategy

#NO 11528 Effects of a Ventilation Duct on the Performance of a Fume Cupboard

Trevelyan P M J, Elliott L, Ingham D B

Sweden, Stockholm, KTH Building Services Engineering, 1998, proceedings of Roomvent 98: 6th International Conference on Air Distribution in Rooms, held June 14-17 1998 in Stockholm, Sweden, edited by Elisabeth Mundt and Tor-Goran Malmstrom, Volume 1, pp 385-392.

When a fume cupboard is placed in a room with a ventilation duct, the air movement inside and around the fume cupboard is fully three-dimensional turbulent flow. However, in order to understand the fluid flow away from the fume cupboard a much simpler model can be used. This leads to a steady 2D model, with the computational domain including only the sash of the fume cupboard, the room and the entrance into the ventilation duct. In this paper we have used both the k-epsilon turbulence model and the wall function technique to calculate the steady 2D turbulent fluid flow. In addition, a mathematical technique has been employed to map the simpler model onto the upper half of the complex plane, so that the complex potential can be found using a source and a sink on the real axis to represent the ventilation inlet and the exhaust outlet of the room, respectively. The objective of this paper is to reduce the cpu time by restricting the computational domain to a region which only includes the fume cupboard and a small region outside. We establish from a modified version of the potential flow a solution which we can use near the fume cupboard as a specified velocity boundary condition whilst solving the turbulent fluid flow model within the fume cupboard.

duct, fume cupboard, air movement

#NO 11543 Effects of air-curtain to the heat and mass transfer in a typical urban transport vehicle. 

Poh H J, Tso C P, Yu S C M

UK, Air Infiltration and Ventilation Centre, proceedings of "Ventilation Technologies in Urban Areas", 19th Annual Conference, held Oslo, Norway, 28-30 September 1998, pp 101-109.

A computational study had been carried out on hot and cold air interaction across the door of an urban transport vehicle. The studies show that within 20 s after the door is opened all cool air beside the door of the vehicle would flow out when the ambience is 30oC. The mixing flow across the door would cause maximum mass exchange of 0.55 kg/s during the transient phase. An additional cooling load of 0.4 kW is required to cool down the hot air after the door is closed. The constant flow rate and temperature air curtain is effective in preventing hot air from going into the bus. Various factors that affect air curtain effectiveness such as air curtain velocity, delay door opening time and the fan characteristic curve for the air curtain are investigated. It is found that for an ambient 30oC, air curtain of 6 ms -1 with door delaying time 5 s would give the best sealing effect in order to maintain the controlled environment within 24oC.

motor vehicle, cooling

#NO 11549 Controlled natural ventilation for commercial and industrial buildings. 

Knoll B, Phaff J C

UK, Air Infiltration and Ventilation Centre, proceedings of "Ventilation Technologies in Urban Areas", 19th Annual Conference, held Oslo, Norway, 28-30 September 1998, pp 154-167.

The Dutch organization for applied scientific research TNO in Delft developed a system of Controlled Natural Ventilation (CNV). It is produced by the Dutch ventilation firm Braked in Uden. The system controls ventilation grills and windows. Its purpose is: to compensate for fluctuating buoyancy forces (wind and temperature) so that natural ventilation flows are kept on set point value, independent of weather changes and changes in internal heat production; to optimize the air flow distribution over the building to get the highest possible ventilation efficiency; to restrict ventilation openings when draught risks occur. The CNV system is based on a computer program that simulates ventilation. A special inverse version is derived that calculates the optimal ventilation openings for a specific building on each weather condition and for each ventilation set point. The program needs input on local wind effects on the building. They are predicted with another new developed simulation tool, called the 'Cp-Generator'. This special computer program for prediction of wind pressure coefficients (Cp's) is built in as a module in the main program.

Extra features of the CNV system are: rain protection without decrease in flow rate; improved noise reduction; collaboration with mechanical ventilation; anticipation on opening doors; building leakage compensation; adjustment of both flow rate and direction to varying pollution or heat sources; smoother temperature control; special control for smoke ventilation.

building controls

#NO 11639 Kylmien ilmavirtausten torjunta teollisuushalleissa. Suunnitteluohje.

Valkeapaa A, Hejazi-Hashemi S, Siren K

Finland, Helsinki University of Technology, Faculty of Mechanical Engineering, Laboratory of Heating, Ventilating and Air Conditioning, 1998, report B55, 94 pp + app., in Finnish

Cold outdoor air inside industrial buildings causes draught problems and increases energy consumption of the building. Also cold outdoor air has a harmful effect on the processes and ventilation system and the floor area near the door opening cannot be used in productive activity. Furthermore, cold outdoor air is warmed slowly and causes a long duration temperature stratification, which removing is very difficult.

Prevention for cold air flows depends on many contemporaneous factors, such as the climate conditions, the building layout and height, the near terrain, the places of door openings, the number of door openings and the building structures. The most important thing in prevention of cold air flows is to recognise these factors and to understand the interaction between the climate conditions, the near terrain and the building itself. If the building structure disadvantages are not solved by heating and ventilation means, HVAC-engineers have to interface in these structure disadvantages.

The aim of this new planning rule for the prevention of cold air flow is to instruct HVAC-engineers to find the decisions for the prevention cold air flows in the large openings and on the cover of industrial buildings. The planning rule can be used also in the negotiations with customers. Because of that the planning rule includes many photos and pictures of preventing solutions.

The planning rule is developed together with the experts of industrial ventilation and the manufacturers. The planning rule includes the form of risk index, three main decision trees and some auxiliary decision trees. Preventing solutions are introduced among other things the air curtains, the shelter structures of loading docks and the service entrances. The planning rule is complete with the simulation programme CAFCAM, which can calculate air flows through the door openings, the pressure distribution of industrial building and the position of neutral pressure level.

industrial building, building design

#NO 11676 Unplanned airflows can cause perplexing problems in buildings.

Anon

USA, IEQ Strategies, November 1998, pp 12-14.

Unplanned airflow in buildings can provide pollutant pathways and degrade IAQ, sometimes despite the best efforts of those managing the building. The results of unplanned airflow can occur under various conditions: continually, periodically, or when dynamic systems change from stable to unstable operations. Factors such as leaks in the building envelope, pipe chases, electrical conduits, open doors, and leaky windows, can all result in air moving in unintended ways, thus carrying pollutants into occupied spaces. Any of four conditions can result in this unintended airflow: an opening in a building component where there should be a barrier; a barrier in a building component where there should be an opening; the building zone being positive or negative when it should be the opposite; an unanticipated force producing pressure differences in the building. Goes on to describe four case studies.

air flow, building envelope

#NO 11848 Air flow through louvred windows in small rooms.

Oliveira F, Bittencourt L

UK, James & James Ltd, 1988, proceedings of "Environmentally friendly cities", PLEA 98 (Passive and Low Energy Architecture) conference, held Lisbon, Portugal, June 1998, pp 393-396, 9 figs, 14 refs.

In equatorial warm humid climates, ventilation has been largely adopted as a major strategy for natural passive cooling. In those climates the use of porous elements is common to allow for permanent ventilation as temperature rarely drops below 20 Deg.C. Nevertheless, the performance of many building components has not been thoroughly determined, making it difficult to predict buildings performance as ventilation rates, estimated in most simulation codes are often based on apertures typologies from temperate and cold regions. This paper is the result of an experimental assessment carried out at the Universidade Federal de Alagoas, comparing the airflow velocity inside two identical rooms. The rooms were shaped and sized similar to a typical local bedroom (2.80 x 3.50 m) , having the same window area as inlet and a door as outlet, both placed in the centre of external walls of the test rooms. In one of the rooms the aperture would have a permanently open window, while in the other one there was a window with horizontal slates. Air speed near the windows were measured to obtained the resistance to the airflow produced by horizontal slates (with and without mosquito screens), under different wind speed and directions. Results show that the resistance to the airflow may vary significantly as a function of wind speed and direction. 

air flow, window, warm climate, humid climate, passive cooling

#NO 11889 Performance check between whole building thermal performance criteria and exterior wall measured clear wall R-value, thermal bridging, thermal mass, and airtightness.

Kosny J, Christian J E, Desjarlais A O, et al

USA, ASHRAE, 1998, in: the ASHRAE Transactions CD, proceedings of the 1998 ASHRAE Annual Meeting, held Toronto, Canada, June 1998, 11 pp, 10 figs, 13 tabs, refs.

The dynamic thermal performance of an insulated concrete form (ICF) system was analyzed based on a dynamic guarded hot box test at a national laboratory. The same wall configuration was modeled for dynamically changing boundary conditions using the finite difference computer code HEATING 7.2. Thermal mass validation of the model was made by comparing model heat flow predictions to the hot box measured heat flow through an 8 ft by 8 ft ICF clear test wall exposed to dynamic boundary conditions. Good agreement was found between test and computer modeling results.

A series of response factors, heat capacity, and R-values were computed using finite difference computer modeling. They enabled a calculation of the wall structure factors and estimation of the simplified one-dimensional "thermally equivalent wall" configuration. A thermally equivalent wall has a simple multilayer structure and the same thermal properties as a nominal wall. Its dynamic thermal behaviour is identical to the ICF test wall. The thermal and physical properties describing the equivalent wall can be used in whole building one-dimensional energy simulation programs with hourly time steps. The usage of the equivalent wall theory provides a direct linkage from dynamic hot box test to accurate modeling of buildings with walls that contain considerable three-dimensional heat flow within the structure.

The equivalent wall generated for the ICF system was used in a whole building computer model to simulate a single-family residence in six representative U.S. climates. The space heating and cooling loads from the residence with massive ICF were compared to an identical building simulated with lightweight wood-frame exterior walls. Nine light wood-frame walls with R-values from 2.3 - 29.0 were simulated. The heating and cooling loads generated from these building simulations were used to estimate the R-value that would be needed in conventional wood-frame construction to produce the same loads as the ICF system. The resulting R-value is considered an effective R-value for the ICFs, which not only accounts for the steady-state R-value but also the inherent thermal mass benefit. "Effective R-values" for the ICF were obtained by comparison of the thermal performance of the ICF and lightweight wood-frame walls, and they should be understood only as an answer to the question, "What R-value would an identical house with wood-frame walls need to obtain the same space heating and cooling loads as a specific ICF?"

A second major benefit of this ICF system is the airtightness. This paper also analyzes the impact of a 20% reduction in uncontrolled infiltration for the ICF house compared to the wood-frame structure. The 20% reduction is suppoerted by blower door tests on seven ICF houses with a measured 0.0004 leakage area divided by floor area.

thermal performance, air tightness

#NO 11894 Infiltration load in cold rooms.

Elsayed M M

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, 24 pp, 17 figs, 3 tabs, refs.

A two dimensional model was developed to predict the infiltration load to a cold room through its doorway. The governing equations were derived and transformed into dimensionless form. The model showed that the infiltration load to a cold room depends on three dimensionless parameters: the Grashof number of the cold room, the aspect ratio of the room (height to width), and the opening ratio (height of doorway to height of the room). A finite difference technique with a control volume approach was used to solve the governing equations. Staggered grids were used, extending them beyond the doorway to account for the air motion outside the cold room. A SIMPLER algorithm, with finite difference formulation was used to solve the governing equations together with their boundary conditions. The model was used to predict the flow pattern and the temperature distribution in the cold room due to the infiltration through the doorway. The results were also utilized to study the variation of the rate of infiltration and the doorway flow factor with the time measured from the moment the door was opened. The results are presented for the Grashof number from 10 to power of 5 to 10 to power of 7 and 10 to power of 10, and opening ratios of 0.5 to 0.25. Comparisons of results with those in the literature are presented. The good agreement of the simulation with the experiments suggests that the present model is valid for the type of flows compared. 

air infiltration, modelling

#NO 11910 Smoke movement and detector activation in high bay spaces.

Davis W D

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, 13 pp, 9 figs, 7 tabs, refs.

A series of fire experiments were conducted in two aircraft hangars with ceiling heights of 15 m (50 ft) and 22 m (73 ft). The purpose of the experiments was to analyze the activation characteristics of smoke and heat detectors in response to JP-5 and JP-8 pool fires. The 15 m (50 ft) hangar was located in Hawaii, where ambient temperatures were approximately 30 Deg.C (86 Deg.F). The 15 m (50 ft) experiments used fire sizes that ranged from 100 kW (95 btu/s) to 7.7 MW (7300 Btu/s). Experiments were conducted with and without draft curtains in the 15 m (50 ft) hangar. The 22 m (73 ft) hangar was located in Iceland, where ambient temperatures were approximately 12 Deg.C (54 Deg.F). The 22 m (73 ft) experiments used fire sizes that ranged from 100 kW (95 Btu/s) to 33 MW (31000 Btu/s). Draft curtains were present for all the 22 m (73 ft) experiments. Open- and closed-door fire experiments were conducted in both hangars.

Commercial detectors used in the series of experiments included spot smoke and heat detectors, bulb and fusible link elements, projected beam smoke detectors, UV/IR optical flame detectors, and a line-type heat detector. Other instrumentation included thermocouples, mass flow meters, and radiometers.

The analysis of these experiments has led to the following observations:

1. Draft curtains improved the response time of heat detectors and sprinklers at these ceiling heights and reduced the size of the threshold fire needed for activation. Both the plume centerline temperature and the ceiling jet temperature increased in response to the growing smoke layer.

2. Standard response sprinklers were either activated substantially slower or not at all when compared to the activation of quick-response sprinklers at these heights.

3. Trouble windows used for beam-type smoke detectors gave false trouble signals in the presence of dense smoke from JP-5 fires.

4. Tests conducted in the presence of wind and open hangar doors showed that ceiling jet temperatures were substantially reduced but that downwind smoke detectors continued to activate for small fire sizes. Wind speeds inside the hangar ranged from 2 km/h to 32 km/h (1mph to 20 mph).

Based on the observed detector activation, spacing for both spot smoke and heat detectors at these heights was analyzed.

smoke movement, large building, aircraft hangar

#NO 12081 The effect of the distribution of air by blockage of room space - an experimental study.

Sandberg M, Claesson L

Sweden, Stockholm, KTH Building Services Engineering, 1998, proceedings of Roomvent 98: 6th International Conference on Air Distribution in Rooms, held June 14-17 1998 in Stockholm, Sweden, edited by Elisabeth Mundt and Tor-Goran Malmstrom, Volume 2, pp 259-266, 4 figs, 2 tabs, refs.

Full scale tests under isothermal conditions were conducted in a mock up of a bath room with volume 7.1 m3. Standard decay technique employing active tracer gas technique was used to record the local mean age at 5 cm, 50 cm, 100 cm and 200 cm above floor in the middle of the room. Two kinds of blocking elements were used. One type of volume

0.5 m3 which resembles a cupboard. One, two and four of this cupboard like blocking elements were used. In the final tests 43 studs wedged between floor and ceiling were used to mimic a continuos distribution of blocking elements. For each configuration tests were conducted at the ventilation flow rates 5 Us, 10 Us and 15 Us. The corresponding Reynolds numbers are 7.8 103,15.8 103 and 23.6 103.

The intake of the air was located at the upper part of the door. The extract of the air was located at the ceiling level. At the lower flow rates there was a pronounced effect of the blocking increasing the time for the air to reach to different parts of the bathroom.

mixing ventilation, air exchange efficiency, full scale experiment, tracer gas

#NO 12092 Comfort problems and energy losses at shop entrances - field investigations and numerical simulations.

Schaelin A

Sweden, Stockholm, KTH Building Services Engineering, 1998, proceedings of Roomvent 98: 6th International Conference on Air Distribution in Rooms, held June 14-17 1998 in Stockholm, Sweden, edited by Elisabeth Mundt and Tor-Goran Malmstrom, Volume 2, pp 335-342, 13 figs, 2 tabs, 5 refs.

In order to give some guidance for the optimisation of shop entrances regarding comfort and energy savings, a project was launched by the City of Zurich. The project covers field investigations in 12 shops with different entrance types, and analytical and numerical investigations (CFD) for complementary results.

The emphasis of this work was on the interaction between the situation at the entrance for different technical local solutions with other factors of importance like building ventilation, building tightness and combination with other entrances. As a main result for the practitioner, a lot of recommendations can be drawn from these investigations and will also serve as the basis for governmental guidelines.

air curtain, air flow pattern, thermal comfort, cross ventilation, natural convection

#NO 12120 Transition from bi-directional to unidirectional flow in a doorway.

Blomqvist C, Sandberg M

Sweden, Stockholm, KTH Building Services Engineering, 1998, proceedings of Roomvent 98: 6th International Conference on Air Distribution in Rooms, held June 14-17 1998 in Stockholm, Sweden, edited by Elisabeth Mundt and Tor-Goran Malmstrom, Volume 2, pp 539-546, 7 figs, 1 tab, refs.

The air flow in a doorway is governed by density difference caused by temperature difference and pressure difference caused by mechanical ventilation. Tests have been carried out in a unique indoor test house where the room to room to temperature difference could be controlled very accurately with a new control system. In addition to these tests some tests were carried out in a scale model with water as the operating fluid. Two main criteria of unidirectional flow in a doorway have been explored:

1a. The recorded mean velocity is unidirectional.

1b. The neutral height is equal to the height of the door.

2 Unidirectional flow in the sense that there is not transfer of contaminant from one room to another.

To explore condition one, the velocity profile in the doorway have been recorded by transgressing the door opening. Condition two has been explored by using tracer gas technique.

air flow pattern, air velocity, convection flows, full scale experiments, tracer gas

#NO 12122 Experimental study of mixing in a closed room by doorway exchange flows.

Gladstone C, Woods A, Phillips J, Caulfield C

Sweden, Stockholm, KTH Building Services Engineering, 1998, proceedings of Roomvent 98: 6th International Conference on Air Distribution in Rooms, held June 14-17 1998 in Stockholm, Sweden, edited by Elisabeth Mundt and Tor-Goran Malmstrom, Volume 2, pp 555-561, 5 figs, 1 tab, refs.

We present a series of analogue laboratory experiments of the transient exchange flow between a room filled with warm air and a cold exterior following the opening of a doorway. Our experiments suggest that the time-scale for mixing the fluid in the room below the top of the doorway is independent of the door height. We then describe the steady-state two-layer stratification that is established when, in addition to the exchange flow, a localised heat source provides heat at the base of the room. Our experiments suggest that the height of the steady interface depends primarily on the aspect ratio of the doorway and is independent of the strength of the source of heat.

air change rate, air flow, mixing ventilation

#NO 12294 A measurement of the thermal performance and air distribution of indoor sports ground using swirling flow type natural ventilation system.

Sakai K, Ishihara O, Nagano S

UK, Garston, BRE, 1999, proceedings of Indoor Air 99, the 8th International Conference on Indoor Air Quality and Climate, and the Air Infiltration and Ventilation Centre (AIVC) 20th Annual Conference, held Edinburgh, Scotland, 8-13 August 1999, Volume 4, pp 358-363.

This report describe the thermal performance and air distribution of a Kumamoto prefectural indoor sports ground in Japan. The swirling flow type natural air ventilation system was adopted in combination with environmental symbiotic technique, and attempts were made to positively harmonise the system with the environment. In the measurements, emphasis was put on the identification of thermal environment and on the verification of the swirling flow type natural air ventilation system. From the measurements, it was confirmed that, by adjusting the opening of the doors on the lower portion of the outer wall in the indoor sports ground, airflow characteristics within the sports ground can be controlled, and it is possible to generate swirling flow without relying on mechanical force, and that comfortableness is improved on the audience seats in the swirling flow air ventilation, while comfortableness on the sports ground is increased in the intra-ground air ventilation.

thermal performance, natural ventilation

#NO 12300 Error estimation of blower door measurements by computer simulation.

Geissler A

UK, Garston, BRE, 1999, proceedings of Indoor Air 99, the 8th International Conference on Indoor Air Quality and Climate, and the Air Infiltration and Ventilation Centre (AIVC) 20th Annual Conference, held Edinburgh, Scotland, 8-13 August 1999, Volume 4, pp 827-832.

Computer simulation of building airtightness measurements shows the effect of changes in pressure distribution across the building envelope due to wind force and temperature difference on measurement accuracy. The wide range of leakage distributions, wind directions and velocities considered give information on the boundaries of these uncertainties. For wind velocities on site of ( site(3m/s, the additional uncertainty in the flow rate at 50Pa (Q50) found is comparable to the uncertainty due to standard pressure gauges or operator (about 3%). The additional uncertainty for on site wind velocities of no more that ( site(4,7 m/s is in the range of 7%. This is comparable to overall uncertainty in calm conditions. Unfavourable building location, leakage distribution and unlucky choice of external pressure taps can lead to significantly larger uncertainties in the measured flow rates of 10% for on site wind velocities of 3 m/s up to 40% for on site wind velocities of approx. 4.7 m/s, though.

computer simulation, measurement technique

#NO 12332 Deeltjes in OK na openen deuren. Pollutant flow through open doors in operating theatres.

Ham P J

Netherlands, TVVL Magazine, no 6, 1999, pp 26-30, 6 figs, 6 tabs, 4 refs.

Especially in the operating room there is much misunderstanding about the contamination risks when opening doors during surgery. This aspect is nearer illustrated with the results of an investigation recently carried out in the clean room of TNO Building Research at Delft NL. For this purpose the room was specially equipped as an operating room. The exchange of particles was defined when a person with usual circulation clothing is coming and going through sliding or right or left turning revolving doors. By means of 15 laser particle counters it was established where the particles coming from an adjacent air lock turn up. The clean room was fitted up for this purpose with a laminar downflow system with two operating lamps. Four electrical heated mannequins were placed around the table, representing the operating team; a fifth electrical heated mannequin was lying on the table as a patient. The exhaust of air took place by means of 8 high and low positioned air grids in the edges of the room. The powered operating lamps were placed in different positions to define their influence.

It appears that the downflow system with an air supply speed of 0.3m/s gives a very good protection of the wound area. A table of instruments placed besides the table and behind the operating team is strongly contaminated. A table of instruments placed at the foot of the table is good protected against incoming particles.

operating theatre, hospital, door opening, clean room

#NO 12352 Air quality and ventilation rates in school classrooms I: air quality monitoring.

Lugg A B, Batty W J

UK, Building Serv Eng Res Technol, Vol 20, No 1, 1999, pp 13-21, 13 figs, 6 tabs, 11 refs.

Indoor air quality was monitored at two schools in Essex, UK (located on the same site) during the week 3 - 7 November 1997. The objective was to determine whether the ventilation rates within the building were adequate to provide acceptable air quality to the occupants. Airborne carbon dioxide concentration was determined using continuous infrared detectors. A class base in each school was monitored for a two-day period. Occupancy patterns and window/door opening were observed during the first day of each period. Air temperature was also recorded. Indoor carbon dioxide levels exceeded those recommended for acceptable indoor air quality for a large proportion of the occupied period. Fresh air ventilation rates were below recommended guidelines.

carbon dioxide concentration, air change rate, window opening behaviour

#NO 12551 Numerical simulation of transient effects of window openings.

Fracastoro G V, Perino M

Australia, CSIRO and the University of Sydney, and IEA Energy Conservation in Buildings and Community Systems (ECBCS) Annex 35, 1999, proceedings of Hybvent Forum '99, First International One-Day Forum on Natural and Hybrid Ventilation, held at the University of Sydney, Darlington, NSW, Australia, 28 September 1999, Supplementary Papers, 11 figs, 2 tabs, refs. 

The simulation of room airing (ventilation by means of door/window opening) by means of CFD techniques requires a specially skilled user, because a number of difficulties arise since the first stage of simulations development, when the user is asked to choose the calculation domain and the time step, and choices which in principle appear correct may frequently lead to meaningless results.

This work is centred on the 2D, transient analysis of a single side enclosure where the ventilation is only due to temperature differences. Wind effect has not been taken into consideration. Different runs have been performed varying: boundary conditions, window sizes and calculation domains. Field model results have been compared to lumped parameter and zone model analyses. A check ono conservation principles has shown that CFD results are affected by noticeable inaccuracies for what concerns the prediction of both air temperature and ach's, which may be partially overcome re-scaling the time dependence of the phenomenon.

numerical modelling, window opening

#NO 12566 Protocol for field testing of tall buildings to determine envelope air leakage rate.

Bahnfleth W P, Yuill G K, Lee B W

USA, ASHRAE Transactions, Annual Meeting 1999, Seattle, 12 pp, 6 figs, 6 tabs, refs.

The objective of this project was to develop a relatively simple, accurate method for testing the overall envelope leakage rate of tall buildings. Two fan pressurisation test techniques, the floor-by-floor blower door method and the air handler methods, were developed and tested on two buildings. Criteria for conducting accurate tests were developed, including limitations on outdoor air temperature and wind speed. The floor-by-floor blower door method permits isolation and is difficult and time-consuming to apply. The air-handler method uses building air distribution fans for pressurization. It is most easily applied on a system-by-system level rather than floor-by-floor. Fan airflow techniques including orifice plate, pitot traverse, and tracer gas dilution were considered. The tracer gas method was found to be relatively easy to apply and highly accurate. Fan airflow rate measurement uncertainty by tracer gas was estimated to be 5.4% to 8.8% for the cases considered, assuming a 5% uncertainty in interzonal leakage.

air leakage rate, building envelope, tall building

#NO 12771 Genauigkeit der Blower Door-Messung. Der Einfluss von Aussenklima parametern. Accuracy of blower door measurements. The influence of outdoor climate parameters.

Weier H

Germany, HLH, Vol 51, No 4, April 2000, pp 42-49, 6 figs, 10 refs, in German.

The blower door is a simple to use measuring instrument for establishing the tightness of building envelopes. The accuracy of the measurement depends to a great extent on the prevailing conditions at the time of the measurement. The size of the errors which arise as a consequence cannot be precisely measured. A possibility for the calculation of the size of the errors is put forward in this article. Describes key recommendations for the procedure.

blower door, measurement technique

#NO 12775 Ventilation impact of a solar chimney on indoor temperature fluctuation and air change in a school building.

Khedari J, Boonsri B, Hirunlabh J

Energy and Buildings, No 32, 2000, pp 89-93, 9 figs, 2 tabs, 10 refs.

The aim of this research was to investigate, experimentally, both the feasibility of a solar chimney to reduce heat gain in a house by inducing natural ventilation and he effect of openings (door, window and inlet of solar chimney) on the ventilation rate. The study was conducted using a single-room school house of approximately 25m3 volume. The southern wall was composed of three different solar chimney configurations of 2 m2 each, whereas, the roof southern side included two similar units of 1.5 m2 each of another solar chimney configuration. Those configurations were built by using common construction materials. Experimental observations indicated that when the solar chimney ventilation system was in use, room temperature was near that of the ambient air, indicating a good ability of the solar chimney to reduce house's heat gain and ensuring thermal comfort. The air change rate varied between 8 - 15. Opening the window and door is less efficient than using solar chimneys, as temperatures between room and ambient was higher than that obtained with solar chimneys. 

natural ventilation, school building, tropical region, field testing, thermal comfort

#NO 12776 Analysis of wind-induced internal pressure in enclosures.

Miguel A F, Silva A M

Energy and Buildings, No 32, 2000, pp 101-107, 15 figs, 2 tabs, 13 refs.

A mathematical approach is developed for the dynamics of wind-induced pressures within enclosures. The model is based on the equations of mass conservation and motion, and the state equation of gases. It takes into account the characteristics of leakage paths of enclosure, the volume and flexibility of the enclosure envelop and objects within the enclosure. A sensitivity study is performed to examine the influence of these parameters on the dynamics of the internal pressure. 

pressure, dynamic response, opening; window, door, modelling

#NO 12946 Characterisation of natural convection in a room communicating with the outside environment through a door.

Carvalho M G, Ramos J E, Pitarma R A

in: PLEA '99 "Sustaining the Future - Energy, Ecology, Architecture", proceedings of a conference held Brisbane, Australia, September 22-24, 1999, edited by Steven V Szokolay, published by PLEA International, in conjunction with the Department of Architecture, The University of Queensland, Brisbane, Volume 1, pp 477-482, 4 figs, 1 tab, refs.

The present paper describes a numerical method for analysing three dimensional natural convection in rooms connected to the outside through large openings. The calculations made use of a Computational Fluid Dynamics (CDF) procedure which solves the three-dimensional equations for the conservation of mass, momentum and thermal transfer and air flow turbulence.

The CFD predictions agree with the experimentally observed features of the flow field, including the vertical air temperature stratification, with a reasonable degree of accuracy. 

door, opening, numerical modelling

#NO 12992 Comparative ventilation systems tests in a mixed climate.

Holton J K, Beggs T R

in: ASHRAE Annual Meeting 2000, proceedings of a conference held Minneapolis, USA, June 24-28, 2000.

A lab house constructed in Pittsburgh has been used as a site for the comparative evaluation of several ventilation systems. The house was built to relatively high performance standards and is representative of the type of house that would be a candidate for a purposely designed ventilation system. The systems installed and tested were (1) supply fan, (2) exhaust fan, (3) heat recovery ventilator, (4) balanced flow fan, and (5) open pipe to the RA plenum. A number of operational variations were tested with these systems: (1) central HVAC fan off/on/autocycling, (2) internal house doors open/closed, and (3) passive relief vents open/closed. The house was set up for continuous STEM test measurements from November 19, 1997, to January 8,1998. These tests included (1) overall house UA under each ventilation approach, which yielded a measure of the thermal impact of a system; (2) system operating power; and (3) overall house ACH measurement, yielding an indication of ventilation effectiveness. This paper will present an evaluation of these tests with conclusions concerning the relative performance merit of the five systems in the lab house.

ventilation system, test house

#NO 12996 Air leakage through automatic doors.

Upham R, Yuill G K

in: ASHRAE Annual Meeting 2000, proceedings of a conference held Minneapolis, USA, June 24-28, 2000.

A method had been developed to estimate the air leakage through high-use automatic doors. Two studies were carried out: one was a laboratory study of the discharge coefficients of doors of various geometries; the other a field study of the times for which automatic doors are open, as a function use. An airflow coefficient that is a function of the number of people using a door each hour is developed. The designer can use this coefficient with the pressure difference across the door to estimate the rate of air leakage through the door.

air leakage, door

#NO 13042 TOXFIRE: fire characteristics and smoke gas analyses in under ventilated large scale combustion experiments. Storage configuration tests.

Lonnermark A, Blomqvist P, Mansson M, Persson H

Sweden, Swedish National Testing and Research Institute, Fire Technology and Chemical Analysis, SP Report 1996:46, 60 pp.

This report describes combustion experiments performed in a 256 m3 test enclosure, large enough to allow the samples to be burned in a real size storage configuration. The materials studied were, as in the ISO 9705 room test series, polypropene, Nylon, chlorobenzene, chloro-nitro-benzoic acid and tetramethylthiuram monosulfide. A special instrument, a phi-meter, was built and used to measure the equivalence ratio, a measure of the degree of ventilation. The objective of these tests was to explore the influence of the combustion configuration on the fire characteristics, in particular on the nature of the combustion products. The solid samples were put in paper bags placed in cardboard boxes. Chlorobenzene, and polypropene in an additional comparison experiment, were burned in the ordinary open fuel pans. The door opening was kept the same in all of the storage configuration experiments, equal to the largest of the ISO room test openings. Heat release rate was evaluated from the production rates of CO, CO2, soot and unburned hydrocarbons. FTIR was used for online measurements of the concentrations of most of the low molar mass species in the smoke leaving through the door opening, chemiluminescence for the nitrogen oxides. Adsorbents were used for the sampling and subsequent analysis of medium size organics. Under-ventilated conditions were formally not achieved in these combustions. A model developed for calculation of the flow through the door opening allowed the evaluation of yields of the various compounds in the smoke from the concentrations measured. The resulting yields indicate that the combustions were, in fact, in part under-ventilated in spite of the measured phi values.

fire, smoke movement, industrial building, toxic material, modelling, combustion products

#NO 13065 Modeling contaminant exposure and indoor air quality in a single-family house.

Huang J, Chen Q

UK, Air Infiltration and Ventilation Centre, proceedings of "Innovations in Ventilation Technology", 21st AIVC Annual Conference, held The Hague, Netherlands, 26-29 September 2000, paper 15.

In this study, computational fluid dynamics (CFD) and a variety of mixing models is used to evaluate the indoor air quality in a small single-family house. CO2, CO, NO2, formaldehyde (HCHO), and vapor are tracked throughout the house to determine the concentration levels, occupational dosing, and personal exposure for a family of two adults and two children. Variations in metabolic activity, smoking, gas stove cooking, and showering make exposure very dependent on the individual's location in the house due to pollutant migration. Door positions have a significant role in exposure, where the comparative difference in exposure may be as much as 38%. The mixing models predict the average exposure of contaminants within approximately 30% of the CFD models, but the nuances of the flow pattern are not easily observable.

residential building, modelling, indoor air quality

#NO 13099 Ventilation performances in French dwellings: results from field observations and measurements.

Guillot K, Litvak A, Kilberger M, Boze D

UK, Air Infiltration and Ventilation Centre, proceedings of "Innovations in Ventilation Technology", 21st AIVC Annual Conference, held The Hague, Netherlands, 26-29 September 2000, paper 50.

This paper presents a recent field measurement study undertaken in 1999 on 73 recently built French dwellings. The study presented the opportunity to assess the conformity and the performances of the dwelling ventilation systems and to assess the impact of infiltration on air change rates. The following aspects were analyzed: (1) the type of ventilation facilities in the dwellings ; (2) the defaults in the installed systems and in their operation ; and (3) the measured air flow rates, as compared to the French standard required levels. For each dwelling, we investigated the infiltration air exchange contribution as compared to the total air change rate. For this, on site depressurization tests were performed on each dwelling with the ® blower door ¯ technique. With a first measurement, we assessed the sole air leakage rate, while with a second test, we measured the total air change rate (including air flow through ventilation air inlets). Comparison of results led us to assess the infiltration air contribution into the total air exchange rates. The results of the study show a significant proportion of defaults in ventilation systems, in terms of conformity as well as in terms of global performance. In addition, airflow rate assessments reveal a significant contribution of air infiltration when compared to the total air change rates. 

field measurements, infiltration, ventilation, residential building


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