Describes wind tunnel measurements made on a model of a tall building surrounded by lower buildings under various combination of wind speed, wind angle and air temperature. Gives method for calculation of air infiltration rates and describes the computer program used. Concludes that air infiltration is a strong function of wind direction. Finds that maximum air infiltration was produced by a wind that approached at 0 deg and the minimum air infiltration occurred at 75 deg wind angle.
Suggests many ways of reducing outdoor air admitted to a building. Notes importance of measuring minimum air flow to ensure adequate ventilation. Suggests measuring the concentration of CO2 in indoor atmosphere and using the results to control incoming ventilation. Describes simple and inexpensive implementation of the technique.
Stresses importance of building draught-free housing to conserve energy. This poses problems for heating and ventilating engineer. Lists effects on microclimate. Explains interplay between freedom from draughts and ventilation. proposes a list of terms with definitions related to infiltration and draught prevention.
Reports pressurization tests on eleven schools both with the air handling system on and with it off. Obtains air leakage through components of the building by comparing overall leakage rates before and after sealing each component. Uses leakage rates to calculate air infiltration using a simplified model of a school building. Finds that infiltration caused by stack effect is significant even for a single-storey building.
States that application of further thermal insulation to house structures increases importance of ventilation heat loss, from around 20% to nearly 50% of total design heat requirement. Any further energy savings will be by minimising ventilation components. On basis of British Gas research results and others, illustrates sources and mechanisms of infiltration to give an insight into problems it may cause in future housing. Treatseffect of weather, ventilation rates. Among conclusions states increasing attention will have to be paid in future toinfiltration.
There is at present no analytical step-by-step procedure for calculating air infiltration into houses. Extracts useful house air infiltration data from almost 20 years of scattered research work. 1) Highlights important conclusions of these papers andgives some selected notes on the many variables involved. 2) Reduces this information and summarises it in 2 tables. sets out 2 worked problems using these tables to demonstrate their application.
Describes results of computer study of behaviour of 2 better insulated houses, one of rationalised traditional and one of timber frame construction. Compares their performance with a contemporary house. Provides most important results regarding mode of operation and effects of air leakage. Concludes that better insulation is effective energy conservation measure but heavyweight characteristic of insulated structures result in intermittent heating being a less attractive means of reducing heat demand. Air leakage, if not controlled, becomes animportant component of the total heat loss.
Describes sealing houses against air infiltration to allow controlled ventilation. Notes inherent risks in poor ventilation such as high radon content and its associated decay products, poor air quality, moisture, condensation, mould and allergy-producing dust particles. Treats requirements in swedish building code and stipulated minimum air change rate. Comprehensive series of graphs illustrates air change rate as function of wind speed and different grades of building air tightness.
Points worthy of consideration regarding air leakage, i.e. the causes, identification, problems and remedies are briefly discussed generally without technical details and some illustrations are given of problems. Air leakage is common in most buildings, but with increasing standards of performance and the trend to taller buildings, it is becoming less tolerable. Reference is made to other CBD reports in which details are specified. The positive control of air leakage can only be achieved by careful attention in design and adequate inspection during construction.
Discusses control from outdoors and gives a formula for the heat required to maintain indoor design temperatures. Outlines the twofold effect of wind, i.e. the increase in the heat transmission coefficient for outside walls, and increased ventilation and air infiltration caused by pressure differences. Explains the solar effect by formulating the heat load on the outer walls and through the windows. An example illustrates the calculation procedure. Tabulates the increase in heat consumption due to wind; this varies with wind speed, building location and height.
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