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.

Notes principle of air change rate measurement using natural growth exponential equation to measure concentration of tracer gas. Experience shows that period required for satisfactory measurement is often periodicity of air change rate. Diagram relates linear and logarithmic scales used in air change equation. Describes use of pre-programmed gas analysis equipment allowing extrapolation to forecast results. Uses microprocessor for evaluation. Also discusses importance of instrument calibration.

Discusses current knowledge concerning wind-induced ventilation in buildings. states major difficulty in estimating ventilation and infiltration rates in a building is ignorance of wind pressure distributions around structures. Examines properties of wind with special reference to mean velocity profiles, characteristics of turbulence and wind energy spectrum. Reviews internal and external pressure distributions on an isolated building. Studies effect of grouping of buildings on pressure distribution around a house by considering results of wind tunnel tests.

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.

Presents infiltration model whose input is: 1) air leakage under fan pressurisation and 2) natural indoor/outdoor pressure differences. Output is the house's natural infiltration rate. Describes tests of model on 6 houses in usa, 3 conventional houses in a mildclimate region and 3 energy-efficient houses in a cold winterregion. Obtains good agreement between infiltration rates measured using tracer gas and rates calculated from the model.

Describes investigations in California with a mobile laboratory designed specifically for studies of indoor air quality and energy use in buildings before and after energy conservation retrofits and in new buildings incorporating energy-efficient designs. Among parameters measured are infiltration rate, content of CO, CO2, NO, NO2 SO2, O3, formaldehyde, radon, etc. Results of initial phase of program indicate that concentrations of some air pollutants in the built environment are higher than outdoor levels and in some cases exceed recommended health and comfort criteria.

Presents method for establishing conditions and an acceptance criterion for window air-tightness testing in relation to average energy (heating) saving per winter. Uses wind velocity data from israeli meteorological station of Ashdod to demonstrate difference between various methods of evaluating design wind velocity. Uses 41 different typical dwellings to determine unique criterion for acceptable air leakage under test conditions which ensures average of 1 air change per hour in most Israeli dwellings.

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.

After discussing briefly the principles of natural ventilation, goes on to describe tracer gas techniques, air movement measurements, and various model techniques including analogues. Advantages and disadvantages of each method are indicated, andtheir suitability for particular applications.

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.