English

The significance of air tightness on building performance and the factors affecting the air leakage performance of the building enclosure are discussed. the ability of the ASTM standard air leakage test method to check the quality of design and manufacture of factory-assembled walls, windows and doors as well as the inability of the method to provide the building designer with quantitative air leakage data for calculating heating and cooling loads and designing smoke control means is also discussed.

Reports on the air leakage characteristics of the exterior walls of eight multi-storey office buildings in Ottawa. Results of the measurements taken are given and a method for calculating infiltration rates caused by stack action has been developed andis applied to heat loss calculations using the measured wall leakage values.

Describes portable air leakage apparatus capable of measuring the air infiltration of whole dwellings directly on site by the pressure method. Main assembly consists of a flow measurement duct and electric fan. Describes test procedure and gives air leakage curves for an ordinary semi-detached house and an experimental house. Finds that doors and windows account for a surprisingly small proportion of total leakage.

Part of an extensive research programme being carried out also in Denmark, Finland and Sweden. Describes 75 window tests and gives diagrams of air flow and rain penetration apparatus. Proposes tentative evaluation curves for air penetration of windows of a stringent kind suitable for a severe climate. For air pressure of 30-40 mm of water, an 'acceptable' air flow is about 30 m.m. per hour per test window, with 'good' at about 20 and 'excellent' about 11. The curves are shown graphically.

Proposes a method for measuring the rate of air change in factories using ammonia as a tracer gas and measuring its rate of decay by a colorimetric method. The advantage is that extremely small quantities can be detected. The method is cheap, easy to use, reasonably accurate and unobjectionable to the occupants.

Describes the influence on heat resistance of an insulated wall of workmanship and forced convection. Compares experimental investigations on cross-bar walls with calculated values. Examples show the influence on heat resistance of insulation installation, air-flow along the insulation and air-flow through the insulation. Concludes that air-tightness of the vapour barrier and partly of the inside board are of great importance.

Ventilation rates in two test home were measured using helium as a tracer gas. Pressure differences across the exterior walls of the house were recorded using pressure taps. Gives results for air infiltration tests and the calculated air infiltration. Finds that during summer air infiltration rates varied approximately linearly with wind velocity. During the winter, the pattern and extent of air infiltration were influenced by both house stack action and furnace operation.

Gives theoretical discussion of the neutral zone in ventilation. Shows that the pressure difference tending to cause flow at any opening is proportional to the vertical distance of that opening from the neutral zone and that the amount of air that may be passed by a given opening is proportional to the square root of the vertical distance of that opening from the neutral zone.Discusses the position of the neutral zone in a building which is governed by the relative amount of opening at top and bottom and by the inside to outside temperature difference at different levels.

Reports investigation of air change rates in two residences using helium as a tracer gas. Gives results of measured air change rates, wind speed and direction and internal to external temperature difference. Uses statistical method to compare results from the two residences and concludes that temperature coefficients were statistically different but that wind coefficients were not. Finds high dependence of infiltration rates on indoor to outdoor temperature difference and that values for air leakage obtained from current methods of estimation were lower than those actually experienced.

Examines the use of radioisotope tracers to measure ventilation rates of simple and multiple enclosures. Discusses accuracy of the methods in relation to results obtained in an experimental room with controlled ventilation. Describes an instrument which measures ventilation rates directly, following release of aradioisotope tracer. Demonstrates its accuracy and operating advantages.