The ASHRAE crack and air change methods (1) for estimating infiltration heating load are probably adequate for sizing of heating systems, but are not suitable for carrying out hourly energy analysis of buildings. As the infiltration load is a significant component of the overall heating load, there·is a need for a method that is easy to use, but takes into account all of the significant factors that determine the rates of air infiltration.

During 1960-1962, DBR/NRC conducted air leakage measurements on two single-story houses (2) built during the nineteen fifties using the tracer gas technique. It was followed several years later in 1967-1968 by the measurement of the air leakage characteristics of their enclosures using the house pressurization technique (3). The results of these tests on the two houses were used to develop a procedure for calculating infiltration rates similar to the one, recently developed for high-rise buildings (4). Also, research needs were identified so that the calculation procedure can be applied to houses of different design, construction and wind exposure.

A computer model (not the subject of this paper) for houses with oil furnaces was also developed by DBR/NRC which complement this study (5).