Utilization factors for internal heat gains have been derived from an hour-by-hour computer simulation using actual weather data for 11 Canadian locations. These utilization factors are expressed as a function of the ratio of seasonal total internal gains to seasonal total reference loss for three daily profiles of internal gains and four levels of thermal storage. Curves are presented for conditions of constant room temperature and for allowable temperature rises of 2.75 and 5.5°C. For houses with a ratio of internal gains to reference heat loss of less than 0.4, all internal gains can be utilized to offset thermal losses. In addition, the application of the utilization factor method is extended to calculation of heating energy requirements of other buildings such as apartments, schools, and offices.

Units: SI