A residential structure is subjected to varying heating and cooling loads due to thermal energy exchanges with the surrounding environment. The loads arise from attics, the exterior envelope, air-infiltration, occupants, lights, and subgrade
losses. All of these loads were investigated in detail as a portion of an extensive research project (1). The particular emphasis of this paper is to present the research that was completed on subgrade heat losses. Subgrade heat losses can originate from crawl spaces and basements. Tne actual study completed was restricted to the heat loss from basements, but the procedures developed should be applicable to either.

The objective of the research was to develop a calculational procedure for determining the hourly heat loss through basement walls and floors below grade. The procedure was required to be general in nature so that different configurations could be analyzed. In order to develop and validate the procedure, a series of measurements were required. The measurements were completed on a residence for a full year.