Abstract
The rate at which heat is transferred through the earth is a phenomenon that affects the environment. In arid and semi-arid areas environmental weather changes show temperature ranges of more than 15 degrees. The nature of substrata or subsurface soil determines the temperature variations at any given time of the day. Gain and release of heat are generally slow but mainly dependant on the constituents of the ground. It is believed that clay content of backfill material can be a significant factor to control temperature during evening and early morning times. Investigations of heat gain and release including temperature changes were studied for soils commonly used. Range of optimum clay content associated with convenient evening weather will are highlighted.