Causes for Heat Transfer

Following are the factors which contribute for transfer of heat:

1. Value of thermal insulation of the exterior shell (e.g., external walls, roofs, etc.).
2. Difference in temperature between the outside and the inside. If the difference is greater; greater shall be the loss of heat.
3. Surface area of the building exposed at the external face. Evidently for greater area the heat transfer shall be more.
4. Surface areas of external windows and doors. For example, the heat transfer of a glazed window is about three times more than a typical wall construction.
5. Rate of air movement through any cavities in the enclosing structure. For example, air spaces through the roof or below a suspended floor may cause considerable heat transference.