Measurement of heat gain to space and radiant/convective split from equipment in buildings is necessary in order to make accurate assessment of its impact on cooling loads. Recent advances in design of buildings and improvement on the thermal characteristics of insulation materials and building envelope systems have significantly reduced the cooling load from the external source; however, the addition of various office, laboratory and hospital equipment to the building has become a major source of internal cooling load. Unfortunately accurate information on the total heat gain from those equipment items is lacking in current handbooks.

Another factor affecting the cooling load calculation is the split between the radiant and convective heat gain from the equipment. The convection portion of the heat transferred from the equipment to the surroundings is an instantaneous load since it is added to room air by natural or forced convection without time delay, whereas the radiation portion is absorbed by the surfaces of the room and then dissipated over time.