Internal heat gain in laboratory design can be the determining factor in room cooling load and air flow. The design of laboratory ventilation systems has strong theoretical support. ASHRAE methods of cooling load calculations are available for both computer or manual use, but all depend on the "experience and judgement" of the user. Investigates ways by which to optimise access to these methods and to highlight areas where more technical information is important for design. The digression into the technical features approaches the equipment usage factor, as well as the radiation vs. convection ratio of heat transfer from equipment. The equipment "use" factor and the "diversity" factor are analysed as subjective implications in the design process. However, more ASHRAE research is needed in the area of laboratory internal heat gains. Some suggested simplifications do not question the existing theoretical basis of the design, nor do they try to discourage the use of detailed calculations; rather, they aim to speed the design process without affecting the quality of the results.

KEYWORDS: year 1996, calculating, laboratories, equipment, components, cooling load, heat gain, air flow, heat flow, ventilation, designing, equipment providing heat, models