HEATING and cooling load calculations are the primary design basis for most heating and air-conditioning systems and components. These calculations affect the size of piping@ ductwork@ diffusers@ air handlers@ boilers@ chillers@ coils@ compressors@ fans@ and every other component of the systems that condition indoor environments. Cooling and heating load calculations can significantly affect the first cost of building construction@ the comfort and productivity of building occupants@ and operating cost and energy consumption.