An OTTV-based energy estimation model for commercial buildings in Thailand

The use of OTTV as a measure of average heat gain across the building envelope of an air-conditioned commercial building has been accepted since it was introduced into Thailand and other ASEAN countries. Other studies have concluded that the average zone cooling coil load of an air-conditioning system can be taken to comprise the sum of the average external load, internal loads, and terms representing the storage effects of the exterior wall and internal masses of the building components in that zone. This conceptual relationship is used as the basis for postulating an equation that linearly relates the cooling coil load of a building zone over a period to its external factor represented by the OTTV and its internal factors represented by all internal loads over the same period. It is also used to postulate an equation that relates the energy use by the building to the cooling coil load and the direct loads. This study utilizes DOE-2 simulation program in a series of parametric runs to develop an OTTV formulation each for four types of commercial buildings. The resulting OTTV formulations were used in further parametric runs to develop a formulation each for the cooling coil load and for energy use in the form postulated. The formulations are validated using field audit results.