Controlling building energy use by Overall Thermal Transfer Value (OTTV)

Overall Thermal Transfer Value (OTTV) is used as a control parameter for bu ilding energy use in the Hong gong Special Administrative Region (HKSAR). H owever, there are several approaches to determining the OTTV that produce q uite different results. Four different methods for calculating OTTV are bri efly reviewed and their formulation clarified in this paper. They are (1) t he equations derived by Chow and Chan through extensive energy simulations, (2) the ASHRAE 90A-80 method, (3) the one recommended in the Hong gong Cod e of Practice (HKCOP) published by the HKSAR Government, and (4) the basic definition of OTTV using data generated from computer simulations by TRACE 600. The OTTV of building envelopes is analyzed by studying the energy use of single-zone buildings with volumes varying from 4000 to 40,000 m(3). Res ults of OTTV calculated from the four methods are compared and discussed. M ethod (1) is the simplest and easiest one to apply, and the results are fou nd to be close to those simulated by computer programs. Finally, new approa ches to total building energy control are described for consideration in th e next revision of building energy codes. (C) 2000 Elsevier Science Ltd. Al l rights reserved.