A simplified overall thermal transfer value equation for building envelopes

We describe a methodology for determining a simplified overall thermal transfer value (OTTV) equation for air-conditioned buildings in Singapore. The OTTV equation was formulated by modelling a generic commercial building and using results from DOE-2 computer simulations as a database of heat gains. The new equation increases the weight of the solar heat gain as compared to the currently used OTTV equation. This change yields an improved relation between the OTTV and the total heat gain through the building envelope.