LUMINOUS EFFICACY OF DAYLIGHT UNDER DIFFERENT SKY CONDITIONS

Daylighting is recognised as an important and useful strategy in terms of energy-efficient building design in hot climates. However, dayligh ting is always accompanied by unwanted solar heat gain, particularly d uring the cooling season. To achieve and evaluate daylighting design, solar radiation and outdoor illuminance data are needed. In 1991, a me asuring station was installed at the City University of Hong Kong to m easure global and diffuse solar radiation and outdoor illuminance. The measured data are analysed, and empirical models to determine luminou s efficacy under different sky conditions are developed and presented. Implications for energy efficiency in building designs are discussed. Copyright (C) 1996 Elsevier Science Ltd