Effect of Daylighting Strategies on Building Cooling Loads and Overall Energy Performance

摘要

It has been demonstrated that daylighting, by reducing electric lighting requirements, is one of the most effective energy-conservation strategies in office building envelope design. Additionally, because the luminous efficacy of daylight outdoors is higher than that of most electric lighting systems, it is frequently assumed that buildings designed for daylighting will have smaller cooling loads than similar buildings not designed for daylighting. This assumption is valid only within certain specific design limits. Outside these limits, daylighting may increase cooling loads, requiring larger chillers and associated cooling equipment, and may seriously compromise or even negate the economic benefits of reduced electric lighting use. In this paper we discuss these limits, the luminous efficacy of delivered daylight in sidelighted and toplighted spaces, methods of enhancing efficacy, and the resultant overall energy and economic impacts of daylighting design. (ERA citation 11:022822)