Evaluating Glare in Leed Certified Buildings to Inform Criteria for Daylighting Credits

Extensive documentation has been developed to support the benefits of daylight for building occupants. Recently, the high performance building industry has shown a trend towards prioritizing better daylighting conditions. In response to this trend, the Leadership in Energy and Environmental Design (LEED) rating system now addresses daylighting and views as one of the criteria for compliance. However, effective daylighting has its challenges—most importantly addressing the issue of glare. This paper discusses the issue of glare and its relationship with requirements for effective daylighting within the criteria of the LEED rating system. In this study, a LEED certified building on Montana State University's campus was considered as a case study. This paper conducts an analysis by comparing the results obtained from compliance procedures for LEED with independent evaluations of glare using simulation and post occupancy evaluation surveys. This paper concludes that the ‘illuminance simulation’ option provided in the current version of LEED (LEED v4) for compliance does not adequately address the issue of glare. This paper provides recommendations to improve the LEED rating system for indoor environmental quality which include: the incorporation of glare assessment in the evaluation procedures of daylighting and views; the use of dynamic simulations that incorporate climatic conditions in the evaluation of daylighting; and evaluating glare in early stages of design by using simulation tools.