ASHRAE OR-10-049

Abstract

<strong>INTRODUCTION</strong> <br>During the conceptual design stage of a building, the design team often has to make critical decisions with significant impact on the energy performance and indoor comfort conditions. The design and control of facades and fenestration systems has a major impact on building performance, especially for perimeter spaces of commercial and institutional buildings. With the growing interest in energy-conscious design and solar architecture, the importance attached to daylight utilization has grown; nowadays, daylighting is widely accepted as a necessity for commercial buildings. <br>Daylight utilization can improve lighting quality (Selkowitz 1998), increase occupants' productivity (Heschong 2002; Nicol et al. 2006) and effectively reduce electricity consumption for lighting (Lee et al. 1998; Tzempelikos et al. 2007). <br>Nevertheless, the balance between positive and negative impact of solar radiation on building overall energy performance and human comfort should be taken into account at the early design stage. Glazed facades often create problems such as glare, thermal discomfort and overheating. Peak heating and cooling loads could increase significantly, depending on the window size and properties, climate and orientationThe role of thermal mass is also critical (Balaras 1996). For all these reasons, many innovative fenestration and shading systems have been developed and studied in order to control solar gains, reduce glare and create a high quality indoor environment. Unfortunately, the optical and thermal properties of such systems are not usually provided by the manufacturers and they have to be estimated using experimental techniques (Rosenfeld et al. 2001; Andersen et al. 2005; Collins et al. 2001), using complex theoretical models (Pfrommer et al. 1996; Tsangrassoulis et al. 1996) or even advanced software (Reinhart and Walkenhorst 2001).