COMPARATIVE ANALYSIS OF A PASSIVE AND ACTIVE DAYLIGHT REDIRECTING BLIND IN SUPPORT OF EARLY STAGE DESIGN

Abstract

A simulation case study is performed for a high-performance multi-storey open-plan doubleperimeter zone office building in Golden, USA (40°N, 105°W) to compare the relative daylighting illuminance performance of passive and active daylight redirecting blinds. Key design parameters such as location/climate, glazing properties, building depth, facade orientation, window to wall ratio, and window head height are tested in different configurations to examine their effects on the daylighting illuminance in the office space. The spatial daylight autonomy metric sDA300/50, defined as the percentage of the illumination analysis points in a space for which the daylight autonomy threshold of 300 lx is attained for more than 50 % of all hours between 08:00 and 18:00, is used to evaluate the annual daylight illuminance sufficiency over the floor area. Since the emphasis in this study is on providing early design stage support, a simplified radiosity model (calibrated with data collected on site) is used which yields an accuracy that is within the range of the uncertainties normally encountered in this early stage of the design process. The results show that for most of the combinations tested, the active blind performs as well as or better than the passive blind. Keyw ords: daylight redirecting blinds, spatial daylight autonomy, early stage design, openplan office space, perimeter zone