Introduction of a New Daylighting Quality Benchmarking Method

Daylighting regains its status in illuminating interiors in the wake of building sustainability. The trend of lighting research has turned back to improving indoor daylighting quality such that occupants would enjoy good task visibility and visual comfort. The daylight factor giving the daylight availability from a static overcast sky is the common method for daylighting assessment, but daylighting quality should be evaluated in a broader way and occupants' perception should be emphasized. This paper develops a daylighting quality benchmarking method based on the weights of importance of five decision factors previously identified by the authors and demonstrates the methodology used for determining a novel multi-criteria daylighting quality index (DQI) using real climatic data and computer simulations. An associated 5-star rating scale is also proposed for categorizing daylighting quality. The results show that cellular offices with small windows facing external obstructions would not have high star ratings and that increasing the window area and/or removing external obstructions would improve the DQI and star rating.