Estimation of average daylight factor under obstructed CIE Standard General Skies

Recently, the CIE has adopted a range of 15 standard sky distributions covering the whole spectrum of usual skies found in nature. In a dense urban region, the external environment plays a significant role in daylighting designs. This paper studies an approach to calculating the average daylight factor for rooms facing heavily obstructed environments under overcast and non-overcast skies. The modelled vertical sky components under the various unobstructed and obstructed CIE Standard General Skies were determined. The performance of the proposed method was evaluated against the results obtained by computer simulations. The proposed approach provides a simple alternative for comparing daylighting designs for buildings facing different obstructed environments under various sky conditions.