A technique for evaluation of sky luminance distribution in tropical climate: a case study of Northeastern Thailand

Abstract

Sky luminance distribution (SLD) is an important index for building design. This article proposes an alternative technique for evaluation of sky luminance in a tropical climate without using a sky scanner. The SLD was calculated from the zenith luminance (Lz) and diffuse luminance (Dv). Four consecutive years record of Lz and Dv were used to generate all sky functions. The obtained sky luminance models were validated with the CIE-standard model. Accuracy indexes in terms of MBE, RMSE and R2 were presented. The obtained results indicated that MBE, RMSE and R2 were in the ranges of −16.02% to 5.92%, 4.56–21.46 and 0.96–0.99, respectively. It was suggested that the model proposed in this study would be an effective alternative method for measuring SLD.

Keywords

• sky luminance distribution
• sky luminance modelling
• gradation function
• indicatrix function