Abstract

The purposes of this paper are to present the results of a study on all sky conditions for zenith luminance modeling and daylight availability for the central region of the Northeastern part of Thailand (16°14^'N, 103° 15^'E). The data for zenith luminance estimation were taken for one year from a station at the Mahasarakham University (MSU), the required components of sky quantities, namely, zenith luminance for saving energy used in buildings, are estimated. The zenith luminance models for all sky conditions are determined and developed to become a new function in the polynomial function. The accuracy of the validated model is determined in terms of the mean bias deviation (MBD), the root mean square deviation (RMSD) and the coefficient of correlation (R²) values. Comparison of the estimated zenith luminance values and the observed values revealed a small error slide as well. The estimated values of zenith luminance in daytime at Mahasarakham, Thailand is presented in terms of light source efficacy and integrated with electric lighting in commercial buildings that could reduce energy and power consumption.

Key words: Daylight, sky luminance, zenith luminance, solar energy.