Evaluating an indoor daylight illuminance calculation tool against full-scale measured data

The determination of daylight illuminance in internal spaces is a key issue in daylighting analysis. The recently introduced concept of the daylight coefficient (DC), which considers changes in the luminance of sky patches, provides an accurate way for calculating indoor daylight illuminance under various sky patterns and sun positions. This paper proposes a simplified numerical procedure to estimate interior daylight illuminance using the DC concept. The paper presents an evaluation of the new method via full-scale field measurements under different sky conditions. The findings indicate that the daylight illuminances obtained by the proposed approach were in agreement with measured readings. The simple nature of the proposed method offers building professionals and students a reliable and convenient alternative to extensive calculations that incorporates sky luminance variations to predict the daylight illuminance and assess visual performance under various sky conditions. © 2006 University of Sydney. All rights reserved.