Evaluation of Simplified Procedure for Indoor Daylight Illuminance Determination against Data in Scale Model Measurements

An accurate estimation of the amount of daylight entering a building is the key step in evaluating daylighting designs. The concept of the daylight coefficient (DC), which considers changes in the luminance of the sky elements, offers an effective way of computing indoor daylight illuminances under various sky conditions and solar positions. We currently propose a numerical procedure in the form of nomograph to compute the interior daylight illuminance using the DC concept. This paper presents the work to validate this method via scale model measurements under different actual sky patterns. It was shown that daylight illuminances calculated by the proposed method were in reasonably good agreement with measured results. The findings will hopefully provide building professionals and students with a reliable and simple alternative to current practices that incorporate sky luminance variations to predict the indoor daylight illuminance and assess visual performance under various real sky conditions.