Daylight availability assessment and its potential energy saving estimation –A literature review

Daylight has been recognized as a free energy and cost effective alternative to artificial lighting for sustainable building design. It could also provide a more pleasant and attractive indoor environment for its good color rendering and it matches the human visual response much better than artificial light source. The effects of daylight on the occupancy comfort, health, well-being and productivity are well acknowledged. However, despite the above advantages, daylight is not widely integrated with the artificial lighting in building design as there is lack of information and evaluation tools on the suitability of daylight and its energy saving potential. The procedure of evaluating the indoor daylight performance consists of two parts: one is to assess the indoor daylight availability by either simulation or field measurements; another one is to accurately estimate potential energy saving when sufficient daylight is provided. This paper therefore presents a review of metrics and methods for indoor daylight availability assessment, as well as estimation methods used for predicting potential energy saving from daylight. The aim of this paper is to provide building designers or operators some useful information so that more daylight schemes could be considered in sustainable building design.