Assessing the allowable daylight illuminance from skylights in single-storey buildings in Malaysia: a review

A skylight system casts uniform levels of natural light over an area with minimum obstruction either internally or externally. In tropical climates, especially near the equator, the levels of solar radiation and conditions of sky appearance represent the main limitation in this region. In Malaysia, the application of skylight systems to single-storey buildings is limited because of environmental constraints that discourage its adoption. Understanding the allowable level of daylight in an indoor environment is crucial. Many standards, guidelines, and studies have provided various levels, but the desired level is still under debate. Therefore, this research aims to review and evaluate the allowable useful illuminance of daylight in the indoor environment from a skylight in single-storey buildings (used for office work) under Malaysian sky conditions. This study provides a comprehensive review of previous research on understanding daylight illuminance and Malaysian sky conditions. Based on this comprehensive review, a new level of daylight illuminance for skylight needs to be adopted to achieve better visual comfort and consequently decrease energy usage load in a variety of buildings in the tropics.