Daylight performance of toplighting: An overview

Novel and advanced daylighting strategies and systems can noticeably decrease artificial lighting consumption and considerably improve light quality in the interior environments. In modern architecture, employment of rooflights is prevalent since they transmit daylight into deep plans or spaces lacking facade. Although, the use of this system is more common in temperate and cold climates, because of its severe thermal effects, it can be used in all the climates by innovative design strategies. Proper design of rooflights can significantly reduce energy use of lighting, heating, and cooling. Accordingly, the present study was designed to present an overview of toplighting field surveys conducted between 1984 and 2021. In this review study, analytical methods, efficient design parameters, and their effects on daylight and energy performance of the rooflights were investigated. These parameters include rooflight and indoor environmental conditions. Reviewed studies have utilized various methods such as analytical formulae, computer simulation, and experimental designs to investigate performance of the rooflight. The key point is finding or designing a proper state of toplighting in order to increase energy efficiency of the building while improving visual comfort. Also, studying effective rooflight design parameters presents practical guidelines for future studies.