Assessing the energy saving potential of anidolic system in the tropics

Employing the edge-ray principle, the anidolic system (AS) has been proven as a promising daylighting solution for various climates. However, studies on the thermal performance of an AS are still rare. Because of the dominant contribution of the space-cooling load to building energy consumption at the operational stage in hot climates, knowledge of the impact of AS application on the space-cooling load is important. This study assessed the energy-saving potential of AS in the tropics by measuring the daylight level and distribution, as well as the solar heat gain, based on Radiance and EnergyPlus simulations using weather files of two locations in the tropics—Yogyakarta and Singapore. Monitoring data of a full-scale, unoccupied test building was acquired to validate the Radiance simulations and EnergyPlus models. A comparison between the energy-saving potential for lighting and cooling of AS and conventional aperture models showed that the application of AS in the tropics benefits the daylighting performance (DF ≥ 3% and horizontal distribution 51–70%), but still produces higher solar heat gains (44–437% higher than those of clerestory only). Narrow anidolic collectors with medium angular spread (45°–52°) and maximum clerestory height equipped with internal shelves can be applied to produce lower solar heat gain or indoor air temperature (2%) with sufficient daylight levels (≥ 2%) and an increased in horizontal illuminance distribution (> 57%).