Glazing for double skin facade

daylighting under different transmittance composition

Abstract

Over the years, the interest in double skin facades (DSF) has increased since it is a design solution offering buildings a modern and transparent appearance. They are well known for improving comfortable conditions for hot and cold climates. However, studies focusing on the incidence of daylighting in such systems, especially regarding the impacts of the materials applied to the DSF layers on the lighting penetration and distribution into the rooms are still few. Thus, this study aims to analyse the daylighting performance of different glazing transmittances applied to the inner and outer skins of an educational DSF building in southern Brazil (lat. 30º S). Analyses were performed considering two metrics: Spatial Daylight Autonomy (sDA_300/50%) and Annual Sunlight Exposure (ASE_1000,250h). Using Grasshopper and ClimateStudio Plugins for Rhinoceros 3D, simulations were carried out considering seven different types of glazing. The results demonstrated that the use of glazing with high transmittance promotes an increase in daylighting accompanied by an increase in the risk of visual discomfort. Furthermore, none of the simulated cases presented acceptable results for the sDA₃₀₀ and ASE₁₀₀₀ variables, but the most adequate results were found in the cases that used glazing transmittances of 16% and 53% on the outer and inner DSF layers, respectively. In conclusion, for middle latitudes, the use of high transmittance glazing should be avoided in the DSF. It can be useful if it is associated with a medium transmittance glazing applied to the inner layer.