Effects of optical scattering in aerogel glazing system on daylight illuminance and discomfort glare

Abstract

Windows play a crucial role in daylight supply and visual comfort in buildings. Among advanced window technologies, aerogel glazing system (AGS) is distinguished by its superior thermal insulation. However, the optical scattering properties of AGS have rarely been addressed in previous simulations of daylight illuminance and discomfort glare. In this study, the optical scattering property of granular AGS with varying particle sizes and filling thicknesses was measured. The diffuse transmission of AGS was considered in the three-phase method based on Radiance to simulate the daylight illuminance and discomfort glare of AGS. Simulation accuracy was validated through an in-field experiment. The impact of haze on daylight illuminance and discomfort glare was further quantified. The results showed that the three-phase method, which accounts for the optical scattering properties of AGS, was found to be reliable. The relative mean bias error (rMBE) and the relative root mean square error (rRMSE) of the simulated horizontal and vertical illuminance, as well as daylight glare probability (DGP), were within 13 % and 4 %, respectively. Moreover, haze was found to significantly influence daylight illuminance and discomfort glare, particularly in sunny days. As haze increased from 0 to 1, the average horizontal illuminance at the front position in sunny days decreased by 6827 lx (≈61 %). Simplifying AGS as either conventional specular glass or a perfect Lambertian diffuser may lead to notable inaccuracies in simulation results.