Optimizing Window-to-Floor Ratio and Glazing for Daylight and Cooling in Tropical Educational Buildings: A Case Study in Chiang Mai, Thailand

In tropical climates, where cooling loads dominate building energy use, minimizing cooling demand is particularly critical for achieving carbon neutrality in educational buildings while maintaining adequate daylight and visual comfort. This study investigated the combined effects of the Window-to-Floor Ratio (WFR), Visible Light Transmission (VLT), and Solar Heat Gain Coefficient (SHGC) on building performance through parametric simulations using ClimateStudio. A university classroom in Chiang Mai, Thailand, served as a case study with a baseline configuration of 30% WFR and SHGC 0.82, which is representative of conventional tropical classroom designs. Twenty retrofit scenarios were modelled by varying the WFR (30%, 25%, 20%, 15%, and 10%) and VLT (88%, 77%, 66%, and 56%) with SHGC (0.82, 0.62, 0.53, and 0.61), respectively. Each scenario was evaluated for estimated CO₂ emissions from cooling energy intensity, surface solar exposure, spatial Daylight Autonomy (sDA), and annual sunlight exposure (ASE) using radiance-based daylight analysis simulations. Thermal simulations were not conducted; instead, solar radiation was used as a proxy for cooling demand. The results indicate that optimized configurations (e.g., WFR 20-25% with SHGC 0.53) lower surface solar exposure by over 40% and cooling-related CO₂ emissions by approximately 30% compared to the baseline, while maintaining high daylight availability (sDA ≥ 96%). This approach offers preliminary insights for facade optimization aimed at passive cooling and sustainable energy use, though it lacks the precision of dynamic thermal modeling and should be interpreted with caution. The findings support Sustainable Development Goals 7 (Affordable and Clean Energy), 11 (Sustainable Cities and Communities), and 13 (Climate Action), offering practical guidance for architects and engineers in designing climate-responsive, carbon-neutral educational buildings in hot-humid regions.