Space-age energy saving, carbon emission mitigation and color rendering perspective of architectural antique stained glass windows

This article explores optical and thermal characteristics of different colored stained glasses extensively found in historic religious architectures. Solar-optical and color rendering properties of glass samples were explored with spectrophotometry experimentally. Thermal analyses in cardinal and intercardinal orientations were performed to calculate the solar heat gains, building thermal loads, and daylight inflow through the stained glasses for different colored architectural antique stained glasses across two climatic zones (New-Delhi & Tiruchirappalli) of India for energy savings and daylight inflow. A numerical model verified using Design Builder simulations was used to conduct the thermo-economic analysis. Except for blood red and golden yellow samples, whose color rendering metrics (CRI) was below the minimum allowed level in the standard (80), the measured CRI of studied stained glass samples was in the range of 80.15–87.31. For temperate and hot climates, the Olive-green stained glass showed the highest heat gain reductions of 44.85% and 45.42%, respectively, as compared to clear glass. Building operational costs were 20–45% lower with various stained-glass systems compared to clear glass for both climatic conditions. Olive-green stained glass had the highest cost savings of 13.02$/m2, carbon emission mitigations of 0.89tCO2/year along with adequate daylight inflow to avoid artificial daylighting.