Polycarbonate Glazing: Maximum and Effective Temperatures for Outdoor Weathering Exposure in the Desert of Arizona

We define an effective temperature (T_eff) as an irradiance-weighted average temperature of a material during weathering. It is the constant temperature that would give the same amount of damage as the sample sustains during natural cycling and serves as a benchmark for predicting lifetimes. It is weakly dependant on the activation energy (E_a) of the degradation process. The annual effective ambient and black panel temperatures at an Arizona test site were 30° and 42°C, respectively, for E_a = 4–7 kcal/mol. Privacy color polycarbonate minivan sunroof windows had surface T_eff = 45–46°C exterior, 54–58°C interior, and 49–52°C exterior blackout surfaces. Maximum recorded temperatures were 73°C, 87°C, and 81°C, respectively.