MORE | Spring 2022

Radiative Sky Cooling from Visibly Transparent High-Emissivity Glass Window

While natural light is desired for buildings, unwanted heat is simultaneously gained through windows, which burdens the building energy consumption for cooling, in particular, during the hot summer in Phoenix. This project studies the radiative sky cooling effect of a visibly-transparent high-emissivity glass window in a combination of outdoor testing and heat transfer analysis. The window is coated with dual layers consisting of commercially available polyvinyl fluoride film and indium tin oxide on a soda-lime glass substrate. The passive cooling effect is achieved by its unique selective radiative properties with high visible transparency, high reflectivity in near-infrared to reject the solar heat, and high emissivity in the mid-infrared to dissipate heat to outer space via the radiative sky cooling effect. The cooling performance of this window is analyzed by measuring the effect on indoor air temperature in scale model buildings.