Window Film Basics: What It Is and How It Works

https://yenkee-wiki.win/index.php/The_Basics_of_Solar_Heat_Gain_Coefficient_and_Window_Film_57949

Window film sits on the inside of glass, a thin laminate that changes how a window behaves without altering the frame or structure. It is a simple concept with a surprising range of implications for comfort, energy use, and daytime privacy