Global window film is constructed with ultraviolet-stabilized, dyed polyester which blocks up to 99 percent of the ultraviolet energy that is harmful to humans and damaging to fabrics and furnishings. However, ultraviolet energy is only one of the factors that contribute to fading. It is estimated that ultraviolet is responsible for roughly 40 to 60 percent of fading. Solar heat and light energy also contribute to fading, as do humidity, moisture, abuse and the quality of some dyes used in fabrics. Since these factors vary for different types of films and materials, the fade reduction benefit will also vary depending on the type of film selected, the quality of the products being protected and the environment.