There are six factors affecting fabric fading:
Ultraviolet Light (40%)
Visible Light (25%)
Heat (25%)
Chemical Vapors (including ozone)
Age of Fabric
Dye Fastness
Clear single pane glass (1/8″ to 1/4″) will reject 23-28% of the ultraviolet light from the sun.  Insulated glass is slightly better, rejecting 36-41%.  Our Window film installed on glass rejects 99.9% of solar ultraviolet light. Different types of clear glass and window systems will reject 13-29% of the solar heat.  Our window film products, for example, will reject 82% of solar energy, which drastically reduces any hot spots. No window film can eliminate fading.  It can, however, offer maximum protection from fading caused by solar ultraviolet light, visible light and solar heat.