Assess: Window Film

Solar-control window films reduce solar heat gain by reflecting and absorbing solar rays. They help stabilize interior temperatures and reduce reliance on heating-and-cooling systems. That leads to lower monthly utility bills. Window films can be colored or clear and are usually applied to the glass surface of a window that faces a building’s interior. They block as much as 80% of solar heat from passing through windows and 99% of ultraviolet rays, which are harmful to skin and fade the colors of furniture, floors, art, and other expensive items in your home.  

NFRC’s energy-efficiency ratings for windows also apply to window films: the U-factor rating measures a film’s ability to block heat from escaping a home, and the Solar Heat Gain Coefficient rating measures its ability to block heat from entering one. The Visible Transmittance rating measures the amount of natural light that can pass through a film. To find certified window films, visit the NFRC’s Certified Products Directory. A window film expert can check your windows’ location, type, and condition to suggest an appropriate choice. 

Films can increase the surface temperature of the glass, and that may be a challenge for some window frames and glazing seals, which help to hold panes in place. Check whether films interfere with your window’s warranty and whether the do-it-yourself installation is recommended. Some window film manufacturers warranty their products if installed by a professional.  

Films are not the same as low-e (emissivity) coatings, which are applied to glass during the window manufacturing process, and may deliver greater efficiency and control. However, window films are a good solution to upgrade existing windows that are still in good condition. This can be a more environmentally friendly choice because it creates less waste than replacing the existing windows, which then need to be disposed of.