That navy blue sofa in front of the window used to look great. Now it's two-toned. Without protection — from blinds, drapes, or glass coatings — ultraviolet rays coming through a window cause furniture, floors, and wall hangings to fade.

Window film was introduced in the 1960s to reduce both UV fading and window glare. More than 40 years later the product carries with it the stereotype of tinted plastic. But during the last few years manufacturers have introduced far more sophisticated products that are, says Lawrence Constantin, director of sales for window film manufacturer Solar Gard, capable of modifying most of what the sun does in a home. Today homeowners not interested in glare control can buy film that protects from UV rays and blocks solar heat gain but is also invisible. “Just because you have a sun problem, which gives you a heat problem, the last thing you want to do is destroy your view,” Constantin says.

AFTER MARKET OPTION Window film can allow homeowners to improve glass performance without changing out a window. It's not a solution for rotting frames or water or air leaks, but if the windows are structurally sound, film might be an option for those who can't afford to replace, says Darrell Smith, executive director of the International Window Film Association, in Virginia — or who simply want better glass performance. “We install it in a lot of homes that are relatively new,” says John Parker, owner of National Security & Window Filming, in Oak Forest, Ill. His company does both commercial and residential window film installations. Even some large home improvement companies, such as Statewide Remodeling, in Texas, now sell film as an aftermarket product.

PROFESSIONAL INSTALLATION Smith, suggests that although solar film can be installed by DIYers wishing to save themselves the $3-to-$11-per-square-foot professional installed cost, there are advantages to hiring a pro. Professional installers know to test the window for existing coatings, check the film-to-glass ratings that leading manufacturers include on their packaging (to avoid heat buildup on the glass), and understand both window-film warranties and the circumstances under which applying window film could void those warranties. They can also suggest the product that's most appropriate. “Sometimes [homeowners] have done their research,” Parker says, ”and sometimes they don't know what their needs are.”