QUESTION: I cannot afford new windows, but I thought about installing permanent winter/summer film on my old windows. Does it save energy, will it darken my windows and can I install it myself?ANSWER: People generally think of window film as the darkly tinted or highly reflective film used on skyscrapers or commercial showroom windows. These types of window film also can be used on homes, but there are now more energy-efficient, year-round residential window films which are only slightly tinted and reflective.The newer insulating residential window films use a technology similar to energy-efficient replacement windows. A low-emissivity heat barrier coating is deposited on the window film. This coating is usually a microscopically thin layer of metal atoms which is reflective to heat energy, but allows most of the visible light wavelengths to pass through.Using this technology allows a relatively clear window film to block the sun's heat during summer without the dark or reflective appearance.During the winter, the low-emissivity properties of the coating help block indoor heat from being lost outdoors through windows. You might also feel more comfortably warm sitting by a film-covered window during winter.Another advantage of residential window film is it blocks most of the sun's ultraviolet rays which are responsible for much of carpet, drape and furniture fading. All window films do this because of the base plastic film properties, but the low-emissivity coating is even more effective.If you already have double-pane window glass, dark films, which absorb heat instead of reflecting it away, could cause the window glass to get quite warm. This can cause a failure in the airtight seal between the glass panes. If this happens, a fog can form between the panes.The nearly clear low-emissivity energy efficient films do not cause the glass to get as hot because they block more of the sun's heat instead of absorbing it. First, check with your window manufacturer about its warranty. Some void the glass warranty no matter what type of film you apply.When shopping for do-it-yourself window film at your home center store, the low-emissivity residential often looks darker on the roll than when it is actually installed on the window. Do-it-yourself films also are available in boxed kits with a squeegee and other simple application tools. If you want a long warranty on the film, have it professionally installed.It is easy to install window film yourself on average-size windows. It usually has a moisture activation adhesive. Once it is wet, a squeegee is used to force out any bubbles so it adheres to the glass. An important key for a good-looking job is to make sure the glass surface is thoroughly clean.The following companies offer energy-saving window films: Bekaert, 877-273-4364, www.solargard.com; CPFilms, 800-528-4481, www.cpfilms.com; Solamatrix, 800-777-1770, www.solamatrix.com; Madico, 800-225-1926, www.madico.com; and Plastic View International, 800-468-6301, www.pvifilm.com.

Send inquiries to James Dulley, Butler Eagle, 6906 Royalgreen Dr., Cincinnati, OH 45244 or visit www.dulley.com.