Want to lower the summer temperature of your home and your utility bills at the same time? Try reflective window film. That's right, window film!

In most homes, windows are responsible for the greatest amount of heat gain in the summer and heat loss in the winter. One way to improve this condition is to replace the windows with insulated glass or double-pained windows. For many, this course of action is far too costly.

Independent consumer tests have shown that reflective window film can deflect up to 79 percent of the sun's heat and glare in hot weather and keep up to 19 percent of inside heat from escaping in cold weather. And many reflective films also eliminate 96 percent or more of the sun's ultraviolet rays, a major cause of fading of furniture, flooring, and window coverings.

Reflective window film consists of a thin layer (approximately 1-2 mils) of polyester sheeting. It comes with a high-pressure acrylic adhesive designed for a long-lasting bond. Most films contain either aluminum or copper particles to give them high reflective quality. They come in a variety of thicknesses, colors and shades. These variations influence the amount of visible light and ultraviolet rays transmitted and the percent of solar energy rejected.

Unlike in its fledgling years, the window film industry now can offer a product with high reflective qualities that resists scratching, fading, and lasts longer.

Installation is one of the keys to a successful result. Applying this stuff makes wallpaper hanging look easy. Better warranties are generally offered when the product is professionally installed. This sometimes makes the cost of professional installation worthwhile.

For those who are seasoned paper-hangers, however, looking for a new challenge, we offer the following do-it-yourself installation tips.

Since the film will be applied to the interior of the window, start by cleaning the glass thoroughly. Use a single-edged razor blade to remove any paint or other particles from the surface. Once the glass is clean cut a piece of window film, usually purchased in rolls, about 2" larger overall than the size of the window.

Next, mix one teaspoon of liquid dish detergent with one quart of water in a spray bottle. Soak the inside surface of the window with the soapy solution. Peel back the liner paper to expose the adhesive. A helper will make this step substantially easier.

Drench the adhesive side of the film by spraying it with the soapy solution. It's a good idea to have a drop cloth and towel handy to keep a mess minimal. Place the adhesive side of the drenched window film against the wet window, and using your hands begin to smooth the film against the surface of the glass, eliminating any wrinkles.

Spray the surface of the film facing you with the soapy solution, and using a rubber squeegee continue to smooth it against the glass, working first horizontally from the center to the side and then vertically moving the solution to the bottom of the window.

Finally, using a straight edge and razor knife trim the film where it meets the window frame. To avoid a gap at the window frame, force the film into the joint and into the corners with the straight edge before trimming.