Reflective film, which adheres to glass and is often seen on commercial buildings, can block up to 85 percent of incoming sunlight. In the summer, solar films can reduce heat gain, making homes more comfortable and cutting cooling costs. In addition, they reduce fading of carpets, furniture and fabrics by the sun's UV rays. Unlike closed drapes or blinds, reflective films work by stopping the sun's heat outside the window before it enters the home -- and you keep the view. In the winter, window films can reduce heat loss by reflecting heat back into the home rather than letting it escape through the window.
Because films block sunlight year 'round, it is inappropriate on south facing windows in passive solar homes. However, it may be practical on tough-to-shade east and west facing windows. Because the sun is low in the sky as it rises and sets, east and west facing windows are best shaded with materials like solar films or screens that cover their entire surface. Films are not recommended for windows receiving partial shading because the uneven heating of the glass may cause it to break or ruin the seals between double-glazed units.
Solar films come in a wide range of tints like bronze, gray and neutral tones that are virtually invisible from the inside. They are available with scratch-resistant coatings and can be cleaned with a mild soap and water solution.