Installing Window Film

My windows are in good shape, but I want to block the heat and glare and reduce furniture fading. Will installing clear insulating do-it-yourself window film help much and also save energy during the winter?—Meg H.

Applying window film yourself or having it professionally installed is an excellent solution to minimize overheating, glare, and fading. You will also be surprised at how pleasant it is to be in a room without harsh glare from windows. Instead of drawing the curtains or blinds and switching on a lamp, which uses electricity, you can often leave the curtains open and the lamp off. Using lamps during the summer also creates more heat your air conditioner has to run longer to remove.

With normal window care and cleaning, the new residential window films may last 10 to 15 years. When you consider the year-round energy savings and resultant lower utility bills, plus the longer life for furniture, curtains, and carpeting, applying insulating window film can easily pay back its cost.

Some manufacturers offer only do-it-yourself or professionally installed window films and others offer both. The primary difference between professional and do-it-yourself films is the type of invisible adhesive used to fix the film to the window. Professionally installed film usually has a fairly long warranty. You can purchase special adhesive dissolving solution to use if you later decide to remove the film.

Many of the newer residential window films, especially the do-it-yourself insulating film kits, are nearly clear. Typical color choices for the lightly tinted films are platinum, gray, and bronze. Even with just a slight tint, they can block more than 50 percent of the total solar energy that hits your windows.

The new insulating window films function in a similar way to efficient low-emissivity (low-e) replacement window glass. To create the low-e properties, a microscopically thin layer of metal is deposited on the film. This layer is so thin, visible light passes through it and it appears to be totally transparent. Window film is actually made of many layers and the metal film is deposited on the inner layers for protection.

If you apply this insulating film to all of your east-, west-, and south-facing windows, the reduction in your air-conditioning electric costs will be noticeable. Not only will the film block heat, but without the intense radiant heat and glare from windows, you can often be very comfortable with the thermostat set several degrees higher.

If you can wash a window, then you can easily install insulating window film yourself. You can purchase the film in pieces from a roll or already prepackaged and a simple installation kit. Most films have a water-activated adhesive on one side. Thoroughly wash the window and leave it wet. Wet the film, place it over the window, and squeegee it flat to the window. Cut off the excess around the edges and let it dry.

Although they look identical at the home center store, not all window film kits perform the same. Be sure to compare their properties—emissivity, shading coefficient, and visible light transmission.

Lower emissivity films are best for year-round comfort and savings. Lower shading coefficient films block more heat. Lower visible light transmission films block more glare, but can make the window darker. All window films make glass shatter-resistant for safety during storms or around your children.