Energy efficient window film

Turn your windows into energy efficient windows in no time flat

Energy efficient window film gives you a quick way to turn old, inefficient windows into highly efficient ones. This window film works by blocking infrared radiation from passing through your window glass. This means that in winter, heat from your rooms doesn’t radiate out to the cold outdoors, saving you on your heating bills, and in summer, heat from the sun doesn’t get in.

I recommend energy saving window film in situations where you have older, or low-efficiency, but still airtight windows, and tiy want to increase their energy efficiency without spending a lot of money on new windows. These films not only cut on radiant heat passing through your windows, they also reduce UV radiation entering the home, and the amount of visible spectrum light as well.

Note: If you’re looking for the window plastic you apply to the inside window frame and then shrink with a blow dryer, see my page on plastic window insulation instead.

Energy efficient window film is easy and fast to install, so you save money on the installation as well. Clean your window glass well; cut sheets of energy efficient window film to the correct size for the glass. Add a few drops of dish detergent to a spray bottle filled with cold water, and mist the window glass lightly. Then apply the window film, smooth it with a squeegee (often provided as part of the window film kit), and you have a much more efficient window than you did five minutes earlier!

Of course, this energy efficient window film doesn’t block out all infrared radiation, but it does get most of it. And it provides close to the same level of energy efficiency as buying new windows with low-E coatings, assuming your existing windows aren’t leaky.

The film at right is available in a 6’6″ roll 17.5″ wide, so suitable for narrow to average size windows but not for wide ones (unless the window panes are less than 17.5″ high in which case you just rotate the material 90 degrees).

If your window is larger than 17.5″ in both dimensions, you can apply several pieces to the same window. As the film is almost impossible to notice once installed, the lines between sheets barely show. Alternately you can look for other energy efficient window films (e.g. search for UV window film) with more appropriate dimensions.

This film can block 99% of UV rays and 85% of infrared radiation, reducing the heat loss that normally escapes through your windows in winter, and the solar energy that normally enters through the windows in summer. We have a south-facing sliding glass door in our breakfast nook and as a result the breakfast nook used to get extremely hot on summer afternoons; as a stop gap I would hang a tarp outside to keep the sunlight out. We bought three sheets of the 48×48 film and applied it to the inside of each door (the glass panes were slightly higher than six feet so we had a tiny gap at the bottom), and the results were fantastic – we still had natural light, but the breakfast nook was suddenly comfortable again. And the film is still holding up two years later. The seams are barely noticeable.

Most window films are available in tinted, privacy, and glazed forms as well. Tinted films are typically a shade of grey; privacy films have a mirror-like appearance from outside, but you can see the outside clearly from within; and glazed forms are cloudy so you can get the light from outside but you can’t see clearly (often used for bathroom windows). It’s important when shoping for energy efficient window film to ensure you’re getting film with the right energy saving characteristics. If you want to minimize heat gain look for film that indicates its infrared blocking capacity.

When installing any window film, it’s a good idea to buy a little more than you need, and start with a practice run on a small piece of glass or a small window pane. Although we had no trouble installing ours, many reviewers report problems especially their first time through. Problems include getting the air bubbles out, getting the film to adhere to the glass, and getting the edges trimmed neatly. Find a small basement window or even an old storm window pane to practice on. Wasting a one-square-foot piece up front to learn the technique is much better than wasting a 3×4 foot piece on your first big window.

If you have a large number of windows to cover, you can buy the Gila heat control window film, which comes in rolls 36″ by 15′ long. This used to be a more expensive product but on a square foot basis was far cheaper, and is now priced competitively with the 48×48 Artscape kit. You have to purchase a separate kit for it that includes the squeegee and their own proprietary solution for getting the energy saving window film to stick, but judging from the customer reviews this kit really makes the job much easier. And because the film is 36″ wide, which is wider than almost any window, you can typically avoid the minor visual annoyance of seams when you install on larger windows.

You may have come to this page looking for plastic shrink wrap window insulation kits. These kits are more suitable for windows where there is a major draft. Energy saving window film saves energy by preventing radiative heat transfer (infrared radiation going through glass), while window insulation kits prevent convective heat transfer (hot air passing through air gaps in cracked glass, cracked window putty, or poorly sealed windows or window frames).

For information on window insulation kits see my Energy saving window coverings page.