Do you sometimes feel like you need to wear sunglasses inside your house? Do you love the natural light all your windows bring in but hate the high summer cooling bills? If so, look into window films. While they may bring to mind images of limousines or mirrored skyscrapers, residential window films actually come in a wide range of styles and finishes and are a nifty way to keep the sun’s rays from fading fabrics and overworking your air conditioner.

What Are Window Films, Anyway?

Sunlit Living Room

Window films are manufactured by applying either dye or vaporized metals to sheets of very thin polyester. The metal acts like a mirror and keeps sunlight and its accompanying heat from entering a room by reflecting it off the film. Dyed window films will darken a window to lessen glare and help guard fabrics against fading. To achieve an assortment of looks and purposes, window films can be made with different metals in varying levels of concentration, or they can be dyed different colors.

A window film’s ability to block heat and allow light into a room is referred to as the Light-to-Solar-Gain (LSG) ratio. The higher this value, the better the film will be at transmitting natural light while reducing solar heat gain. Also, window films with a lower LSG value will result in a darker window than those with a higher LSG value.

Because of limits in manufacturing processes, a high LSG value is difficult to find in aftermarket window films that must be manually applied. Window film products that are integrated into the glass itself during the window manufacturing process usually hold a higher LSG number. Generally speaking, a window film will lend a slightly darkened appearance to plain glass from both the interior and exterior of a room. If all the windows have a film applied to them, that change in appearance will likely not be very noticeable—depending, of course, on the level of tint.

Tinted Window Films

Modern House with Window Films

It’s important to note that dyed window films will only absorb—not reflect— the light and heat from the sun, so they may not be the best choice if temperature control is a concern. Since there is no metal present in a dyed window film, there is no mirrored effect. In fact, the dark tint of the window film will absorb solar energy and dissipate it through the window and into the room. Depending on where in the country you live, this may not be a problem. If, however, you live in a moderate climate and your goal is simply to reduce glare in a room or help furnishings and textiles last longer by protecting them from fading, tinted window films are an excellent choice.

Solar Control Films

Compared to an untreated window, solar control films can block approximately 80 percent of the sun’s energy. Solar control films are always constructed with metals or other particles that provide a reflective barrier to UV radiation, heat, and light. If you live in a particularly warm climate, solar control window films can help keep utility bills in check by blocking a significant portion of the sun’s heat before it enters your home. You will also reap the benefits of any other type of window film—furniture, carpet, and other textiles will last longer and be less likely to fade over time.

Window films are an excellent item to add to your home improvement project inventory, but don’t include them on your list of DIY tasks. In theory, some window films can be applied by the homeowner, but tackling that project by yourself is not recommended—unless you’re OK with a less-than-perfect outcome. For the best results, let the professional installers take on this job.  

View Local Window Tinting Companies

Sources: Ask the Builder; How Stuff Works; Johnson Window Films; The Florida Solar Energy Center at the University of Central Florida.