Driving up next to a limousine can make you wonder who is inside -- a celebrity, an athlete or a newlywed couple. While the passengers are probably more interested in privacy, the dark-tinted windows also offer them protection from the glare and sun. Much like cars, window films are now being used in residential settings to offer homeowners the benefits of a sun filter to block some sunlight, while allowing other light into the home.
Sunlight can be helpful when it's aiding in plant growth or warming the Earth. Yet these same characteristics of heat and light can also make it a nuisance. In particular, infrared, ultraviolet and visible light rays are the primary concerns when it comes to sunlight affecting people's lives. These types of solar radiation are all part of the spectrum of light that makes it through the Earth's protective atmosphere. Infrared and ultraviolet light rays are invisible to the human eye [source: The Kingfish Science Encyclopedia]. Infrared light carries heat energy, while ultraviolet light is the radiation associated with sunburns. Visible light is made up of the many wavelengths of light that allow us to see different colors.
For centuries, people have been devising ways to shield themselves and their possessions from the sun. Starting with bonnets and sun umbrellas, then moving to sunglasses and sun-protective clothing, people have been inventing new ways to deal with the ever-present solar radiation.
In the 1960s, a new technology called window film came on the market. Since that time, the technology has continued to evolve, offering homeowners another option for protecting their family and property. These advances in technology now allow for window films that can block a significant amount of heat energy while still allowing the homeowner to enjoy a virtually unimpaired view from the window.
In this article, we'll look at what a window tint is and how to evaluate various window tints, costs and maintenance.
Types of Window Tints
Basically, a window tint, or solar control film, is a very thin film usually made of a polyester base with a scratch-resistant coating. Some films involve multiple polyester layers to achieve their results. These films are still only millimeters thick and are affixed to the interior side of the window with an adhesive.
In order to create the sun barrier, manufacturers use different additives in special, usually patented formulations to create the desired characteristics. One type of film is dyed. This method for keeping the sunlight from affecting the interior environment of the home utilizes absorption of the sun's harmful rays. It should be noted that absorption of heat can increase the stress on the window's glass, which can periodically lead to glass breakage. According to the International Window Film Association's Web site, use of any window film will increase the thermal stress on sunlit glass [source: International Window Film Association]. For this reason, it's important to check the manufacturer's window restrictions before deciding on the appropriate film.
Two other types of window film work by reflecting a majority of the sun's harmful rays. One film is metalized, which means that the polyester base is embedded with different types of metals. The newest variety of film uses advanced ceramics to reflect sunlight.
Along with different methods for dealing with the sun, window films also come in many shades and colors. These can range from opaque to clear. Many of the tints available have a slight metallic look, such as bronze, stainless steel or gray. Some newer versions of window films are nearly clear. Along with style, color or shade can also offer other benefits. Tinted versions tend to offer more privacy, while the clearer films tend to be less reflective, giving less of a mirrored appearance in the evening.
Why Tint Your Windows
Window tints can be evaluated on a number of different criteria depending on the goals of the homeowner. One window film might offer more heat reduction, while another window film might provide more privacy. Window tints have many beneficial qualities, but there can be a trade-off. Knowing how to evaluate these qualities can help you make your final decision.
Energy savings can be one of the most important criteria in choosing a window film. In new homes, windows can cause about 75 percent of heat gain during the summer months, which drives up air-conditioning costs [source: Morrill and Wilson]. This heat gain can also affect your overall budget. According to the U.S. Department of Energy, 45 percent of a typical utility bill is dedicated to heating and cooling [source: U.S Department of Energy].
The amount of energy savings is dependent on a number of factors, including tree shading and the orientation and location of the house, along with the type of film used. When evaluating the ability of a film to reject heat, first you must look at what's causing the heat. Most of the heat from the sun comes in the form of infrared rays, so preventing those rays from entering the home will help to reduce heat inside the home.
When evaluating heat reduction, there are two important factors to look at in a window film: the solar heat gain coefficient and solar reflectance. The solar heat gain coefficient involves the amount of solar energy that the film is letting into the building. The lower the solar heat gain coefficient, the less heat transmitted into the building. Another important measure is that of solar reflectance, or the amount of sunlight reflected by the film. Films with high reflectance ratings will provide greater heat reduction [source: Solar Gard Window Films].
Benefits of Tinting Your Windows
Along with heat reduction, window film can also help you protect your investments. Curtains, furniture and even flooring can fall victim to the effects of the sun. One of the leading culprits in fading your valuables is ultraviolet light. To keep those home furnishings and decorations looking their best, a window film with a high percentage of ultraviolet light rejection would be a good choice. Many films can now block almost 99 percent of the sun's ultraviolet rays.
Ultraviolet light can not only fade your furniture, but too much of it can affect your health. Ultraviolet rays are the reason for sunburns and are also seen as one of the risk factors for cancer. According to the Report on Carcinogens released by the Department of Health and Human Services, ultraviolet radiation is a known human carcinogen [source: National Institutes of Health]. For working to prevent sun-induced skin damage, several types of window film have even been given the Skin Cancer Foundation's Seal of Recommendation [source: The Skin Cancer Foundation].
Some window films offer another benefit in the area of safety: shatter resistance. The film's shatter resistance comes from its ability to hold glass shards together and act as a barrier between the interior of the home and the glass.
Along with the safety benefits, window films can also help to reduce the glare on your television when viewing the big game. The percentage of glare reduction is usually related to the visible light transmittance. The lower the amount of light transmitted through the film, the greater the glare reduction inside the home.
While a darker film can offer more glare reduction and privacy, a clearer film offers a more natural view from the window. Darker films can also have higher values for reflectivity. Reflectivity can be beneficial when reflecting the sunlight, but it can be less desirable when the view out of your windows at night includes a shadowed version of the room's interior.
Applying Window Tint
While the type of film you choose will affect the price you pay, the application technique will also greatly influence the final total. The two basic application choices are do-it-yourself or professional installation. The application procedure will differ depending on the type of window the film is being applied to, along with the type of window film.
The basic application procedure begins with a thorough cleaning of the window. After cleaning, measure the window, then cut the film to include an additional 3/4 to 1 inch (1.9 to 2.54 centimeters) of extra material on all sides. Exposing the adhesive coating is the next step in the process. For do-it-yourself application, it might be a good idea to have a friend help to separate the protective liner from the adhesive to ensure that the film does not attach to itself [source: Hawks].
Since most of the adhesives used on window films are water activated, the film and window are sprayed with a wetting solution. The films are then ready to be applied to the window with the adhesive side towards the window. To smooth out any bubbles or imperfections, it's generally recommended to use a squeegee and possibly more wetting solution to get a consistent look. When the film is smooth, the excess film can be trimmed. The surface should then be blotted to remove any extra water.
Window films usually need to cure, or dry out, for a period of time. This process can last anywhere from a couple of days to more than a month.
Obviously, do-it-yourself installation is going to be less expensive than professionally installed window tints. Costs can range from around $1 per square foot for a do-it-yourself film to $35 per square foot and up for highly specialized professionally installed films. It's also important to note that several brands of window films are exclusively sold through professional installers.
Maintaining Tinted Windows
After installing window films, maintaining them is the next priority. Window films can be cleaned only after they've been fully cured. Most window cleaning solutions can also be used on window films. Alternative cleaning solutions also include vinegar and water or soap and water solutions. Most manufacturers and installers do recommend avoiding abrasives, from chemicals to rough paper towels.
Even with perfect maintenance, window films can need to be replaced over time. The average lifespan of window film ranges from about 10 to 15 years. Most film manufacturers offer at least a five-year warranty, while other films come with lifetime warranties.
Some film manufacturers will extend the warranty to the glass in the window, as well. This extension is usually made because making a change to the glass, such as adding window film, can void the window manufacturer's warranty. It's important to know all of the warranty information on both your windows and the window film before installation.
While window film is removable, some films come off more easily than others. Many professionally installed films have to be scraped off of the windows. While do-it-yourself films are easier to remove, they still can't be reused because of the adhesive bond [source: Birkenmeier].
For more information on tinting the windows in your home, other energy-efficient tricks and related topics, see the helpful links on the following page. You may be able to save your furniture and some money at the same time.
Related HowStuffWorks Articles
More Great Links
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