According to the US Department of Energy (DOE), between 25-35% of wasted building energy is blamed on inefficient windows. The California Energy Commission even estimates that 40% of a typical building’s cooling requirements are related to solar heat gain through windows.
“Window film not only works smarter when it comes to energy savings, it’s a greener choice as it offers a small carbon footprint,” says Darrell Smith, executive director of the International Window Film Association (IWFA). “Window film can be quickly installed on existing windows with minimal disruption to daily routine. It gives new life to once outdated windows so owners save on energy while improving the comfort of their work spaces. You can also avoid the removal and disposal costs of the existing windows.”
If it’s time to update your windows, consider these film options that will save energy, improve daylighting, and increase occupant comfort.
What is window film?
Window film is a flexible product composed of one or more layers of coated or chemically treated polyester that can be installed on glass. It is primarily used for retrofit applications to existing windows.
There are several types of window film products that are specifically designed for a particular end use. These include solar- and glare-control, insulating, ultraviolet (UV)-blocking, safety/security, privacy, and decorative.
The majority of window films offer up to 99% UV-protection, and solar-control films can be specified with different levels of insulation improvement. For exterior windows, solar-control and safety/security films are the most beneficial, whereas interior windows used for doors or glass partitions commonly use decorative products.
What are the benefits of window film?
Solar-control films can block as much as 80% of the solar heat coming through glass into a building, decreasing the heat load on the air conditioning system to create reduced energy costs. Professionally installed window film can also reduce cooling costs by up to 30%.
Films can be darker for glare control or privacy purposes or else appear almost totally clear. Over 250 solar-control films are certified by the National Fenestration Rating Council, so users can be assured of the energy performance potential.
Safety and security window film controls the behavior of broken glass fragments by holding the pieces together. This can greatly enhance the safety of building occupants and protect interiors from damage caused by flying glass pieces. These products can be used to bring unprotected glass up to certified safety standards for impact (by objects and from human impact) or enhance blast protection (such as from a chemical explosion in a laboratory).
Decorative films can be used to make standard glass look like frosted, etched, or patterned glass. They also comes in colors or white/black matte looks, enhancing both aesthetics and privacy. Although not designed specifically for this purpose, both standard solar-control and decorative films have the ability to minimize a portion of flying glass fragments should the glass break.
Can window film be installed on older windows or glass?
The newer the building, the greater the energy-control capability of the window system generally is, so there may be less energy savings potential for the use of window films on newer glass. Adding window film to older windows will results in higher returns.
However, normal glass stops little ultraviolet energy, so even the addition of clear UV-blocking window film offers benefits. In addition, some newer windows have extremely high visible-light transmission and may create areas of excess glare.
Even the newest windows, which advertise added UV protection as a benefit, usually provide no more than 70% UV block. A trained window film specialist using specific tools and guidelines from a manufacturer can determine how much added energy savings and other benefits might be achieved by adding window film to these newer types of windows.
How is window film installed?
Although window film can be installed as a do-it-yourself product, to get the best results and maximum manufacturer’s warranty coverage, a skilled professional window film company should install it.
Installation of the film can be done on a room-by-room basis or after regular facility hours (such as evenings or weekends), so literally overnight windows can be covered with little to no disruption to normal operations.
How long will window film last?
Window films will normally have at least a five-year manufacturer’s warranty, but products today generally have 10 to 20 years of warranty coverage from the manufacturer, dependent on the specific film and intended use.
The U.S. Department of Energy Weatherization software uses a 15-year life expectancy for low- to medium-price window films on windows in older buildings, so the expected life of the window film may exceed the warranty period.
To learn more about how to reduce energy costs with window film without changing architectural integrity, you can download this free information booklet: www.iwfa.com/ConsumerInfo/IWFAWindowFilmBooklet.aspx
Darrell Smith is the executive director for the International Window Film Association (IWFA).
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