Window films are hardly a new building product. They’ve been around for some forty years now, ever since the confluence of two separate events brought about the emergence of a commercial window film market, according to Nick Routh, government sales consultant for Bekaert Specialty Film in Clearwater, Fla. — the space race of the 1960s and the energy crisis of the early 1970s.
The space program was responsible for developing reflective surfaces to protect early spacecraft from excess radiant heat. The gold metallic foil that covered parts of the lunar lander became the conceptual basis for the first window films designed to reduce solar gain. But the early window films were not particularly well-received until the beginning of the next decade, during the country’s first sustained energy crisis.
“There were offices built in the 1950s that were basically glass towers,” says Routh. “There was a lot of solar gain in these offices and, because energy was cheap at the time, the cost to cool the buildings didn’t matter. But when energy prices went through the roof people began looking for ways to reduce the heat gain coming through the glass — especially for buildings heated and cooled using electricity.”
To reduce the sun’s warming effect, many buildings began to use window film for the first time. As a result, these walls of glass became huge metallic mirrors — an aesthetic not popular with everyone. Today, architects and building managers have a wide variety of window films to reduce solar gain. They range from clear to smoky amber, blue, and green tints to highly reflective metal alloy films.
In addition, window films also come in varieties designed to provide security and shatter mitigation — durable films that prevent against unauthorized entry and protect building occupants from flying glass, in an explosion. Window film has even evolved to include designs that simulate etched or frosted glass or incorporate graphic elements such as company logos.
The largest segment of the commercial building window film market is focused on energy control. This is despite advancements in window glazing technologies that have created tinted and energy efficient windows.“Window film is something that protects [designers] from the screw-up factor,” explains Virginia Kubler of CPFilms Inc., a window film manufacturer based in Martinsville, Va.
“An architect may have spec’ed-in windows that are fairly expensive but then get downgraded during construction,” she argues, for example “when the building is completed the cooling systems couldn’t handle the heat in the lobby. In cases like this, film does a very fine job of fixing the problem.”
But newly constructed buildings are not the sole domain of energy control films. By far the largest portion of this business is retrofitting older buildings — providing better comfort and lighting for tenants and helping to manage energy costs and smooth out energy demand. Darrell Smith, executive director of the International Window Film Association (IWFA), says the country can be split into three zones regarding energy control.
“The southern zone is the predominant market for window film, where cooling [occurs] during most of the year,” Smith says. The middle zone below Washington, D.C. and northern California requires films that reflect less light, and the northern tier relies upon the sun to heat the building during the colder months. Today, window film manufacturers have access to computer models that can help owners and architects calculate the most efficient level of solar rejection in terms of heating and cooling costs.
“I have a basic one on my laptop that I take around to give people demonstrations and to show the kinds of energy savings window film provides,” says Smith. “The manufacturers also have these and can customize the information for any building.”
Routh points out that it may only be necessary to apply film to the windows on one or two sides of a building to achieve significant savings. “In some cases, even a little reduction in the overall amount of energy used to cool the building will prevent it from paying the high energy costs associated with peak usage.” He adds that a computer simulation can make that determination, including payback time for the investment cost (about $3 to $8 per square foot).
In some areas of the country local utilities offer incentives designed to increase the use of window film. Current programs in California provide a rebate of between 35 and 50 percent of the cost of energy-control film installations. “The rebates are so high because Southern California Edison found that they get the highest return of energy saved per dollar invested with window film,” says Smith.
Besides energy savings, control of ultraviolet rays are an important consideration, especially in the northern tier where UV radiation is strongest. “In a commercial building or a hotel, furnishings are important and fading can be tremendous,” says CPFilms’ Kubler. “UV protection can prolong the life of furnishings and carpeting.”
Blast Hazard Reduction
While energy control represents the largest market for window film, safety and security films are the fastest growing segment of the industry. “Our business has increased between two and three hundred percent in the past few years,” says Scott Haddock, president of Glasslock Inc. of San Jose, Calif.,which installs fragment-retention window film (FRF) and is a pioneer in large-scale blast testing of retrofit safety film-to-glass products.
The real impetus for the protection of federal buildings began with the 1995 bombing of the Murrah building in Oklahoma City. Since 9/11, blast hazard reduction has caught the attention of the private sector as well. “What we have seen is companies realize that even if their building is near a potential target, the waves from a blast could affect their building,” says Tom Niziolek, sales and marketing director for window film manufacturer Madico Inc.
The interest of private industry is twofold: to protect the occupants of the building in the event of an explosion and to keep the building in service after a blast. Window film accomplishes this by essentially bonding the shattered glass together and keeping it in the window pocket. Window restraint systems are also available to keep the entire window from flying as a unit into the workspace, should the blast be strong enough.
Shatter-protection film is thicker than its energy-control films by a significant margin. Energy films are less than 2 mils (one-thousandth of an inch) thick, while safety and security films start around 4 mils and can be as thick as 12 mils. Film selection depends on performance testing based on U.S. General Service Administration (GSA) standards. “Madico has spent well over a million dollars testing our film to see how it measures up against GSA standards,” notes Niziolek.
Safety film is more expensive than energy-control film. Routh says a good rule of thumb is to estimate roughly $1 per square foot, per mil of thickness. Thus, a 6-mil-thick safety film will cost in the neighborhood of $6 per square foot.
In addition to safety, some window films are designed primarily to provide security, such as against forced entry to ground-floor retail shops or lobbies of buildings. These films are designed to keep intruders out of the space and prevent, for example, “smash and grab” robberies. Security films are up to about 12-mils-thick and with good reason. Unlike safety film, designed to prevent flying glass from a single impact, security films need to potentially stop multiple impacts — someone pounding the glass with a baseball bat, for instance — and not fail.
Another segment of the window film business is devoted to decorative and advertising films. With aesthetics in mind, decorative window films can do everything from simulate the look of etched glass to decorate retail locations with company logos. “It used to be that there was just frosted film and two or three colors,” says Kubler. “Now the patterns are more varied and people realize you can have a design on the glass with designs and patterns or colors.”
One application for the decorative films is inside a conference room or individual office that has windows overlooking a public space. Another application is the strategic use of decorative film to dress up vacant office space for attracting new tenants to the building, adds Kubler.
Companies can use colored film to create logos that can be applied directly to office or storefront windows. “Kinko’s and AT&T have used colored films for their logos and have them applied for a consistent feel to their locations and to keep their brand name out there,” says Routh. “Or they could be used in strip malls where there may be restrictions on the use of outdoor signs.”
Some films can even be applied to the exterior of a building as an anti-graffiti measure. This type of film protects the building from being vandalized by allowing the area of film marked up with paints or other markers to be peeled off.
CHRIS ANDERSON (CANDERS1@MAINE.RR.COM) IS A FREELANCE WRITER AND EDITOR BASED IN PORTLAND, MAINE, WHO WRITES ABOUT THE CONSTRUCTION INDUSTRY. FOR MORE INFORMATION, CONSULT THE INTERNATIONAL WINDOW FILM ASSOCIATION AT WWW.IWFA.COM