An energy-efficient building envelope can eliminate wasted energy and take your sustainable initiatives to the next level. There are several solutions available to make the building envelope more efficient, from exterior louvers and solar screens to interior shades and blinds. One of the easiest, most inexpensive things you can do to immediately improve performance of the building envelope while still maintaining a view to the outdoors is to install window film.

Energy-Saving Expectations

The majority of energy transfer in or out of the building envelope occurs through the windows (approximately 40 percent), and about one-third of a building’s cooling costs can be attributed to solar heat gain through windows. You can imagine that any change made to improve window performance can make a significant difference in the energy wasted through the building envelope.

Solar heat gain is often a problem for high-rise facilities because shade is difficult to find above the street level and some high-rise units may have windows constantly exposed to harsh sunlight. So how much can window film improve insulating performance of your building’s windows? Most energy-efficient window film can help reduce solar heat gain by up to 75 percent, which translates to average energy cost reductions of between 5 and 15 percent. An upgrade to the newest low-e window film technology can improve insulating performance by as much as 92 percent. In most cases, facilities managers see ROI on window film within three years of installation.

Operating its HVAC system at full capacity, this Marriott hotel in Winston-Salem could only cool the sunniest rooms down to 78°F. Their solution was to install window film on over 800 windows. The same mechanical systems can now
achieve an interior cooling temperature of 72°F.

Because of its contribution to energy efficiency, window film is being recognized more and more as a smart solution. In fact, window film was recently incorporated into California’s state building code, making California the first state to recognize window film as a practical way to save energy by reducing solar heat gain and improving window performance.

Window film was also recently found to be the most cost-effective choice for energy savings in retrofit applications. An independent study from ConSol compared window film to other traditional energy-saving techniques like updating HVAC systems, air sealing and caulking, and adding R-38 ceiling insulation. Window film came out on top as the most economical way to save energy and reduce a building’s carbon footprint.

By making windows more efficient, air-conditioner runtime and load conditions can also be reduced, which affects the energy bill and the bottom line. For example, if a building has several large glass areas facing north and south, additional cooling may be needed to maintain comfortable temperature levels for occupants in spaces with southern exposure. But because the HVAC system is trying to cool the areas with southern exposure, the workspaces with northern exposure may be overcooled as a result. By reducing solar heat gain in the south-facing areas with window film, the HVAC system is better able to maintain comfortable temperatures across the facility.

An Added Benefit: UV Protection

Not only is it energy-efficient, but window film can also provide a barrier between harmful UV radiation and a facility’s occupants, finishes, and furnishings. UV protection is an important part of a high-performance building envelope.

There are three types of UV rays given off by the sun: UVA, UVB, and UVC rays. UVC rays are absorbed by the ozone layer, so they’re not of any consequence when discussing window performance.

Coming in from the exterior through a building’s windows, UVA rays cause a multitude of problems inside, including fading furniture, flooring, artwork, wallcoverings, and merchandise. These rays are also responsible for initiating skin cancer development and causing signs of aging due to the damage they cause to skin cells.

Unlike UVA rays, UVB rays change throughout the year. They’re more prevalent in summer, and are more powerful when they reflect off water or snow.

Ordinary window glass in a commercial building offers minimal to modest protection from UVA and UVB rays. But the right window film can block up to 99.9 percent of harmful UV rays, defending against the dangers of skin diseases and fading.

Other options are available that can offer UV protection, such as curtains, blinds, or awnings, but these solutions can create a dark interior environment or block occupant views to the outdoors. Replacement windows with special UV protection coatings are also available, but window film tends to be 80 to 90 percent less expensive to install than replacement windows. The installation process is much quicker, less disturbing to occupants, and easier on the landfill because there is no need to dispose of old frames and window glass.

For facilities managers who are ready to tackle energy efficiency of the building envelope, window film is a good way to immediately see improvement in window performance and receive the added benefit of essential UV protection.

Steve DeBusk

Steve DeBusk is global energy solutions manager for Solutia Performance Film’s Vista brand.