Anyone who has worked beside a sun-exposed office window knows how uncomfortable solar heat gain can become.
The problem can occur even during cooler weather. Direct sunlight passing through glass can create localized hot areas while the building’s HVAC system continues trying to maintain comfortable temperatures across the rest of the space.
Heat-reducing window film, more commonly called solar control window film, is designed to address that problem.
Reducing Solar Heat Without Closing Off the View
Blinds and shades can help control sunlight, but they can also block natural light and exterior views when closed.
Solar control film works differently.
Depending on the film selected, it can reduce solar heat and glare while still allowing useful daylight through the glazing.
The U.S. Department of Energy notes that unwanted solar heat gain through windows affects building cooling loads and that improved window technologies can provide opportunities for greater energy efficiency and occupant comfort.
Learn more about window performance from the U.S. Department of Energy
Solar films may also reduce ultraviolet exposure that contributes to fading of furnishings, finishes, artwork and other interior materials.
Interior and Exterior Solar Films
Many commercial solar-control installations use interior-applied film, but exterior products are also available.
Exterior film can be useful on some glazing systems or architectural conditions where an interior installation is impractical.
Film selection must account for:
- glass type and construction
- coatings already present on the glass
- window orientation
- solar exposure
- desired visible-light transmission
- interior versus exterior installation
- manufacturer compatibility requirements
For this reason, it is better to select film according to the actual glazing system than to assume that one clear or reflective product works on every window.
Comfort and Energy Performance
Reducing solar heat gain can improve conditions for occupants sitting near exposed windows and may reduce cooling demand.
But claims such as “the film will pay for itself” should be evaluated building by building.
Energy savings depend on factors including climate, orientation, glazing area, film performance and HVAC operation.
For larger commercial buildings, an energy analysis can help estimate the potential benefit before installation.
CWS has completed solar-control work on demanding commercial properties such as the Walter E. Washington Convention Center, where approximately 42,000 square feet of solar film was used to address heat, glare and fading issues.
For commercial buildings with significant sun-exposed glazing, solar control film provides a retrofit option worth evaluating before major glazing replacement.
