To prevent overheating and other problems associated with the sun – glare, fading, etc. – controlling sunlight in commercial facilities is crucial. As energy efficiency and occupant wellness become the focus of our buildings, daylighting is front and center in helping to create sustainable, healthy design.
Solar heat gain through windows can account for up to one-third of a building’s total cooling costs, according to the U.S. Department of Energy. High-performance, low-e window film and exterior shade systems are two options that can control the sun’s rays for improved comfort, lower utility bills, and reduced energy usage.
Exterior Shade Systems
Exterior shade systems can consist of overhangs, vertical fins, exterior louvers and blinds, or automated systems that integrate with building controls to retract or tilt based on outdoor conditions. The idea behind exterior shading systems is to stop direct sunlight from entering through a building’s windows.
These systems offer a number of advantages similar to those of window film. Exterior shading systems may result in energy savings by reducing direct solar heat gain through windows. They can also reduce glare without lowering window shades or closing blinds, maintaining access to daylight and outdoor views.
Depending on which style you consider, integrating an exterior shading system into an existing building may be a difficult process. If fixed overhangs or fins are used, they may not solve solar heat gain problems entirely. For example, a fixed overhang may be effective at shading a south-facing window during summer months, but won’t block low afternoon sun from entering a west-facing window.
Exterior shade systems also impact the building’s exterior aesthetic. The earlier that shading devices can be considered in a building’s design, the better off the building will be in terms of overall aesthetics. The shading system may also require regular maintenance and repair.
During winter months, exterior shading systems can increase heating loads because they redirect the sun’s rays year-round – including during these cold months when sunlight may be desired for its warmth.
Low-E Window Film
High-performance window film can improve energy efficiency and reduce glare, as well as prevent fading. Because window film is applied directly to the window, it reduces the amount of UV rays and solar heat gain that pass through. Low-e window film also allows for year-round energy savings by reducing solar heat gain in the summer and reducing thermal heat loss in the winter – unlike an exterior shade system.
Similar to overhangs or fins, window film usually doesn’t block views to the outdoors. But because it’s applied to the inside of windows, it won’t collect outside dirt or debris and doesn’t require as much regular maintenance and cleaning as exterior shading elements might.
Window film is also a great option for existing buildings and windows. In many cases, window film can improve the insulating capacity of existing commercial windows by up to 92%. Low-e films can offer single-pane windows the same insulating performance as double-pane windows, and provide double-pane windows with the same insulating performance as triple-pane windows. And it can be done without significantly altering the exterior building aesthetic.