You’re probably already very familiar with the phenomenon of solar heat gain, if not the nitty-gritty science behind it. Basically, it’s the reason we (begrudgingly) close the shades at home on hot, sunny days – and it’s the cause for some very steep cooling bills. For many buildings, window film solves the problem of being able to let sunlight in without overheating the work environment.
How do window films work?
A window film is a thin, tacky material that you coat the window with. The technology used for the window film is good, so you can’t see it unless you look really closely. The film only allows visible light to come through, but not heat and ultraviolet radiation from the sun. This keeps the inside of a building from heating up when the sun is shining on it.
Our 50 Hurt Plaza property in Atlanta was one of those overheating buildings. Built between 1913 and 1924, the Hurt Building is one of Atlanta’s first skyscrapers that incorporated modern amenities in its classic architecture. At the time it was the largest building in the south. This historical building is currently listed in the National Registry of Historic Places, won the 2014 Southern Region Historical Category TOBY Award, and is the oldest office building in Georgia to achieve a LEED-EB Platinum certification. The BEST program improvements to the property’s performance through efficiency, energy conservation, and improved systems directly contribute to the quality of the office building.
Of the Hurt Building’s 436,340 square feet spread over 18 floors, we determined that 62% of the available window area needed to be filmed – roughly 19,500 square feet! Not every window in a building need have high-tech film installed; only those that receive a large amount of direct sunlight.
On those windows, we installed HanitaTek Medium Silver 35 film. This is a reflective film designed for maximum efficiency at a competitive price, with a Solar Heat Gain Coefficient (SHGC) of 0.32. The lower the SHGC, or “G-value,” the more heat is rejected. In this case, the windows with film installed achieved a 67% solar energy rejection rate.
Let’s crunch the numbers. Project costs, including materials, labor and taxes, totaled $50,411. The resulting annual utility savings generated by a reduced solar load? $86,685! In other words, it only took seven months to “pay back” the project costs, and the building will continue reaping the savings on utilities for years to come. And lest we forget, the less it takes to cool the building, the more we reduce energy usage – and that’s always a good thing. See the complete Window Film Installation Business Case here.
Another simple solution … another mighty return on investment (172%). It’s what BEST is all about: making the changes that make sense, both financially and environmentally. The only question that remains is, what would YOU do with that kind of annual savings?
For more information about how the BEST program improves the efficiency of office buildings, visit our Lighting Retrofits case study or the Cost-Benefit Analysis tool.