Low-e Applied Film Window Retrofit for Insulation and Solar Control

Nationwide, on an annual basis, windows in commercial buildings are responsible for 0.96 quadrillion BTUs (quads) of heating energy and 0.52 quads of cooling energy (Apte 2006). This is equal to about 1.5% of the total energy consumption by the United States in 2011, and is equivalent to the energy consumed by more than 8 million U.S. households (US EIA 2012). There is substantial potential for reducing both the heating and cooling energy use in existing commercial buildings associated with windows by using a wide range of technologies and strategies. This study focuses on a new solar control window film retrofit technology that also provides improved thermal insulation, enabling both heating and cooling energy savings. A previous study estimated that there is a potential to save 0.65 quads of heating and cooling energy if the entire U.S. commercial building stock were to be retrofitted with typical solar control, low-emissivity (low-e) double pane glass units (Apte 2006). This represents a 44% savings of window-related heating, ventilation and airconditioning (HVAC) energy compared to the windows of the existing U.S. building stock, and 15% savings of all the building HVAC energy. Particular buildings may experience higher or lower energy savings depending on window configuration and climate.