Low-e Window Film

GPG-032, February 2017

Low-e film blocks direct solar heat to reduce summer cooling demand, and insulates to reduce summer and winter energy use and improve occupant comfort. Researchers from Lawrence Berkeley National Laboratory found 29% average perimeter HVAC savings compared to single-pane clear glass. Click on the infographic below to enlarge.

GPG Findings 032, February 2017, ELECTROCHROMIC WINDOWS FOR LAND PORTS OF ENTRY. Opportunity: Windows areresponsible forhow muchenergy use? 34% OF COMMERCIAL BUILDING HVACENERGY IS LOST TO WINDOWS. Technology: How does Low-efilm work? REDUCES SOLARHEAT GAIN ANDINSULATESBY SELECTIVELY ABSORBING ANDREFLECTING HEATBlocks direct solar heat to reduce summer coolingdemand. Improves window insulation to reducesummer and winter energy use and improveoccupant comfort. Measurement and Verification. Where did M and V occur? LAWRENCE BERKELEY NATIONAL LABORATORY assessed a low-e filmprovided by the Eastman Chemical Company at two sites, the Hansen FederalBuilding in Ogden, Utah, and the Cabell Federal Building in Dallas, Texas. Theyalso modeled energy performance in seven climates with four different basewindow configurations. Results: How did Low-e filmperform in M&V? 29%AVERAGEPERIMETERHVAC SAVINGSwith single-paneclear glass. BETTERTHERMAL COMFORTOccupants reported superiorcomfort in both summer andwinter. 2-6 YRPAYBACKwith single-paneglass; installed costof $7.75 sq. ft. Whole building energy savings is estimated to be at least 1/3 of perimeter savings. Deployment: Where does M&Vrecommenddeploying Low-eFilm? ACROSS ALL CLIMATE ZONESBiggest efficiency gain and fastest payback will be in buildings with either singleglazing or existing applied film that is low performing or nearing the end of its(~15 year) service life.Also consider for lower-performing double glazing that does not already have alow-e coating between panes. [PDF - 272 KB]


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