Green Homes—Windows

NFRC‘s chief executive officer, Jim Benney, says, “It is important for consumers to understand the impact that windows have on their energy bills. By choosing the right windows for their climate, homeowners can save more than 30 percent on their annual energy costs.”

“The two most important measurements are the U-factor, which indicates the rate of heat lost through a window, and solar heat gain coefficient, which measures how well a product blocks heat caused by sunlight,” Benney says. For example, he says dual-paned windows with low-e coatings are typically 20 to 25 percent better than uncoated dual-pane windows. Using gas-filling and warm edge spacers (low-conductance spacers to reduce heat transfer near the edge of insulated glazing) along with the top-of-the-line low-e coatings can reduce U-factors to 0.30, a 40 percent improvement.

Benney says that today’s window frame materials that are more energy-efficient and low-maintenance include fiberglass, wood/fiberglass composite, other wood composites, vinyl windows, and vinyl and aluminum cladding, as well as thermally broken aluminum.

 

3. Visit the Efficient Windows Collaborative (EWC) website.
Check out the EWC web site, developed by DOE’s Windows and Glazing Program at the Lawrence Berkeley National Laboratory and the University of Minnesota's Center for Sustainable Building Research. The EWC is a coalition of manufacturers, research organizations, government agencies, and others interested in expanding the market for high-efficiency fenestration products.

Fact sheets provide details about different classes of windows for hundreds of locations across the country. A Window Selection Tool allows you to compare costs for a typical house by window type, city and more.