DOE Program Expands Market for Highly Efficient Windows

Since its launch in late May, the Department of Energy’s (DOE’s) Highly-Insulating R-5 Windows and Low-E Storm Windows Volume Purchase Program has made steady progress in increasing the market for efficient triple-pane windows and low-E storm windows.

Despite the amount of energy that R-5 Windows can save, they historically have had low market penetration, giving manufacturers little incentive to lower prices through economies of scale. The DOE program addresses supply and demand simultaneously, making it easier for customers to find the products and understand their benefits, while also building enough consumer interest to give manufacturers a reason to participate.

Energy Loss Through Typical Windows

Heating and cooling energy attributable to windows accounts for 4 percent of the energy consumption in the United States, or 10 percent of building energy. In the winter, windows are a prime source of heat loss because they typically are less insulating than other building components.

While the insulating properties of windows also are important in the summer, the biggest concern is unwanted heat from sunlight that can increase cooling needs. The DOE program focuses on two products designed to deliver energy savings by reducing heat loss through windows. Buildings in colder climates stand to gain the most energy savings from highly insulating windows.

Conserving Energy Through Efficient Windows

The program's window products are triple pane, with a U-factor of around 0.2. The windows must be rated with U-factor, and this translates roughly to an insulating value of R-5 (typical double pane windows are about R-2, compared with typical wall insulation of R-13 and attic insulation of R-30).

This extra insulation can yield significant savings. Replacing single-pane wooden windows with R-5 windows yields energy cost savings of $400/year in a typical 2,000-square-foot house in Boston. Upgrading from ENERGY STAR windows, which already are efficient, yields about $60 additional savings per year in Boston.

Low-E storm windows also improve energy efficiency by reducing heat loss. Whereas traditional storm windows have been around for decades, the addition of a low-E coating increases insulating properties. Using low-E storm windows instead of clear glass storm windows yields an extra $51 savings/year in a typical Boston home.

The program has generated strong interest among potential window purchasers. Before the program launch, more than 20 organizations submitted letters of interest, including major homebuilders, non-profits and weatherization agencies. The program's first webinar attracted more than 800 participants from different branches of the window industry nationwide. Subsequent webinars targeted specific audiences, such as weatherization agencies and public utility partners.

More About the Program

Find more information at the Windows Volume Purchase website and check out upcoming events. The DOE program is hosting several regional workshops where potential window purchasers can learn about the program, meet program staff, and see actual products.