Highly-Insulating (R-5) Windows and Low-e Storm Windows Volume Purchase Program

The U.S. Department of Energy's Building Technologies Program (BTP) is coordinating a volume purchase of R-5 windows, and low-e storm windows, to expand the market of these high efficiency products.

Price is the principal barrier to more widespread market commercialization. The aim of this volume purchase initiative is to work with industry and potential buyers to make highly insulated windows more affordable.

Read more at the U.S. Department of Energy >

For Residential Buyers

Both home owners and buyers can take advantage of the energy savings from windows available in the volume purchase program. R-5 windows can reduce the average heat loss through windows by 40% over common ENERGY STAR® windows with an R-3 value, and low-e storm windows have the potential to double the energy savings over storm windows without a low-e coating. In addition, home buyers today can take advantage of new home buyer tax credits ($8,000 for first-time home buyers and $6,500 for repeat home buyers meeting the tax credit criteria), that unlike the tax credit enacted in 2008, does not have to be repaid. Home buyers can then purchase highly insulating windows for home energy and cost savings and receive up to a $1,500 tax credit for those purchases (the tax credit is not applicable to all ENERGY STAR® windows).

Read more at the U.S. Department of Energy >

For Builders

In order for the volume purchase to succeed, the participation of national builders is a must. Specifically, the DOE Building Technologies Program (BTP) is requesting input on the types, sizes, and quantities of R-5 windows of interest along with permissible price premiums and warranties. Most importantly, BTP is requesting the commitment of national builders to purchase R-5 windows in volume if prescribed performance and cost specifications are achieved.

Read more at the U.S. Department of Energy >

More Advantages for Builders

In cold and mixed climates, builders can reduce capital costs through the use of R-5 windows which may permit elimination or redesign of perimeter duct heating systems, and installation of smaller HVAC units. Horizontal bar chart comparing typical winter window heat loss in Btu/ft2/hr for 3 window types in 4 U.S. cities. The top bar represents a conventional 2-pane window; the middle bar represents a typical ENERGY STAR window, and the bottom one represents an R-5 window. In Boston, MA, the top bar is > 40, the middle >30, and the bottom < 20; in Cleveland, OH, the top bar is > 35, the middle > 25, and the bottom > 15; in Minneapolis, MN, the top bar is nearly 50, the middle > 35, and the bottom > 20; in Spokane, WA, the top bar is > 45, the middle is about 35, and the bottom > 20.


The rate of heat loss determines the window surface temperature and the need for perimeter heating.

Highly insulating windows also allow builders to pitch market differentiation and a green edge. Home and business owners can cost-effectively lower lifetime energy costs, while improving temperature uniformity and room comfort, and potentially acoustic characteristics. Depending upon their structure, three pane R-5 windows can moderately to significantly lower noise levels compared to standard two pane windows.

In the Future

BTP will be providing additional support to help successfully transform the market for R-5 windows. This support will include a follow on manufacturer production engineering solicitation to further improve performance and drive down costs, a Phase II volume purchase, and visibility and recognition mechanisms for builders who routinely install R-5 windows.
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