U.S. Department of Energy - Energy Efficiency and Renewable Energy
Building Technologies Office – High Performance Windows Volume Purchase
For Residential Buyers
Both home owners and buyers can take advantage of the energy savings from windows available in the volume purchase program. High performance windows can reduce the average heat loss through windows by over 30% 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.
A lower U-Factor in highly insulated windows may render perimeter heating near windows unnecessary.
Radiation from a warmer body to the colder glass causes discomfort because the two sides of the body have very different rates of radiant heat loss
Wisdom Way Solar Village
One successful example is Wisdom Way Solar Village, a small residential development comprised of 10 duplexes in western Massachusetts. These homes were designed and built to showcase energy-efficient building performance at affordable price points. Duplexes of this project range in size from 2-bedroom units at 1,137ft² to 4-bedroom units totaling 1,773ft². Successful use of triple-pane high performance windows in concert with an improved overall building envelope allowed for the scale-down from a conventionally sized heating system to a 12,000 Btu natural gas unit. This heating unit reduction represented a $4,500 savings in the total cost of the system. Additionally, due to the superior insulating properties of the windows and overall envelope, occupants can expect to save over $1,000 annually on energy. Despite a $7,000 incremental cost for an enhanced building envelope—$3,500 of which was spent on window upgrades—achieving building performance that allows for a more compact heating system can offset much of this incremental cost and significantly reduce the payback period.
More Advantages for Residential Buyers
In cold and mixed climates, home buyers can save energy and money through the use of high performance windows, which may result in considerable savings from a lower heating bill. Homeowners can cost-effectively lower lifetime energy costs, while improving temperature uniformity and room comfort, and potentially acoustic characteristics. Depending upon their structure, three pane high performance windows can moderately to significantly lower noise levels compared to standard two pane windows.
Lifetime (20 yr.) savings per 3' x 5' window with U-factor 0.22
Assuming a 3% discount rate after adjusting for inflation
Although presently high performance windows tend to be niche products that can be cost-prohibitive, there is a large energy and cost savings potential from volume demand and supply.
In the Future
The Buildings Technology Program (BTP) will be providing additional support to help successfully transform the market for high performance windows. This support will include a follow on manufacturer production engineering solicitation to further improve performance and drive down costs, addition of commercial-grade high performance windows, a Phase II volume purchase, and visibility and recognition mechanisms for builders who routinely install high performance windows.