U.S. Department of Energy - Energy Efficiency and Renewable Energy

Building Technologies Office – High Performance Windows Volume Purchase

For Light Commercial Buyers

Significant energy savings from low-E window technology are possible in the commercial buildings sector where the current penetration of low-E technology is modest. Full adoption of low-E technology would save 0.4 to 0.5 quads over sales.

The Cambria Office Facility

A prime example is that of the Cambria Office Facility, a 34,500 ft² facility designed and built in Ebensburg, PA. This facility incorporates highly insulating, triple glazed windows at an incremental cost of $15,000 compared to traditional double glazed windows. These windows permitted the complete elimination of the perimeter heating system priced at $25,000.The air conditioning system was also downsized from 120 to 60 tons, saving $40,000 of which 15 tons or $10,000 was directly attributable to the triple glazed windows. Operating energy costs for this facility are less than a similar-sized office building in PA with traditional double-glazed windows.

More Advantages for Light Commercial Buyers

In cold and mixed climates, light commercial buyers can save energy and money through the use of high performance windows which may permit considerable savings from use of 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 high performance 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.

In the Future

The Buildings Technology Program (BTO) 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.