DOE Reveals Possible Revisions to Energy Star Requirements

October 1, 2007

The U.S. Department of Energy has sent a letter to stakeholders in the Energy Star windows, doors and skylights program officially announcing it is beginning a criteria review and revision process to set new requirements for products to carry the Energy Star label.

In the October 9 letter, Richard Karney, Energy Star program manager, notes that DOE is considering a variety of adjustments to the criteria. These include:

  • a substantially lower U-factor in Northern zones (initial target range: 0.20-0.30)
  • a minimum SHGC in the North to capture winter solar heat gain
  • a substantially lower SHGC in southern zones (initial target range: 0.20-0.30)
  • an insulating glass unit certification requirement
  • the addition of minimum VT criteria to ensure adequate light
  • a change in Energy Star climate zones to align them more closely with those in the 2006 International Energy Conservation Code
  • allowing SHGC/U-factor trade-offs in both the north and south to expand range of products
  • exploring emerging technologies such as dynamic glazings
  • the establishment of installation procedures to ensure performance.
Karney cites three reasons the DOE is pursuing a criteria change. First, he notes, improving energy efficiency is a national priority. Secondly, he points to the 2003 and 2006 editions of the IECC, and regarding prescriptive requirements for windows that are the same as Energy Star for either SHGC or U-factor in all states, 28 states have already adopted these codes. Finally, he points out, Energy Star is meant to provide product differentiation, but Energy Star labeled windows now make up more than 50 percent of the market. The Energy Star program has a target market share of 25 percent for all products.

“For its initial analysis, DOE is currently gathering data to determine what levels of energy performance are possible with the current technologies, the costs and technologies required to achieve various levels of performance, and the energy savings that higher performance products could deliver,” Karney writes. “DOE is also evaluating the potential impacts of proposed changes.”

The tentative timeline for the revision process includes an initial analysis scheduled to be concluded in December and distributed. A stakeholder meeting will be held in February 2008, with finalized criteria announced in March 2008. The earliest effective date for the new requirements is January 1, 2009.

Karney concludes by noting that the Department of Energy welcomes information about product availability and marginal cost. Input can be provided by contacting Emily Zachery at D&R International via e-mail at or by phone at 301-588-9387.