Remodelers who are particularly environmentally conscious may have already noticed that, starting at the end of August, the criteria for Energy Star-certified windows, doors, and skylights changed.

The biggest difference is in the Energy Star map (below), which now divides the country into four regions instead of three. The new North/Central climate zone covers a small band of territory from Virginia to New Mexico, while the South/Central zone -- where heating and cooling remains about the same throughout the year -- stretches from North Carolina west, encompassing all of California. The Northern zone is still the largest, dipping down into Arizona, and the Southern zone has shrunk, covering just the most tropical points between Florida and Texas.

The new standards also alter the U-factor and Solar Heat Gain Coefficient for the regions (see table below). One of the biggest impacts from this is that windows that have hard-coat low-emissivity coatings now meet the Energy Star requirements in the two northernmost zones. Previously, such windows could only be used in the Northern zone and still receive the Energy Star rating.

According to Richard Karney, Energy Star program manager at the Department of Energy, these adjustments were made to keep up with changes in energy codes that started going into effect in January 2001. "One of the auspices of Energy Star is to meet or, preferably, beat the energy codes," Karney says. Once the code changes were announced, the Department of Energy began talking with manufacturers about what changes might be feasible given advancing technology.

Starting this fall, the Department of Energy announced new zoning for the Energy Star map and new standards for windows and doors.

Courtesy Department of Energy

Map: Courtesy Department of Energy