A peculiar thing happened to window manufacturers as Congress was debating President Barack Obama’s economic stimulus package: The industry ended up with stricter standards that left some members very unhappy.

The bill, the American Recovery and Reinvestment Act of 2009, which the president signed in February, includes a provision that gives homeowners a 30 percent tax credit for the costs of qualified energy-efficient home improvements (with a cap of $1,500 per home).

But the credit only applies to replacement windows, doors, and skylights, and products must have a 0.30 U-factor and a 0.30 solar heat gain coefficient (SHGC) to qualify. The Schaumburg, Ill.–based American Architectural Manufacturers Association (AAMA), which represents window and door makers and other companies in the fenestration industry, says the threshold is too high.

“As it’s currently written, the stimulus bill sets a somewhat arbitrary standard that not only eliminates the majority of proven energy-efficient window, door, and skylight products available today, but also fails to take into account distinct differences in performance required by different climatic regions in our country,” Rich Walker, president and CEO of AAMA, said in a March 3 statement.

The organization, instead, prefers using Energy Star as the basis for tax credit qualification. But the DOE—which was already working on new guidelines to make Energy Star requirements tougher—issued some unexpected changes. As a result, the industry will be facing stricter standards anyway, beginning Jan. 1, 2010.

“There were two things [the DOE] was trying to do: toughen up Energy Star and expand the number of zones so that it was more customized geographically,” says Dave Koester, brand manager for Medford, Wis.–based WeatherShield Windows and Doors. “In essence, the big shocker for everybody was that they were going to move the U-factor in the northern part of the U.S. from 0.35 to 0.30. This was a huge move.”

“The tax credit in the American Recovery and Reinvestment Act of 2009 specified energy performance criteria … for the entire country, regardless of climate zone,” Richard H. Karney, Energy Star products manager at the DOE said in an April 7 letter to stakeholders. “DOE considered this fact when reviewing Energy Star criteria levels across the country, but tightened the U-factor criterion to the 0.30 level of the tax credit only in the North.”

In addition, the expanded northern zone on Energy Star’s climate map now covers almost half of the country, Koester says. The new requirements take effect Jan. 1, 2010.

From the DOE’s point of view, Energy Star is the standard bearer and its requirements should reflect that. Currently, more than half the windows on the market meet the current criteria for Energy Star certification. Because of the apparent ease in meeting the standards, the agency felt they were not strict enough.

“[Karney’s] goal that he indicated to window manufacturers was that he wanted no more than 25 percent of all windows meeting the standards,” Koester says. “His feeling was, if just about everybody can [meet the standard], it’s not that great.”

But some window and door manufacturers are displeased with the timing of the new criteria and decry the fact that it was influenced by the language in the stimulus bill. “Due to severe economic conditions and confusion with the stimulus tax credit, there is consensus that the implementation should be delayed until the tax credit is out of play,” Walker says.

The association has encouraged the DOE to consider changing the criteria to include three climate zones instead of four; align the window solar heat gain coefficient for Climate Zone 1 with the tax credit for doors and skylights at a value of 0.30; and consider all doors to be in the same category, regardless of their operation.

Moreover, AAMA requested a U-factor stretch of 0.03 for high-altitude applications, where a breather tube may negate the thermal performance improvements provided by inert gas fill. For the northern zone, the association recommended that the alternative SHGC trade-off criteria (=0.40) for a U-factor of 0.32 be reduced to a SHGC of =0.20 or =0.25 to allow for the use of higher-performing glass that is currently available.

Energy Star is a voluntary program so manufacturers aren’t required to comply, but in a market that has seen interest in energy efficiency and green building, failure to meet the standards could weaken a company’s market position.

It’s likely that most large window manufacturers and some small ones will have products that meet the new rules and should have little trouble. Vinyl and fiberglass windows, Koester says, will easily pass the new threshold, but some manufacturers who make extruded aluminum-clad products will have a hard time. “It will present a serious challenge for some of those manufacturers,” he says.