U-Factors for Climate Zones 6 and 7 Debated at ICC Hearings; Proposal Denied

The International Code Council’s Building and Energy Conservation Code Committee heard a proposal from Craig Connor of Building Quality, representing himself, to change the fenestration U-factor in Climate Zones 6 and 7 to “0.32 or 0.35 if SHGC ≥ .45,” in Table 402.1.1 (Insulating and Fenestration Requirements by Component), and to .32 in Table 402.1.3 (Equivalent U-Factors). Both tables appear in the International Energy Conservation Code.

Connor proposed the same changes be made to the corresponding tables in the International Residential Code, Table N1102.1 (Insulating and Fenestration Requirements by Component) and Table N1102.1.2 (Equivalent U-Factors. For Tables 402.1.1 and N1102.1. Connor also proposed a footnote that the SHGC factor would be the value tested by the National Fenestration Rating Council.

In the current codes, .35 is the noted U-factor for Climate Zones 6 and 7 in both tables.

Connor said his proposal was designed for energy purposes.

“This is one of those opportunities to save some energy here,” he told the committee.

Thomas Culp of Birchpoint Consulting LLC spoke in favor of the proposal too on behalf of the Aluminum Extruders Council.

“This proposal increases the energy-efficiency of windows in the North, and they do it in a way that provides flexibility,” he said. “It encourages you to use the right glass in the right place. We believe it’s a good change.”

Chuck Andersen, codes and industry affairs manager for the American Architectural Manufacturers’ Association, stressed that the proposal provides flexibility.

“One of the key things here, folks, is that this is an option,” he said. “It doesn’t change the way you do things now. It gives you an alternate compliance path.”

However, opposition was present too. Ken Nittler of Enercomp said he wasn’t sure the change to the code would really provide energy savings.

“You have to be careful. There are many cases in many studies that show that a high solar heat gain product may not offset that [the product] has a worse U-factor,” he said. “Anytime there’s not direct sun on the window, that’s when you’re going to get your best performance.”

Mike Fischer, code consultant for the Window and Door Manufacturers Association, also noted the change might decrease the number of products that could be used in Climate Zones 6 and 7.

“These numbers aren’t an attempt to increase energy efficiency—they’re an attempt to decrease the number of available products,” he said. “I urge you as a committee to see through the subterfuge in the numbers and see that you’re getting something that doesn’t open up [the market]—it pushes certain windows out of compliance.”

He added that most windows today that were developed for the north have a U-factor of .35, so manufacturers would have to develop brand-new products to meet the new requirements, if accepted.

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