ICC Addresses 15-Percent Glazing Area Code Language

The International Code Council (ICC) 2016 Committee Action Hearings continued this week, with decisions made on a few notable glazing and fenestration industry-related proposals.

Wednesday, one relevant proposal—RE145—was narrowly defeated, while three others were approved.

The industry supported RE145. This relates to the performance path, in which the builder has flexibility to make changes in the proposed home design and just has to show equivalent energy performance to a baseline home built to the prescriptive path.

The current code penalizes window area above 15 percent. According Tom Culp of Birch Point Consulting, this means “you can do it, but have to make up for it by making something else more energy efficient.” Window area at 15 percent or below remains neutral. RE145 would have made the window area neutral in all cases, with no penalty or credit for any window area, even above 15 percent. “That matches the prescriptive path which allows any window area, and makes it simpler for the analysis,” says Culp.

Opponents of the change argued it would cause builders to increase window area. Proponents, however, cite a Pacific Northwest National Laboratory study for the Department of Energy that shows almost all homes are between 12 and 17 percent, and that “there is no evidence window area would be greatly increased, in part because of natural limitations such as cost and wall bracing requirements,” says Culp.

The initial vote was a 5-5, but the tie was broken by the chairperson, who voted to defeat the proposal.

RE146, meanwhile, was approved, 7-3. This sets the baseline window area at 15 percent, which keeps the same penalty for window areas above 15 percent, but now also gives a credit for lowering window area below 15 percent.

“This gives an incentive to reduce window area, which the window industry is obviously concerned about,” says Culp. “In reality, this will probably not change things too drastically in the real world, as homeowners want windows and no one wants to live in a cave, but this incentive could cause designers to take out a window here and there, and is a concern.”

Two other industry-related proposals—RE156 and RE134, were also approved.

Both set a “backstop” on the envelope, giving the flexibility to make changes in the traditional performance path or new energy rating index (ERI) path but also affirming that the envelope can only be traded off so much.

“This backstop says even if you exceed the energy performance in other areas like high efficiency equipment, use of solar panels, better lighting, etc., the envelope still has to be within 15 percent of the total area-weighted average of the 2018 prescriptive levels, and a modification also added that solar heat gain coefficient can be no worse than 0.40 in the southern zones,” says Culp. “For windows, doors, and skylights, this means that there is flexibility for compliance, but someone could not go so far as to remove the low-E and put in an inefficient, double-pane clear glass or single pane window, even if they make up for it elsewhere in the home.”

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