Volume 44, Issue 12 - December 2009



International Code Council Accepts Glass-Related Change Proposals

The commercial fenestration industry came closer to allowing AAMA 507 as an alternative to NFRC 100 and 200 than it has in previous attempts during the recent International Code Council (ICC) code change hearings. The proposal, which was supported by the American Architectural Manufacturers Association (AAMA), Glass Association of North America (GANA) and others saw increased support during this round of hearings, though it was defeated with a 6-5 vote. Proposal EC172 would have allowed U-factors and solar heat gain coefficients (SHGC) for storefront and curtainwall in commercial buildings to be determined with AAMA 507 as an alternative to NFRC.

“GANA representatives at the recent ICC hearings noted that some committee members who traditionally opposed using AAMA 507 as an alternative to NFRC for curtainwall and storefront ratings voted in favor of AAMA 507,” says Bill Yanek, GANA executive vice president.

Ken Brenden, technical service manager for AAMA, adds, “During previous testimony … analyzed actual data for nine different product types with 15 glazing configurations each found that the maximum variation between results obtained from the AAMA 507 method and the NFRC 100 and 200 methods that are currently referenced by the IECC was +0.003/-0.006. That’s a variation that is statistically insignificant.”

Several proposals were accepted, however. Among them, ICC approved a comprehensive proposal from the New Buildings Institute (NBI), American Institute of Architects (AIA) and Department of Energy (DOE) that will significantly increase overall commercial building stringency regarding the envelope, air leakage, HVAC equipment, lighting and commissioning requirements (EC147). This included an incentive to use onsite renewable energy systems.


A proposal from NBI and AIA (EC165) also was approved that decreased fenestration U-factors in several areas (see table above). All other proposals to reformat the U-factor table and remove the distinction between metal and nonmetal windows were disapproved. All proposals to change SHGC or impose minimum visible transmittance (VT) were defeated. The only SHGC change was a reformatting of the shading credit for overhangs.

EC165 brought about a big change in that the maximum glazing area allowed in the code’s prescriptive path was reduced from 40 percent down to 30 percent. “This may not actually save energy, but given the political environment and lacking any specific data, this was approved,” says Dr. Thomas Culp of Birch Point Consulting. He adds, “Larger glass areas can still be used, but the performance path must be used.”

On a positive note, ICC approved proposal EC173 and its new requirement for a minimum amount of skylights and daylighting controls in certain spaces, notably big box retail and warehouses. As Culp explains, “This helps to promote daylighting and glazing for saving energy. Many big box stores use plastic dome skylights for this purpose, but it will also increase the use of glass skylights in other spaces.”

These are preliminary hearings, and any item can change at the final action hearings in October 2010.

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