ASHRAE Compromises on Proposed Requirements for Glass in 2010 Edition of Standard 90.1
October 8, 2009

Several compromises were reached last week between the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Envelope Subcommittee and members of the glass industry during a meeting that took place on the 2010 revisions to Standard 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings. (CLICK HERE for related story.)

Stanley Yee of the Façade Group made a presentation to the group on behalf of the Glass Association of North America's (GANA) ASHRAE Subcommittee. "The main message of the presentation was essentially that the light to solar heat gain (LSG) criteria of greater than 1.5 essentially eliminated the possibility of using up to 60 percent of the high-performance glass products that are available on the market today," Yee explains.

The GANA presentation also pointed out that mandating LSG of greater than 1.5 could result in the misapplication of glass in the absence of considering significant environmental factors such as orientation and climate zone.

Another cause of concern for the GANA group was that there has been no definition for dynamic glazing in the updated ASHRAE standard. "Inadvertently, the proposal had basically eliminated the possibility of using dynamic glazing, which to the [GANA] group was rather intriguing considering that the Department of Energy has conceptually acknowledged that it is a step in the right direction as far as technology goes and trying to achieve net zero-energy."

In the end, the Envelope Subcommittee ceded some compromises.

"The end result was that they had reduced the 1.5 criteria to 1.25, center of glass," Yee says. In addition, he adds, "We were able to convince the Envelope Subcommittee to accept the criteria associated with using affective aperture."

He noted that the Envelope Subcommittee also opted to create a new track for outlining information specifically on dynamic glazing.

Yee is reluctant to call the compromise an outright victory, "Because," he says, "we haven't really assessed fully what the implications will be of what we've landed on."

Moreover, the ASHRAE Envelope Subcommittee made some new changes to the performance path in the proposed standard updates.

"What we're talking about is the prescriptive path, which is what probably 80 percent of the projects that get built in this country are based on," Yee says. "[For] the 20 percent on the performance path, or what's sometimes called the trade-off path, they increased the requirement. It used to be the same requirement as the prescriptive path."

Representatives from GANA, Guardian Glass, PPG Industries, AGC Flat Glass and Pilkington North America attended the meeting. GANA encourages other industry professionals to watch for the second round of public review of the standard, anticipated in January.

For more information, CLICK HERE to watch the Glass Association of North America's video podcast concerning this issue.

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