GANA ASHRAE Subcommittee meets with ASHRAE on 90.1 revisions

Sahely Mukerji
January 27, 2010
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The Glass Association of North America’s ASHRAE Subcommittee, led by Chair Helen Sanders, senior vice president of operations, Sage Electrochromics, Faribault, Minn., met Jan. 15 with the ASHRAE 90.1 committee at the American Society of Heating, Refrigerating and Air-Conditioning Engineers winter meeting in Orlando, Fla. Representatives from GANA, the Aluminum Extruders Council, the American Architectural Manufacturers Association, Pilkington North America, AGC Flat Glass, Guardian Industries, Sage Electrochromics, and the Window & Door Manufacturers Association attended the meeting. AAMA, AEC, GANA/Glazing Industry Code Committee, Insulating Glass Manufacturers Alliance, National Glass Association and WDMA developed a united position before going into the meeting.

"While many decisions of the subcommittee were very frustrating, a strong presence really made a difference for the small gains we made, and equally important, avoiding any movement backwards,” said Tom Culp, president, Birch Point Consulting LLC, La Crosse, Wis.

The ASHRAE 90.1 committee is working on a revision to its standard 90.1 to increase building energy efficiency by 30 percent by 2030, including a proposal to reduce the window-to-wall ratio on the prescriptive path to 30 percent from the current 40 percent maximum. Other proposals will limit the light to solar heat gain ratio for the prescriptive path in the standard, and provide designers with a set of tables with new product U-value and solar heat gain coefficient requirements.

The following steps were taken at the meeting:
For perhaps the first time in history, the entire fenestration industry united on an issue, opposing the proposed reduction in window area allowed under the prescriptive path from 40 percent to 30 percent, Culp said. “We also gained significant support from the daylighting community,” he said. 

Sanders and Steve Treado, professor of Architectural Engineering at Pennsylvania State University, gave a joint presentation on how reducing window area could harm energy efficiency, especially with lighting controls. For example, depending on building type, even 50 percent WWR with lighting controls can use less energy than the proposed 30 percent WWR without lighting controls. This was followed by an independent presentation by Mudit Saxena, from the Heschong-Mahone Group, Sacramento, Calif., which largely supported the GANA subcommittee’s position looking at daylighting in real buildings they surveyed.

However, the proposed compromise that would accept ASHRAE’s 30 percent WWR as a baseline, but also allow up to 40 percent with either better performing windows or lighting controls, was rejected. The GANA ASHRAE Subcommittee worked on a second proposed compromise with further concessions, but this also was rejected, and/or was modified to a point that industry representatives could not support it. The U-factors and SHGC numbers promoted by the New Buildings Institute and the American Institute of Architects, and supported by the GANA subcommittee were tied into all the proposed compromises, but the ASHRAE envelope subcommittee refused to budge off of their current values.

Although the U-factor proposals were rejected, some of the subcommittee members did understand that the use of lighting controls can save significantly more energy than reducing glass area, or tweaking the glass type, Culp said.  “Many still think 30 percent is the optimum and were skeptical about even allowing a 40 percent path with controls, but on the positive side, they did push forward a proposed alternate path to allow up to 40 percent WWR with lighting controls.” This will go out for public review in February. However, it is far from ideal, as the high cost of controls will mean this path will mostly be ignored, and there are some technical concerns, Culp said.
 
ASHRAE also limited this 40 percent WWR option to nonresidential spaces and for climate zones 1-5, despite the GANA subcommittee’s data that it was applicable in Minneapolis and Anchorage. Separately, the Lighting Subcommittee is issuing a new proposal to require lighting controls in many more spaces, so combined with this proposal, those spaces could go up to 40 percent WWR if they upgrade to continuous dimming controls instead of just stepped photo controls. “Still expensive, but better, and the added controls do save significant energy ” Culp said.

Major concerns still remain. “We still maintain that the drop to 30 percent WWR was not properly justified, either with or without controls,” Culp said. “The lighting path is a step, but we still are concerned about the 30 percent WWR alone. This is especially true because in the end, addendum “bb” is moving forward to be in the 2010 version with a 30 percent WWR limit and no prescriptive option to 40 percent with or without controls.” The 40 percent WWR path with controls can’t be fixed in time to be in the 2010 version. “This is a real problem,” Culp said.

There were some other debated proposals related to VT requirements.  The GANA subcommittee lost the effort to apply the VT/SHGC requirement only where lighting controls are used, even though it pointed out that it doesn’t make sense to apply a restrictive requirement which results in zero energy savings unless there are daylighting controls in place. The ASHRAE committee argued that it should be required all the time to create “daylight-ready” buildings that may install controls in the future.  

ASHRAE officials agreed to change the VT/SHGC in the performance path from 1.5 to 1.1, to match the prescriptive path. “This will now give greater credit for daylighting when using the performance path,” Culp said.

The full committee approved going forward with a third public review of addendum “bb” with small changes. This included a change for metal buildings, and the modified VT/SHGC value in the performance path. This is expected to be the final round of comments, and “bb” will be completed in May for publishing in the 2010 version of the standard – assuming all appeals are resolved, Culp said.  

The 40 percent WWR path with lighting controls is going out for public review as a separate addendum. It has aspects that are controversial, so will possibly receive substantive public comments. It is unlikely to be completed in time to be included in the 2010 standard, Culp added.

Read more articles on this issue:
Closer look: Proposed revisions to ASHRAE 90.1 will have profound effect on industry
NGA comments on ASHRAE 90.1 public review
GANA opposes proposed revision to ASHRAE 90.1