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January 27, 2014

Victory! ASHRAE withdraws addendum to reduce window to wall ratio

In response to ASHRAE’s addendum to the potential reduction of Window to Wall Ratio (WWR), an ASHRAE workgroup voted (18-1-1) to withdraw the proposed addendum. Therefore, for the time being, the dispute issues may be dropped. This will make the third consecutive stop of the WWR for the glazing industry.It has been reported that the 90.1 and 189.1 committees now want to focus on other areas, including promotion of high performance windows and daylighting. The victory is due to several glazing organizations (including GANA and FCA International‘s Architectural Glass & Metal Committee) and contractors working to vocalize concerns for reducing the window to wall ratio.

These groups attested to the fact that the core proposal to reduce glazing area remains flawed and technically unjustified, is inconsistent with other studies that have been presented, will harm indoor environmental quality, and is counter to high performance building design.  The groups stood firmly behind  comments and evidence that reducing window area by 25% is wrong and counter to the intent of high performance building design.

For example, GANA’s energy division said that “the underlying proposal to reduce glazing area remains without adequate technical justification or analysis, and cannot, simply, be fixed by adding a couple of exceptions, which if anything, only highlight problems with the original proposal.” While two of the proposed exceptions lessen the impact on restaurants and non-plenum buildings, “that’s putting a band-aid on a bad proposal that still harms other buildings and the manufacturers of numerous commercial glazing products without adequate justification.”

Furthermore, the exception to add a minimum VT requirement would only compound errors of the core proposal, and adds even more controversy. A minimum VT has been previously rejected by ASHRAE 90.1, ASHRAE 189.1, and the IECC, and is technically wrong, said GANA. As has been discussed before, minimum VT is an incomplete and incorrect metric for daylighting, which must include many other factors, and is inconsistent with the effective aperture approach already required in 189.1 and the IgCC. Finally, like the core proposal, there has been no technical analysis for ASHRAE 189.1 to justify the exceptions.