Several glazing industry associations successfully appealed changes to ASHRAE Standard 90.1 that would have reduced the amount of glass allowed in commercial building envelopes. The change would have reduced the maximum window-to-wall ratio from 40% to 30% and tightened the maximum U-factor and solar heat gain coefficient. A minimum for visual light transmittance was also added to the standard?s prescriptive path. The standard is being returned to committee so the glazing changes can be reconsidered.
Thomas Culp, Ph.D., of Birch Point Consulting, who helped craft the appeal, says the addition of a visual light transmittance minimum ?would harm more than 50% of commercial glazing products?yet without any energy savings in most cases.? He says he will join the committee and looks forward to the opportunity to revise the glazing provisions. ?It has been a real challenge trying to educate the ASHRAE committee about modern glazing technology and the important role glazing can play in high-performance buildings.? He believes that the benefits of glazing?including daylighting?must be balanced with the energy drawbacks.