Code Changes and Proposal Discussions Open Tacoma Glass ConferenceJuly 26th, 2023 by Ellen Rogers
Tacoma, Wash., is home of world-famous glass artist Dale Chihuly. This week it’s also a home-away-from-home for the architectural glass industry, which is gathered for the National Glass Association’s Glass Conference. The event, which runs through July 27, includes technical committee meetings, educational presentations, code reports and more.
Code consultants Nick Resetar and Tom Culp opened the day’s agenda with a look at some upcoming proposed code revisions. Resetar offered a look at some proposed changes to chapter 7 of the International Building Code, which relates to the fire action committee. He said one change to table 716.1(2) is the only proposal the industry will work to keep out of the code. It clarifies fire rated glazing requirements for sidelights and transoms and includes a footnote that permits fire resistance glazing tested to ASTM E119. Resetar said since this is already permitted in the current table, adding a footnote will create confusion, so they will recommend keeping that out of the code.
Culp also provided an update on energy codes. He said the industry is continuing to see a growing focus on energy efficiency and an overall trend toward net zero. Both the International Energy Conservation Code (IECC) and ASHRAE 90.1 now have goals to achieve net zero by 2030-2031. He added that in addition to significant increases in energy efficiency requirements, the move to net zero will also need renewable energy requirements, including BIPV.
Speaking of the 2024 IECC, Culp said the draft has gone through two rounds of public proposals and is now starting a “clean up” round to be completed this fall. On the commercial side, the code is looking at new on-site renewable energy requirements and an option for off-site renewables if necessary; new additional energy credits requirements; new thermal bridging requirements; tighter air leakage and increased testing; and an optional net zero appendix that can be adopted, among other changes.
On the residential side, there is a consensus agreement to advance fenestration criteria, but IECC isn’t willing to go so far as matching the requirements established for Energy Star 7, which is set to take effect in October. Instead, current maximum assembly U-factor ratings range from 0.27 to 0.50 across eight climate zones, while solar heat gain coefficient (SHGC) ratings range from 0.28 to 0.40.
Culp also discussed some of the changes happening within some of the local codes. Speaking of the 2025 California Title 24, for example, he said there are no changes to the main fenestration criteria, but the code is adding new mandatory backstops on vertical fenestration that are analogous to what they have for insulation and those cannot be traded off, even if demonstrating the same overall energy performance. Small adjustments to the code for single-family homes are designed to closely parallel Energy Star 7.0. An early proposal called for lowering U-factor requirements for all climate zones from 0.30 to 0.28. Now those requirements are expected to decrease to 0.27 in all zones other than California Zone 7, which includes San Diego.
In Massachusetts, the state’s Energy Stretch Code puts extremely aggressive requirements on curtainwall and window wall construction. The prescriptive path is limited to small commercial projects (less than 20,000 square feet). Other projects must demonstrate very aggressive overall building performance, and glazed wall systems must meet mandatory 0.25 U-factors that can’t be traded off.
“That is very tough,” Culp said. “It will require very advanced performance in both vision and spandrel … or reduce the use of curtainwall and the window area and switch to punched openings … and that’s the biggest concern.”
Culp said Massachusetts did give an “accommodation” of U-0.30 if using thermally broken frames, triple glazing with two low-E coatings, argon, warm-edge spacers and a center-of-glass U-factor of 0.14.
Optimistically thinking, Culp added, “Could this be what finally transitions the markets to triple glazing and VIG?” If so, he added, the question becomes will the owners pay for it or will it lead to the use of less glazing in buildings?
New York also has a similar stretch code. The original proposal called for U-factors down to 0.18-0.22, but Culp said that will likely go to 0.28 for fixed and 0.32 for operable windows. This code is aggressive, he pointed out, and will need advanced systems in both vision and spandrel areas, but is more realistic and flexible than what was originally proposed.
The Glass Conference continues this week with meetings and presentations.