Tacoma, Wash., is home to world-famous glass artist Dale Chihuly. This week it’s also a home-away-from-home for some in the architectural glass industry, which is gathered for the National Glass Association’s Glass Conference. The event runs until July 27 and includes technical committee meetings, educational presentations, code reports, and more.
Code consultants Nick Resetar and Tom Culp opened the day’s agenda by considering upcoming proposed code revisions. Resetar looked at some proposed changes to Chapter 7 of the International Building Code related 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 permitting fire-resistance glazing testing 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 continues to see a growing focus on energy efficiency and an overall trend toward net zero. The International Energy Conservation Code (IECC) and ASHRAE 90.1 now aim to achieve net zero by 2030-2031. He added that in addition to significant increases in energy efficiency requirements, the move to net zero would also need renewable energy requirements, including building-integrated photovoltaics.
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 looks at new on-site renewable energy requirements and an option for off-site renewables if necessary. Additional changes include additional energy credits requirements, new thermal bridging requirements, tighter air leakage and increased testing and an optional net zero appendix that can be adopted.
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.
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 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 vacuum insulating glass?” 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 would likely go to 0.28 for fixed and 0.32 for operable windows. He pointed out this code is aggressive and will need advanced systems in both vision and spandrel areas but is more realistic and flexible than originally proposed.
The Glass Conference continues this week with meetings and presentations. Stay tuned to USGNN™ for more news and updates as they are made available.