The glass and glazing industry continues its battle to maintain—and expand—its presence on the wall through the various national and international building codes and standards. Tom Culp of Birch Point Consulting is at the forefront of the industry’s efforts, and earlier this month at the Glass Association of North America’s Building Envelope Contractors (BEC) Conference in Las Vegas, he gave an update on new requirements and guidelines recently put in place.
The new “Energy Efficiency Standard for Buildings Except Low-Rise Residential Buildings” was published in October and is included in the 2018 International Energy Conservation Code (IECC).
Culp said the standard aims to reduce whole-building energy costs by 8 percent from 2013 and 34 percent from 2004. “The largest savings come from reduced lighting power allowances,” he said. “The second largest savings come from new fenestration criteria, which resulted from two years of analysis and successful negotiations.”
Broadly speaking, he said U-factors in the new standard were lowered from 3 to 24 percent across different climate zones based on available technology and cost effectiveness, “bringing them more in line with the IECC.”
Other changes include modest reductions in solar heat gain coefficient (SHGC)—from 0.25 to 0.22 in the new climate zone 0, and from 0.40 to 0.36-0.38 in the middle zones 4-5—as well as orientation requirements that encourage lower SHGC or shading on the west.
According to Culp, the new energy code went through “an intensive 15-month process” in which the hundreds of proposals were considered involving two public hearings, negotiations and online voting by code officials.
“Overall, we did very well,” Culp said in the interest of the Glass Industry Code Committee (GICC). He said five of six proposals from the GICC were approved, and 96 percent of proposals the GICC opposed were stopped.
“Forty to 45 percent of all proposals we actively supported were approved,” he said. “This was a better success rate than most, especially with the online voters disapproving 80 to 90 percent of proposals.”
According to his presentation, code changes include:
- Increased allowable skylight area when daylighting.
- Modest SHGC reductions in zones 4-5 to match 90.1-2016.
- Increased compliance flexibility in existing buildings.
- Envelope trade-off procedure allowed in additions and alterations, not just new buildings.
- Corrected language that would have discouraged window replacement in existing buildings.
What didn’t change:
- Glazing area requirements.
- Stopped proposal that would have prevented highly glazed commercial buildings from complying even if they show the same or better energy performance.
- Stopped residential proposal that would create incentive for reduced window area in homes.
- There were no changes in commercial U-factors.
- “IECC had already leapt way ahead back in 2012, whereas 90.1 made more steady changes in 2013 and 2016,” said Culp. “Both are pretty even now.”
- He added that this “stopped a flawed proposal that would have required all commercial buildings one- to three-stories to meet residential U-factors for fixed and operable windows.
- Stopped proposals to lower SHGC beyond 90.1 and to restrict shading credits.
Culp added that in the new code, the IECC didn’t accept the updated climate zone maps from ASHRAE. “This could create confusion in many locations,” he said. “For example, a city can be in zone 4 for IECC and zone 3 for ASHRAE. This will hopefully be cleaned up in local adoption process.”
IECC also didn’t accept a proposal requiring either a whole building air leakage test or air barrier commissioning, which is in ASHRAE 90.1-2016.
2018 International Building Code (IBC)
Culp said the 2018 IBC was updated to reflect ASCE 7-16 “ASCE Minimum Design Loads and Associated Criteria for Buildings and Other Structures,” which increased design loads for skylights and sloped glazing, as well as risk category-four buildings.
Other changes include:
- Allowance of glass balusters with no top rail.
- This previously required special approval by building officials (note: it must be laminated).
- Special approval is no longer required if tested to remain in place after breakage in accordance with ASTM E2353, the glass railing standard.
- Clarified deflection limits for framing supporting glass consistent with AAMA TIR-11, especially for larger spans of more than 13½ feet supporting multiple lites of glass.
- Storm shelters are required for new schools and emergency operation buildings in tornado-prone regions.
- These need two-hour fire barrier segregation, and glass must meet impact standards or use shutters.
Culp added that the new IBC did not update to the 2016 accessibility standard (ANSI/ICC A117).