Massachusetts Stretch Codes to Target Buildings, Curtainwall

The commercial component of the updated building energy codes from the Massachusetts Department of Energy Resources (DOER) took effect in July 2023. The revised stretch codes include updates to the base code, stretch energy code (with regulations targeting curtainwalls, window walls and storefront windows), and net zero code. Massachusetts enacted its first stretch energy code in 2010.

According to code consultant Tom Culp, the updated stretch codes aim to improve vision and spandrel glass performance. However, the rules could reduce the use of curtainwall and window areas, prompting a switch to punched openings.

“We will not be able to design all-glass buildings anymore,” Andrea Love told the Boston Society for Architecture (BSA). Love is the director of building science at Payette and president of the BSA/American Institute of Architects (AIA) board of directors. “We must
look at the code first and then think about design—not the other way around. This is a shift
in how we design façades.”

The Massachusetts Commercial Stretch Code and opt-in Specialized Code state specifically that vision glass used in high- and low-glazed wall system buildings must have a
maximum whole assembly U factor of U-0.25. Low-glazed wall systems that are less than
or equal to 50% of the total above-grade wall area of the building’s thermal envelope must
comply with Equation 4-2a*. High-glazed systems need to comply with Equation 4-2b*.

Culp explained to attendees at an NGA meeting in late July that Massachusetts did offer 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.

*See regulations for more information.

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