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Code tag rejects ACI masonry thermal-bridging standard after extended debate
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Summary
The State Building Code Council's commercial energy code tag voted to disapprove two proposals to accept an American Concrete Institute (ACI) standard for accounting for concrete thermal bridges. Supporters said the standard would give designers options; opponents said it would weaken long-standing energy protections.
The State Building Code Council’s commercial energy code tag on Feb. 7 voted to disapprove two proposals from masonry industry proponents that would have incorporated an American Concrete Institute (ACI) thermal-bridging standard as an alternative method for calculating envelope performance.
The tag rejected proposal 204 in an 8-2 vote with four abstentions and then disapproved a closely related proposal, 205, 7-2 with five abstentions. Proponents framed the ACI approach as a practical, industry-developed compliance alternative; opponents said the changes would reduce the stringency of existing thermal-bridging protections in the energy code.
Why it matters: the energy code requires designers to account for conductive thermal bridges such as concrete transfers, cantilevered balconies and other highly conductive elements that bypass insulation. Tag members said the ACI standard would substitute a different set of default assembly values that, critics argued, can allow higher effective heat loss from concrete elements without requiring compensating improvements elsewhere in the envelope.
Proponent Carrie, representing the ACI-related group that drafted the standard, told the tag the document was developed to “enhance, complement, even go beyond” existing tables used in ASHRAE 90.1 and the IECC by offering more detailed factors for mass-wall assemblies. She said jurisdictions and design teams could use the tables as a reliable, code-adopted reference.
Opponents pushed back on several grounds. Tag member Dwayne Johnlin, after reading the standard, warned the proposal “significantly weakens what we've already got in place” and urged the tag to maintain protections that have been tightened over recent code cycles. Johnlin and others said the existing energy-code approach forces designers to identify and account for thermal-bridge areas so that the project must make up lost performance elsewhere in the building envelope.
Tag member Larry Andrews said the ACI proposal would expand structural options for designers, noting real-world construction challenges for items such as cantilevered balconies and transfer slabs. Andrews argued the standard could be useful for balancing structural needs with thermal performance, adding, “I really think we need to pass this along, and I wish we had another meeting so we could talk it over and see some examples here.”
Kevin Rose of the Northwest Energy Efficiency Alliance told the tag that a very similar proposal (CE30-24) had been presented to the IECC process for 2027 and was disapproved by national envelope subgroups, saying that history shaped his concern that adopting the ACI tables would lower code stringency.
The tag debated whether the ACI tables would be used only where ASHRAE or existing code tables lack values for a given assembly or whether designers could choose the least-stringent available set of default values. Several members warned the latter would create a de facto weakening of the state code, because designers would pick the most favorable table available to them.
After the votes, proponents and opponents agreed to document their technical and policy concerns for the next stages of the statewide rulemaking and public comment process. The tag’s disapproval means the ACI proposals will not be forwarded as adopted language; they may be raised later through other channels or in subsequent code cycles.
Details of the votes and next steps: proposal 204 was disapproved 8-2 with four abstentions; proposal 205 was disapproved 7-2 with five abstentions. Several tag members said industry and code advocates could pursue separate work groups or public comments to address technical gaps (for example, clarifying approaches for transfer slabs, slabs-on-grade and cantilevered balconies) without changing fundamental code stringency.
The tag’s action does not itself change existing state code text; it records the tag’s recommendation on whether to adopt the specific ACI-based alternatives presented in those proposals. The tag spent several hours on the topic and heard detailed technical and policy arguments from ACI proponents, energy-efficiency advocates and multiple tag members.
