MBPE forwards commercial energy‑code package to council after C406 overhaul, modeling plan

The MBPE committee forwarded the commercial energy‑code package to the Building Code Council on July 18, endorsing the tag’s extensive work on the C406 interactive credit tables and other updates and approving two clerical corrections.

Major change: C406 overhaul. The commercial tag substantially reworked the C406 credit-option tables (proposal 279), turning a single table into several interacting tables that aim to allocate credit values based on site energy. The tag’s intent was to combine the prior prescriptive heat‑pump prescriptive path and the fossil‑fuel path into a unified baseline so credit values could be awarded in graduated steps (e.g., appliances at code-minimum, 5% better, 10% better, etc.). The tag said modeling is necessary to set final point values for credits so the package tracks the council’s codified glide path toward 2030 goals.

Modeling and calibration: The tag secured modeling work by Pacific Northwest National Laboratory (PNNL), funded through NIA, to model how many points each option should be worth so the package meets the council’s greenhouse‑gas reduction glide path. PNNL’s modeling will calculate the interactive effects and produce spreadsheets and documentation to be posted on the Building Code Council website for public review. Staff said PNNL’s work may be posted with the council’s CR‑102 filing or very shortly thereafter.

Other notable changes and debates: - Glazing: The tag debated a requirement that at least 20% of glazing in many buildings use triple glazing. Proponents presented a cost‑effectiveness memo showing “thin triple” glazing can fit in conventional curtainwall/IGU systems and raise window performance with modest weight and cost impacts. - Steam humidification: The tag voted limits on steam humidification by climate zone (30% in zone 4C/5b west of the Cascades, 50% in zone 5B east of the Cascades) after concerns about Legionella and operational risks with adiabatic systems. - Contentious items: Three proposals drew sustained debate—mass transfer deck diagram (passed narrowly), adding a C406 credit for induction cooking (proposal 153; passed 9–6 with one abstention), and service-hot‑water replacement requirements for existing buildings (proposal 270; passed 7–4–1). The tag also flagged that three proposals passed with less than a two‑thirds majority; those items were highlighted for council attention.

Tag process and turnout: The commercial tag reported roughly 30 participants at each meeting, 14 formal meetings and more than 85 recorded hours, and about 163 proposals reviewed. The tag passed about 123 proposals (some modified), 21 failed, and 19 were withdrawn or consolidated. The chair stressed that most proposals passed by voice vote and few were highly contentious.

Committee action: The MBPE committee voted to forward the commercial package to the council with two amendments the committee had reviewed: (1) align the commercial code’s definition of “residential” with the residential code’s definition (so certain multiplex housing may choose either code) and (2) a clerical/cross‑reference correction (a February update). The motion passed by voice vote.

What’s next: If MBPE’s recommendation is adopted, the council will post the CR‑102 (and likely PNNL’s modeling results) for public comment; that modeling will be central to setting the final credit point values. The tag recommended posting PNNL’s work on the Building Code Council website for transparency.