Washington residential energy TAG keeps several 2021 state requirements, rejects some 2024 IECC changes

The Washington State Residential Energy Code technical advisory group met virtually to review the integrated draft that will form the baseline for 2024 code proposals and to vote on whether to carry forward specific 2024 International Energy Conservation Code (IECC) provisions or keep the Washington 2021 state language.

The TAG, chaired by Kjell Anderson of the Washington State Building Code Council, spent the meeting reviewing the integrated draft — staff’s mash-up of the 2021 Washington State Energy Code and the 2024 IECC — and taking motions on draft wording and several substantive technical items that will affect the baseline document released by the Building Code Council for public proposals.

Why it matters: the integrated draft becomes the base document on which code-change proposals will be filed. Retaining 2021 state language — rather than adopting corresponding 2024 IECC language — preserves the existing baseline that local code officials, builders and utilities use. That choice changes which proposals are needed to achieve tighter energy performance or to allow trade-offs.

Key outcomes

- The TAG approved its meeting agenda and proceeded to a line-by-line review of the integrated draft.

- The group voted to revert the R101.3 intent language to the 2021 Washington State Energy Code wording rather than adopt the IECC intent language (motion by Kim Barker; passed). TAG members argued the IECC intent text could conflict with state RCWs and with Washington-specific objectives.

- The TAG removed the draft section R103 (code compliance agency) as unnecessary; members said enforcement is handled elsewhere and local jurisdictions already have authority (motion by Greg Davenport; passed).

- On the solar-ready/conduit language: a motion to remove the requirement for detailed routing of conduit and prewiring in construction documents failed at roll call (yes 10, no 2, abstain 2). Supporters of removal said routing is often adjusted in the field and documenting it is onerous; opponents said the documentation reduces retrofit costs and protects owners’ future options.

- On inspection language for wall insulation the TAG adopted the model-code inspection reference (R107.2.6) in place of a Washington amendment, and added interior-or-exterior inspection wording so exterior insulation assemblies are covered (motion passed).

- Thermal performance: after debate and a call to end discussion, the TAG voted to keep Washington’s 2021 ceiling and floor U-factor values (the TAG retained the WA 2021 values for ceiling and floor rather than use the IECC 2024 U-factors; vote: 10–5 with 1 abstention). Later, the TAG voted to use the lower wall U-factor (0.045) proposed in the IECC 2024 in place of the 2021 state value (motion passed 12–0 with 4 abstentions), so the integrated draft will reflect the model-code wall U-factor while keeping the state numbers for ceiling and floor.

- Performance path and baseline definitions: TAG members raised concerns that several 2024 IECC changes (including new baseline assumptions about HVAC, duct location, and equipment) could create a net rollback unless model-path thresholds are recalculated. The TAG voted to retain the 2021 Washington baseline language for the residential performance path (R405) rather than adopt the 2024 IECC text (motion passed 10–2 with 1 abstention). Members asked staff and stakeholders to analyze later whether revised thresholds should be proposed so the performance path remains equivalent to other compliance paths.

- Several editorial and formatting items were adjusted (definitions, cross-references, footnote placement) and some low-impact definitions that are not used in the text were removed.

What people said

- Anne Anderson pressed the TAG to consider adopting IECC Section 408 (the credit table) saying it offers flexibility; she noted RCW references and the Department of Energy’s efficiency findings for IECC 2024. TAG members replied the TAG’s job is to create a workable integrated draft, and that specific credit-table measures could be proposed through the code-change process if stakeholders wish to pursue them.

- On solar-ready drawings, Shane Nilles argued routing requirements are onerous for residential construction; opponents including Kevin Duell and Tom Balderston said the required markings cut retrofit costs and result in better installations. The roll-call vote failed to remove the routing requirement.

- On model-path baseline changes, Kevin Rose (Northwest Energy Efficiency Alliance as a non-Tag presenter during discussion) told the TAG that moving to different baseline equipment or duct assumptions in the IECC requires revisiting the required percentage improvements in the performance path, otherwise the change can act as a de facto rollback.

Next steps

The integrated draft approved during the meeting (with the TAG’s selections noted above) will go to the Washington State Building Code Council, which will publish the document as the base for the 2024 rulemaking window. That public proposal window will open after the council’s next meeting; once the council opens proposals, stakeholders may file code-change proposals for the 2024 adoption cycle.

The TAG repeatedly noted that any of the items it declined to accept today can still be advanced by a code-change proposal when the council opens the public proposal window. TAG members asked staff to flag the items the TAG considered “significant changes” so the Council’s reports and the public are clear exactly which state amendments remain and which model-code items were selected.

Ending note

Chair Kjell Anderson reminded the group that the integrated draft is a starting point to enable public proposals; it is not the final code. The TAG’s votes narrow the set of issues the public and stakeholders will need to address in formal code proposals.