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Committee advances two ERI tables for Washington residential code; renewables accounting deferred
Summary
The MVPE advanced two primary R408 ERI target tables (R408.51 and R408.52) to the Council for CR102 after PNNL modeling of housing prototypes; the committee deferred final decisions about how on-site renewables should count in ERI scoring for further analysis and public comment.
The MVPE committee voted to forward two primary ERI target tables for Washington’s residential compliance path (the tables labeled R408.51 and R408.52 in staff materials) to the full Council for inclusion in the CR102 rulemaking package. The tables summarize PNNL’s modeled Energy Rating Index (ERI) targets across multiple home sizes and heating‑system types.
Kevin Rose (Northwest Energy Efficiency Alliance) told the committee that NEEA contracted PNNL to model roughly 300 prototype homes across 11 home classes, five system types, two climate zones and two foundation types; for each prototype, the modeling generated an ERI value consistent with the state’s draft 2024 prescriptive requirements. Some cells in the delivered tables remain NA because PNNL prioritized modeling combinations that are most likely in the market and budget limited modeling of less‑common combinations. “We modeled the most likely selection scenarios,” Rose said; he added that interpolating or requesting additional PNNL runs are options if stakeholders identify high-priority gaps.
Stakeholders raised an important policy question about renewable energy: the national ERI method treats on-site renewables as a multiplier that can produce large ERI improvements, which can allow an otherwise‑inefficient building to meet an ERI target by adding on-site generation. Industry participants, including Patrick Hanks (BIAW) and Gavin Tenneld (WASIA), urged alignment so renewable accounting does not overwhelm efficiency requirements. Kevin Rose proposed either capping how much on-site generation can count (to mirror R406 prescriptive caps) or using the national two‑target approach (different ERI targets with vs. without renewables). The committee agreed to advance the two primary ERI tables and to continue work on renewables accounting during CR102 and at the Council level.
What it means: Advancing R408.51 and R408.52 puts the ERI compliance pathway into the Council’s rulemaking materials with PNNL’s modeled starting points. Builders and HERS/ERI raters will now have an opportunity to review the modeled targets and offer comments during the CR102 public comment period. The committee did not finalize how on‑site renewable generation will be credited in ERI; staff and stakeholders will develop additional proposals ahead of Council consideration.
Next steps: Staff will post the PNNL tables, note NA cells, and solicit public comment. Stakeholders may request interpolation or additional PNNL modeling for specific NA entries. The Council will consider the ERI tables in its CR102 package next week.
