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Tag raises minimum ERV/HRV efficiency and extends requirement into colder climate zone
Summary
The tag approved higher fan-efficiency and sensible recovery thresholds for heat/energy-recovery ventilators and advanced a requirement that ERVs/HRVs be installed in the state's colder climate zone (Climate Zone 5), citing short payback and public-health advantages for tight homes.
The residential energy code tag voted to raise the baseline recognized efficiency for heat- and energy-recovery ventilators (HRVs/ERVs) and to require balanced energy recovery ventilation in the state's colder climate zone.
Specifically, the tag approved proposals that raise the minimum fan efficiency used for equipment recognition to 1.7 cubic feet per minute per watt (CFM/W) and the sensible recovery efficiency (SRE) threshold in the component table from 65% to 67%. Mike Moore, representing the Home Ventilating Institute, told the tag the change is low-cost and rapidly payback: he summarized that bottom-quartile retail pricing for 67%-SRE / 1.7 CFM/W units is only marginally higher than lower-performing models, with a short payback for the consumer.
On a separate but related item, the tag also approved a climate-based requirement that balanced energy-recovery ventilation be required in Climate Zone 5 (the state's colder, higher-heating-demand counties). Kevin Rose of the Northwest Energy Efficiency Alliance explained the decision built on cost-effectiveness modeling and the stateregional climate context; proponents also noted filtration and indoor-air-quality benefits during wildfire seasons as a secondary public-health justification.
What the tag debated: Several members emphasized that ventilation measures are cost-effective only when paired with tighter building envelopes, and they asked for clear guidance on the interaction between the ventilation requirement and the air-tightness threshold used for energy credits. Commenters asked whether spot (single-room) ERV/HRV devices would meet the threshold and whether the change would push builders toward fully ducted systems; staff and presenters said the SRE and fan-efficiency thresholds are achievable by common ducted and high-quality spot units but that meeting the policy's intent will usually require system design appropriate to the house size.
Votes and next steps: The tag approved the HRV/ERV efficiency adjustments and advanced the Climate Zone 5 requirement in separate votes; the climate-based requirement passed on a roll-call vote after earlier debate (10 yes, 2 no, 1 abstain). Tag members directed staff to coordinate implementation guidance addressing interaction with air-tightness (ACH) thresholds and to publish recommended sizing and filtration guidance for jurisdictions and installers.
Ending: Staff will incorporate the revised SRE and fan-efficiency thresholds into the draft code tables and will draft implementation guidance for how ventilation systems should be selected and documented in Climate Zone 5 homes. The tag asked proponents to return with any additional data on cost-effectiveness in Climate Zone 4 for future consideration.
