Measure Overview
This proposal seeks to introduce mandatory and prescriptive requirements in Sections 120.5 and 110.2, and JA2 for AWHPs. This measure includes two proposals: Limit the concentration of propylene glycol in some situations, and mandate AWHP/Water-to-Water Heat Pump (WWHP) isolation to align with chiller and boiler requirements.
Submeasure 1: Glycol Concentration Limits Place limits on propylene glycol concentrations, with adjustments based on climate zone and system type, reducing the negative impacts on heat exchanger performance and pump power associated with excessive glycol concentrations.
Submeasure 2: AWHP Alignment with Boiler and Chiller Requirements Similar to equipment isolation requirements for other hydronic plant equipment such as chillers and boilers, this measure would require preventing or minimizing the pump flow to any AWHP/WWHP that is in the off condition without impacting the flow to active units.
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The Statewide Utility Codes and Standards Team is conducting a survey to inform nonresidential code change proposals for the 2028 California Building Efficiency Standards (Title 24, Part 6).
In appreciation, we will send you a $20 Tango gift card or donate this amount to your local United Way upon completion of the survey.
Take the SurveyScope of Proposed Code Change
| Building Type(s) | Construction Type(s) | Type of Change | Updates to Compliance Software | Third Party Verification |
| Nonresidential | New construction, alterations | Mandatory | No updates | No changes to third party verification |
Justification for Proposed Change
A recent PG&E code readiness report and other similar studies have shown that AWHP equipment frequently realizes much lower efficiencies than advertised (as much as 37% lower). Opportunities exist to establish requirements in the code (and potentially during acceptance and commissioning) to prevent certain poor design and installation practices from being scaled in the industry as the hydronic heat pump product category continues to grow.
There are also some code-related obstacles to the widespread adoption of AWHPs. While there is a compliance option for AWHPs implemented in the compliance software, the requirements to meet this credit are unclear, hindering adoption. It has been difficult to get projects approved, as designers, plans examiners, and inspectors struggle to discern which requirements and forms to apply.
This measure will promulgate several best practices for design and installation of AWHPs to help ensure that the advertised performance is achieved in practice. Code language related to isolation of inactive units in multi-unit systems, which is already in place for chillers and boilers, will be adapted and applied to AWHPs. In addition, limits to glycol concentration will help improve heat exchanger and pump performance while protecting systems from freezing in colder climates. Additional verification tests will be required to demonstrate compliance.
The preliminary statewide energy savings for the first year from this measure are projected to be 4.24 GWh, which is likely underestimated since the savings were calculated for 4.5 million ft2 (new construction only) assuming 10% savings of HVAC and DHW end uses. The final savings will be recalculated based on a more thorough assessment of relevant installation mistakes and the resulting energy impacts. Final savings analysis will include all non-residential building types along with additions and alterations.
Relevant Documents
Round One Utility-Sponsored Stakeholder Meeting Materials
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The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.