Measure Overview
This measure proposes to create a prescriptive pathway to require return-to-primary (RtP) configuration for split-system Heat Pump Water Heater (HPWH) systems in nonresidential (NR) buildings. This proposal would include an alternative pathway for products on the NEEA Tier 2 qualified product list, including standardized configurations and manufacturer’s requirements. The Statewide CASE Team would update JA14 – Qualification Requirements for Central Heat Pump Water Heater Systems to include new requirements for the design documents, installation, equipment and control start up, performance data reporting (COP, Defrost derate, Input power, Output Capacity, Refrigerant type, etc.), and RtP back up heating.
This proposal would apply to new construction, additions, and alterations of NR buildings in all CA climate zones. This requirement would apply to additions and alterations with a proposed water heater replacement with split HPWHs. The proposal does not require installation of HPWHs.
This proposal would require additions to the compliance forms, changes to the compliance software, and new plan check and building inspector activities.
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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, additions, alterations | Prescriptive | Update existing feature, add new feature | No changes to third party verification |
Justification for Proposed Change
The current NR prescriptive requirements for water heating do not include requirements specific to HPWH performance despite the increasing use of HPWH in NR applications. Due to air quality rules by the South Coast Air Quality Management District (SCAQMD) and the Bay Area Air Quality Management District (BAAQMD), future HPWH installations in California are expected to apply to about 61% of the NR building stock. This measure, which is focused on NR applications, draws on lessons learned from the development of multifamily (MF) requirements including recent research that indicates that RtP is advantageous over swing tank configuration in many cases. The proposed change is needed to establish a baseline configuration that ensures adequate hot water delivery and reduces energy use and energy costs associated with split-system HPWH in NR applications.
During the 2022 code cycle, in response to reliability concerns when split HPWHs were emerging, the Statewide CASE Team introduced the swing tank configuration as the baseline for new multifamily (MF) construction. However, recent lab tests performed by PG&E Applied Technology Services (PG&E, SCE 2024) to characterize the central HPWHs with recirculation show that RtP with R-134a can maintain reliability while reducing equipment requirements and increase Coefficient of Performance (COP) compared to swing tank configuration. The Association for Energy Affordability (AEA) performed field testing with large CO2 systems (Brooks, Neal and Young 2024) and found that RtP configuration operates at a higher COP and higher reliability compared to swing tank configuration. Additionally, AEA is currently conducting a series of demonstration studies for low global warming potential (GWP) HPWHs with recirculation for a Code Readiness project funded by SCE. If these tests show that the RtP configuration can maintain sufficient hot water delivery performance with high return temperatures for a broader range of refrigerants, they can further support this measure. The Statewide CASE Team expects to obtain the results in August 2025.
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.