Large Capacity CO2 Central Heat Pump Water Heating Technology Evaluation and Demonstration
Association for Energy Affordability
Recipient
Emeryville, CA
Recipient Location
7th
Senate District
18th
Assembly District
$1,727,301
Amount Spent
Active
Project Status
Project Update
As of the end of 2025, the central heat pump water heating systems have been successfully installed at four sites, and performance data is being captured, with one final site under construction. Performance data from these sites indicates the heat pump water heating systems are performing at or above expected efficiencies. The research team has completed multiple rounds of performance testing at one of the sites looking at returning recirculation water to different locations within the storage system, the results of which were indicated that should be possible (and possibly even more efficient) to eliminate the swing tank for some central heat pump water heating systems. Additional testing of this approach, as well as additional operations variations will be tested at subsequent sites. The grant period has been extended by 9 months to allow for co-leveraging of additional funding sources and collection of additional performance data on recirculation and load shifting impacts on system performance.
The Issue
The predominant fuel for heating hot water in California is fossil gas. As California's electric grid moves toward zero carbon resources, water heating will make up a majority of greenhouse gas emissions within buildings if gas remains the predominant heating fuel. Electric heat pump water heaters designed for single-family homes are available in the market place. However, there are very few central heat pump water heating products appropriate for multifamily buildings available in the United States--and none of these central heat pump water heating products use zero- or low-global warming potential (GWP) refrigerants.
Project Innovation
This project tests and demonstrates the field performance of a low-GWP variable capacity central heat pump water heating system in five multifamily building applications, each with a different design approach and configuration. The technology is highly configurable and has grid integrated controls capable of responding to time-of-use rates and enabling load shifting. The project provides field data to validate Title 24 Part 6 energy code compliance modeling assumptions and algorithms; and seeks to accelerate the market for low-GWP central heat pump water heaters by documenting best-class design and installation practices. The demonstrations are installed in and benefit low-income and disadvantaged communities.
Project Goals
Project Benefits
Electrification of water heating has the potential to reduce greenhouse gas emissions and provides an opportunity for grid harmonization through thermal load shifting. This project seeks to accelerate adoption of an emerging low-GWP central heat pump water heating technology to address the needs of a large percentage of California multifamily buildings. Field tests will validate system performance, and streamlined design approaches and installation practices will be developed and disseminated to increase industry adoption and proper application of this technology.
Affordability
This project could result in greater electricity reliability, lower costs, and increased safety. Electrification of water heating in multifamily buildings represents an opportunity for grid harmonization through thermal load shift.
Safety
Water heaters have traditionally relied on fossil gas to heat water. If not fully combusted, the gas produces harmful exhaust that can be detrimental to human health.
Key Project Members
Andrew Brooks
Subrecipients
Electric Power Research Institute, Inc.
New Buildings Institute, Inc.
Ecotope
Match Partners
Electric Power Research Institute, Inc.
New Buildings Institute, Inc.
Mitsubishi
Brightpower
