Characterization of Central Heat Pump Water Heating Deployment in the Multifamily Market

Water heating energy use in multifamily buildings can account for 27 to 32 percent of total energy use based on 2015 Residential Energy Consumption Survey by U.S. EIA. Heat Pump Water Heating (HPWH) systems use electricity to produce hot water by transferring heat energy from one source, typically air, to potable water. The 2022 Title 24 Statewide All-Electric CASE research suggested central gas-fired DHW systems are common in most multifamily buildings, except for those with a small number of dwelling units. Central HPWH systems (CHPWHS) are an important technology to decarbonize multifamily buildings. While a variety of residential HPWHs are available to the single-family residential market, CHPWHS are relatively new technology, with limited field installations in multifamily buildings in California. Field research is finding that many early HPWH installs in centralized applications with continuous recirculation systems before 2020 are not performing well. In a typical multifamily building where HPs have been installed and commissioned appropriately, the project often has endured steep installation and commissioning challenges and associated cost, and they are operating at a lower system COP than anticipated. There are several gaps that this study will address. There is a lack of comprehensive data on field HP system designs and existing installation practices. This study will identify system types and compare the configuration with established configurations listed by NEEA in their Advance Water Heating Specification publication. It will document the refrigerant used, water temperature parameters, storage volume and output capacity and storage vs. capacity ratio. This project will note operational data on what type and how HP controls are being utilized, how mixing valves are configured and if the systems use back-up water heating and how it is configured. If DHW system details are available for the retail floor in mixed use buildings, then it will be documented to get further insights and potentially identify additional gaps. Lastly, the team will document purchase and installation costs. This project will conduct a market characterization of CHPWH deployment barriers and opportunities for multifamily buildings. The main goal of this study is to understand implementation processes for retrofitting CHPWH systems in commercial and multifamily buildings, focusing on identifying cost-effective strategies, best practices, and overcoming barriers to increase adoption and enhance performance of the system. The project team will: (a) explore current installation practices for various configurations and preferred processes that enhance installation efficiency and system performance to understand the CHPWH adoption patterns (e.g., based on existing systems, building types, and regional climates); (b) analyze cost considerations and how utility incentive programs play a role in promoting CHPWH adoption; (c) investigate the standard testing and commissioning procedures for CHPWH systems; (d) and assess the CHPWH market structure to understand the business models, including the distinction between specialty HPWH contractors versus broader HVAC and deep retrofit services. The project team envisions this effort as one of three projects on CHPWH technology in multifamily buildings ultimately leading to new measure development or updates.