ET25SWE0043 - Multifamily Central Heat Pump Water Heater Storage and Control Strategies for Increasing TSB

Central heat pump water heater (“CHPWH”) systems and load flexibilities are an important technology to achieving beneficial electrification cost effectively to support California’s climate mitigation goals. Water heating energy use in multifamily buildings with five (5) or more units accounts for 32% of total energy use based on a 2015 Residential Energy Consumption Survey by the United States Energy Information Administration (“U.S. EIA”). The 2022 Title 24 Statewide All-Electric Codes and Standards Enhancement (“CASE”) research suggested central domestic hot water (“DHW”) systems are common in most multifamily buildings. Properly designed and controlled heat pump water heater (“HPWH”) systems are energy efficient and can reduce greenhouse gas (“GHG”) emissions compared to the natural gas-fired alternatives.

Decarbonization policies and the urgent need to reduce renewable energy curtailment costs are driving the development of load flexible technologies for HPWHs. In 2023, the California Energy Commission (“CEC”) established a goal of using load shifting or load flexibility to make up to 7,000 megawatts (“MW”) of electricity by 2030. Senate Bill 49 gives the CEC the authority to set flexible demand appliance standards and labeling requirements for equipment, including HPWHs.

A recently completed CalNEXT project (ET22SWE0017) showed that an average load shed of 32 –63% during the peak period was achieved with improved control for two (2) multifamily CHPWH installations (1). Previous field demonstration projects showed the estimated energy savings range from 0.15 to 0.7 kWh peak demand savings per customer (BPA Pilot, 2018, PG&E and PNNL Pilot, 2021, Mitsubishi, 2023). A study conducted by the Natural Resources Defense Council (“NRDC”) concluded, “HPWH demand flexibility represents an important opportunity to help integrate renewable energy, and reduce GHG emissions, customer costs, and grid costs.”

Policy and programs play a crucial role in enabling load flexibility while addressing potential conflicts of interest between grid operators and building owners when participating in load flexibility initiatives. This project aims to inform policies and programs on the impacts of improved load management with CHPWH on customer load profiles, building-level electrical infrastructure, and grid demand. Additionally, it seeks to provide recommendations for enhancing existing programs to incorporate energy storage solutions for load management and incentivize designs that optimize load flexibility.