Published December 15, 2022
Effective March 1, 2023
The decarbonization of water heating has been identified as an achievable and significant step toward California’s overall decarbonization goals, and policies are changing to emphasize this end-use. Programs like TECH Clean California and BUILD are working on the market transformation of water heating and water heating manufacturers continue to make key strides in Heat pump products to address electrical infrastructure challenges and space constrained spaces.
The electrification of water heating presents a key opportunity to build demand flexibility into this added electrical load: this make-or-break moment could result in either added stress on California’s electric grid in the crucial evening hours or true success in bringing grid interactivity to the mass market.
Efficient, demand-flexible, electric water heating products designed to meet the hot water demands of residential households or buildings with similar water heating needs. This technology family will help meet the California Energy Commission’s goal of installing at least six million heat pumps (HPs) by 2030.
Unitary and Split-System HPWH for single family and individual multi-family dwelling units; low- Global Warming Potential (GWP) refrigerants for residential-duty HPWH.
HPWHs are a key strategy to building decarbonization by providing a cost-effective, all-electric water heating option, with significant electricity savings over resistance heating, with strong potential for demand flexibility.
Other greenhouse gas (GHG) emission benefits may be possible as the market shifts to low-GWP refrigerants, particularly as CO2 split-systems are currently available. Refrigerant leakage from unitary systems is expected to be low.
Higher adoption of HPWHs in higher-income households due to upfront costs suggest special considerations of equity to ensure that non-energy benefits (NEBs) such as reducing indoor exposure to combustion gases and ability to participate in load flexibility programs benefit all ratepayers.
Manufacturer product improvements may be able to create new designs and recommendations to facilitate adequate airflow and/or venting, increase output, decrease unit size (for space-constrained scenarios), and address known electrical barriers (deploying 110V/120V products, load management to match electrical capacity).
The technical performance of these products is generally well-known as there are mature testing and rating systems in place. The market is evolving as new products emerge, especially those which operate at 110V/120V electrical requirements. However, consumers and contractors will need targeted education as the default sizing metric of tank capacity is insufficient in comparing gas heaters and HPWH. Industry-wide transitions to first hour rating (FHR) or another metric to account for the lower British thermal unit per hour (BTU/h) ratings of HPWH will be necessary to ensure similar performance across products. Aside from this, HPWH have needs and features beyond the common gas storage alternatives that can make fuel-switching challenging:
Efficient, demand-flexible electric water heating systems for commercial applications (offices, pools, and food service) and multi-family residential (typically ≥5 dwelling units) applications.
Central HP water heater systems for multi-family, hotel/motel, food service, pools and commercial buildings; low-GWP refrigerants; dual-fuel water heaters.
Water heating is among the easier end uses to decarbonize with an all-electric HP option, with much less energy consumption than an electric resistance water heater. HPWH present the potential for greater demand flexibility with appropriate system design due to the variety of system configurations (tank size, output), and draw patterns.
Overall, HP would likely increase other emissions due to refrigerant leakage, but that may be mitigated as there is an industry-wide transition to low-GWP refrigerants.
Prospective ET studies should focus on: (1) improving the efficiency of all-electric centralized HPWHs; and (2) lab and field assessments of dual-fuel water heating w/ gas-fired HP sources to address the lack of product solutions for high-load, rapid-recovery applications such as food service.
Commercial-duty HPWH are still in a nascent technological stage that continues to change as the market evolves. Electrical infrastructure and installation limitations can prevent fuel-switching in retrofit applications with existing gas-fired hot water systems. New programs have only begun to scratch the surface of addressing barriers to adopting commercial HPWHs.
Potential barriers studies should address:
Methods for realizing the promise of HPWH as a broadly adopted, turnkey, high-impact GHG reduction technology with the most positive (and least negative) impacts possible on hourly electric capacity and ramp-up issues.
Distributed energy resource (DER) impacts of water heating; grid and utility integration for connected water heaters; financing mechanisms; deployment interventions; behavioral programs; etc.
This technology family will look to actualize the enormous (and growing) potential for load shift, shape, and shimmy: load management from scale of day to half-hour, and the resulting GHG reduction from shifting the heating schedule(s) to times when the electricity grid has a lower marginal emissions rate and cost to operate. These market interventions should look to ensure equitable access to the financial benefits as well as the associated NEBs.
Prospective ET studies should investigate (1) innovative program designs that can bring benefits of HPWHs to disadvantaged communities; (2) innovative program designs to ensure the multiple value-streams of efficiency, decarbonization, and grid-integration are all actualized; and (3) pilot demonstrations to validate emerging flexible demand appliance standards under CA SB-49 (Skinner).
Current deployment barriers can embody multiple interventions: tariff innovation, demand response (DR) enrollment, control algorithm selection, equipment incentives, financing options, and custom design choices. The development of combined deployment solutions with ongoing demand program enrollment plus additional financing, permitting, and installation assistance should be prioritized.
Prospective ET studies should address:
Design strategies and alternative heat sources to optimize energy efficiency, water conservation and GHG benefits.
Recirculation systems; heat recovery systems; external mixing valves; residential, commercial, and community-scale solar & geothermal water heaters.
Opportunities in this technology family will increase demand flexibility through thermal energy storage and optimization of mixing valve and hot water distribution setpoints. Prospective ET studies should include software solutions, design guides, or demonstrations that address:
Alternative hot water design strategies are an important approach to decarbonize many “hard-to-electrify” water heating scenarios. ET investments in this technology family can help bring greater awareness and highlight alternative decarbonization pathways.
Potential barriers studies should address:
Please refer to the Emerging Technologies Coordinating Council for a complete list of active and completed projects to ensure your project is not duplicative.