Restaurant Field Monitoring

California’s restaurant sector consumes roughly 340 million therms of natural gas annually for water heating, yet faces major design, permitting, and operational barriers to electrification. This CalNEXT field demonstration evaluated a heat pump assist water heating (HPaWH) retrofit in a full-service restaurant that paired an air-source CO₂ heat pump water heater in series with an existing gas unit. The system achieved a coefficient of performance (COP) of 4.1, reducing on-site natural gas use by 93 percent and total water heating energy use by 76 percent while eliminating hot water runouts. Despite these savings, operating costs rose modestly (~$215 per year) due to high electricity rates and limited storage capacity. The project also exposed key permitting and structural barriers that slow HPWH retrofits in older facilities. Findings indicate that adding storage and pairing HPWHs with high efficiency, heat recovery dish machines can enable cost neutral decarbonization and load shifting. This field data informs revisions to health department sizing guidelines and supports targeted incentives in addition to proving it is a viable concept.