VEIC conducted a study of the efficiency, load shift, and cost of residential non-phase change thermal energy storage systems integrated with combined space heating and domestic water heating heat pump systems at four single family buildings in California. The field study evaluated the performance of systems comprising of a commercially available air-to-water CO2-refrigerant heat pump, domestic hot water storage tank, air handler, a supplemental air-to-air heat pump for cooling and heating, and a proprietary control system.

The study assessed the appropriateness of such systems for existing and new California single-family homes in terms of cost to owners, cost to utilities, and public benefits. The results of the study can inform utility-sponsored programs for energy efficiency and load shift / load reduction.

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