ET25SWE0050 - PCM Applications in Residential Water Heating

This project assesses the application, market opportunity, and performance of phase change material (PCM) thermal energy storage systems (TESS) to replace inefficient gas and electric water heaters located in space-constrained California multifamily buildings, or as a technology solution to reduce or eliminate recirculation losses in shared systems. Although not the primary focus of this project, the findings can be applied to single-family residences and manufactured homes with similar constrained water heater locations or recirculation systems. 

PCM thermal storage systems offer up to four times the energy storage density of traditional tanks and are compatible with solar thermal, heat pumps, and off-peak electric heating. PCM water heaters store and release energy by transitioning between solid and liquid phases, delivering performance comparable to tankless systems and supporting long-duration hot water needs. 

An assessment of PCM TESS applications in residential water heating will address several market barrier such as the absence of technical design and analysis for incorporating PCM water heating solutions to reduce recirculation and distribution losses; the physical limitations that prevent the installation of integrated heat pump water heaters (HPWHs); the performance challenges HPWHs face in recirculation systems; the lack of awareness and inclusion of PCM technologies in incentive programs; and the difficulty of deploying advanced systems during emergency replacements or in do-it-yourself (DIY) scenarios.  This research will include detailed market and technical analysis of existing PCM solutions, direct stakeholder interviews, cost analysis, engineering review, and building energy modeling to qualify the pathway and impact of utilizing PCM thermal storage to maximize efficiency and reduce costs in decarbonizing California's multifamily water heating.

This project will leverage active CalNEXT program studies researching the market opportunity for split-system HPWHs to address limitations of integrated HPWHs, as well as CalNEXT research on the applications of central HPWHs (CHPWH) and recirculation optimization in multifamily buildings.