Simulation based performance assessment of phase change enhanced thermal buffering for domestic heat pump load shifting

In this study, the feasibility of using thermal buffering enhanced with phase change material (PCM) to enable heat pump load shifting for a typical UK dwelling was investigated by comparing the performance of a buffered, load-shifted heat pump against a reference case. The impact of load shifting on a larger population of heat pumps was also explored.  The results indicate that with adequate buffering the operation of a domestic heat pump can be wholly moved to off-peak periods without adversely affecting space or hot water temperatures. The volume of the buffer required could be more than halved using PCM. However, load shifting was associated with a significant energy penalty that negated any economic benefits accruing from a switch to off peak electricity. The study also showed that load shifting of populations of buffered heat pumps could exacerbate peak loading on the electrical network rather than reducing it.