Examining daily electricity demand and indoor temperature profiles in UK social housing flats retrofitted with heat pumps

The UK Government has announced decarbonisation of domestic heating thorough low carbon heat pumps. This will result in the deployment of 5 million heat pumps by 2030, and over 25 million by 2050, thereby increasing seasonal and daily peak electricity demand and putting a strain on local electricity networks. Despite this, there is limited evidence on the impact of heat pump operation on daily electricity demand profiles. This paper empirically examines the impact of retrofitted ground source heat pump (GSHP) on daily electricity demand of six social housing flats co-located in a socially deprived housing estate in Oxford (UK) to understand the changes on daily electricity demand during the evening peak period (4-7pm). Concurrent time-series monitoring of electricity use, and indoor-outdoor temperatures was undertaken for one week before and after heat pumps installation during the heating season of 2020-2021. Contextual data about the flats was gathered using householder surveys and Energy Performance Certificates (EPCs). Pre-heat pump, electricity demand peaked during night time from 12am to 2am due to the use of night storage heaters. Post heat pump installation, mean indoor temperature and electricity demand profiles became more stable. While mean daily electricity use reduced by 42%, peak daily electricity use increased by 23%. Despite a small sample, the magnitude and timing of the peak period of electricity use varied. This reinforces the need for enabling flexible heat pump operation through time-of-use tariffs to bring value for local electricity network and householders.