Managing the Load Profile: Study Shows Heat Pumps Cut Energy Use but Increase Peak Demand

A study by researchers Rohal Agrawal and Professor David Wallom, focusing on the real-world deployment of ground source heat pumps (GSHP) in a cohort of retrofitted UK social housing apartments, has quantified the impact of domestic electrification transition on the electricity grid. The research provides data that could be useful for policymakers, as the UK progresses lays out its net-zero roadmap, demonstrating both substantial energy savings and emerging infrastructural challenges.

The study presented a methodology to generate synthetic half hourly electricity demand profiles for UK house holds by integrating detailed sociotechnical data from SERL with heat pump usage patterns from the EoH project. By combining behavioural electricity consumption data with heating technology usage, the method enables high resolution simulation of seasonal and daily demand patterns under varying levels of residential heat electrification.

Significant Reduction in Mean Consumption

The study tracked energy consumption patterns during the heating season, validates the technology’s high operational efficiency. Compared to predecessor electric heating systems, the heat pump installations were associated with an average 42% reduction in the mean daily electricity consumption dedicated to heating.

The data also indicated an improvement in occupant comfort, demonstrating that efficient heat pump operation maintained more consistent internal thermal conditions for residents.

The Challenge of Peak Load

While overall energy consumption dropped, the analysis identified a critical issue related to the dynamic nature of demand, peak daily electricity use increased by 23% following the installation of the GSHPs.

This phenomenon is attributed to a fundamental shift in the electricity load profile. Demand moved away from the stable, off-peak hours (12 am–2 am) characteristic of older night storage heaters, towards a sharp, concentrated draw during the high-stress evening period (4 pm–7 pm). This new peak coincides directly with other high-demand household activities, raising concerns for the stability and capacity of local electricity distribution networks.

The Need for Active Demand Management

The findings underscore that the transition to electric heating necessitates active system integration, not merely component substitution. The research strongly concludes that the success of mass heat pump adoption hinges on implementing effective demand-side management (DSM) strategies.

To utilize the inherent thermal storage flexibility of heat pump systems and avoid overloading the local network infrastructure, policy must prioritize:

• Time-of-Use Tariffs: Utilising pricing signals to incentivize consumers to run heat pumps during periods of lower network stress.

• Smart Control Integration: Employing automated controls to modulate consumption, effectively "flattening the curve" of evening demand.

• A shift away from costly, widespread upgrades towards a more efficient targeted reinforcement strategy. By identifying “hotspots” based on local housing stock, network operators can prioritize investment in upgrading transformers and cables where the risk of overload is highest

The paper provides evidence that while heat pumps deliver on promises of efficiency, mitigating the inevitable strain on peak demand through smart regulatory and technological frameworks is essential for realising national decarbonisation goals.

Find out more

• Read the study. Electricity demand in electrified UK homes: the role of heat pumps, seasons, and property type