Summary

The Government's Net Zero Strategy assumes that up to 11 million homes in the UK will use heat pumps by 2035. If heat pump users could consume less electricity during periods of peak demand, there could be less need for reliance on fossil fuels and expensive upgrades to the grid.

One method of reducing the consumption of heat pumps during periods of peak demand is through automation of smart thermostats, without requiring ongoing action from households. However, it is important to empirically test that this automation works and actually reduces demand when desired.

To address this need for evidence, we conducted a research project, called HeatFlex, in collaboration with innovation agency Nesta. We conducted a randomised controlled field trial from February to April 2024, where we remotely controlled participants’ heat pumps over 30 events lasting ~4-hours.

Key findings

Overall, our trial demonstrated that automated heat pump flexibility can result in meaningful reductions in household consumption, and could help reduce the impact of a growing need for electricity to heat residential homes in the future.

① We were able to shift household demand: we found a statistically significant 32% reduction (0.123 kWh) in household energy consumption during the flexibility period, when we directed heat pumps to produce less heat.

② We were able to reduce heat pump electricity consumption: we recorded a 74% reduction in typical heat pump electricity consumption (0.382 kWh) per half-hour during the flexibility window. We believe the above whole-household consumption reduction is smaller in magnitude than the heat pump-specific consumption reduction because many of our participants have solar photovoltaics and batteries.

③ Households were happy with the automation of their heat pumps. Participation in events was high: in only 9% of instances did participants opt out of events before they started

④ Participants were comfortable with the internal temperature of their homes. On average, the internal temperature in the homes of those who took part in HeatFlex events increased by 0.85°C during the two hours when we preheated homes before turning down the heat pumps for two hours. The internal temperature was still on average 0.16°C higher at the end of that second two-hour period, compared to the start of the preheating period.

While the sample was small (43 participants) and not representative of the current population of heat pump owners, our findings show that it is possible to reduce demand by operating heat pumps remotely, without compromising thermal comfort.