Nesta and the Centre for Net Zero (CNZ) published the results of a randomised control trial on 19 November 2024, finding that remote automation of heat pumps can shift electricity consumption away from peak demand periods while keeping homes warm. Half of the 43 volunteer homeowners recruited for the trial had their heat pumps remotely controlled for four hour periods1.
Nesta ran 30 events from February 2024 to April 2024, typically comprising a two-hour preheating period and a two-hour flexibility window. HeatFlex events typically occurred between 16:00 and 20:00 on weekday evenings, with the first two hours for preheating and the second two hours for the flexibility window1. The trial found that remotely controlling participants' heat pumps to flex consumption around peak demand led to an average 74% reduction of typical heat pump electricity consumption (0.382 kWh per half-hour across a two-hour window) and an average 32% reduction of typical household electricity consumption (0.123 kWh per half-hour across a two-hour window). Nesta states that the household figure is lower partly because many participants have solar panels and batteries, and that for households without these, overall demand reduction will likely be closer to the heat pump figure1.
The average internal temperature in the homes of those who took part in the four-hour events increased by 0.85C during the two hours when the homes were preheated before the heat pumps were turned down for two hours. The internal temperature was still on average 0.16C higher at the end of that second two-hour period, compared to the start of the preheating period1. Of participants surveyed afterwards, 81% said they were either "Satisfied" or "Very satisfied" with the temperature in their home, and only 9% opted out, typically because they were not going to be at home1. Participants were offered a £100 gift card as an incentive, alongside a free smart thermostat and a heat pump monitor to any households that needed them. Nesta contacted Octopus Energy customers in three geographical areas in which Octopus Energy Services could install the necessary equipment1.
On costs, Nesta cites recent empirical analysis by CNZ based on over 6,500 households, which found that even without third-party automation, a simple time-of-use tariff for heat pumps currently on the market is reducing annual energy bills by 18% (or £318) compared to a standard tariff1. A separate report released the same day from Cornwall Insight and commissioned by Nesta modelled electricity wholesale, network and policy costs associated with operating a heat pump flexibly in response to price signals through a range of tariff structures over a ten year period from 2024. That modelling finds households can make savings of up to £650 a year on the average annual electricity bill, when switching from a fixed heat pump tariff to a time-of-use tariff and flexing heat demand1.
"Heat pumps are the most efficient low-carbon alternative to fossil fuel boilers for keeping people's homes warm. Our experiment shows heat pumps could play a positive role in managing the energy system as more people use electricity for green heating, while also cutting people's electricity bills."
Why it matters for households
For a household with a heat pump, the trial indicates that automated control can move a large share of heating demand out of the evening peak without a measurable loss of comfort, based on the temperature readings and satisfaction responses reported1. That matters for heat pump controls because it suggests the savings from a time-of-use tariff do not depend on someone manually adjusting settings each evening. The trial's own figures show the household-level reduction (32%) was smaller than the heat pump-level reduction (74%), which Nesta attributes partly to participants who already had solar panels and batteries1. Households without that equipment may see a different pattern, though the trial does not report a separate figure for them.
The wider context is that decarbonising domestic heating is critical if the UK is to reach net zero by 2050, and the Government's plan to decarbonise heat is based on installing 600,000 heat pumps per year by 2028, rising to as many as 1.9 million per year from 20351. Nesta states that lowering demand for electricity at peak times can help reduce pressures on the electricity grid, bringing system costs down for everyone and reducing the cost of upgrading and reinforcing the grid1. For a household considering heat pumps and energy independence, the trial addresses one practical question: whether a home can shift its heating load to cheaper periods without losing warmth. The reported temperature and satisfaction data bear on that, but the trial covered 43 volunteer homeowners over a three-month period, and no longer-term performance data is given1.
What happens next
The press release does not set out dated next steps for the trial or for any follow-on work. It reports the trial results and the accompanying Cornwall Insight modelling, and states that remote control automation could be scaled up to reduce the cost of upgrading the electricity grid as more people switch away from fossil fuel heating1. No further trial dates, deployment targets or policy commitments are given in the source.