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  • Three free, “set and forget” actions can cut £160 from the annual energy bill
  • Turning down boiler flow temperature is one of the biggest savings, yet nearly 1 in 3 eligible households still haven't made this simple tweak to their home heating
  • Nesta’s Money Saving Boiler Challenge online tool can help with turning down boiler flow temperature and could save households a total of around £520m on energy bills

Families around the country looking to save money this winter could save £160 on their annual energy bill by making free tweaks to their home heating, according to new research published today by the charity Nesta.

Many people in the UK are struggling to make ends meet due to the high cost of living and will again be looking for ways to reduce their bills. As colder months roll in, energy bills are likely to remain historically high, despite reductions from last year when the UK Government put the Energy Price Guarantee in place. Nesta’s research shows that by combining a few free and hassle-free actions, people can make their savings add up while keeping their homes warm.

Cutting costs

The research by Cambridge Architectural Research (CAR), commissioned by Nesta, finds that with three key no-cost tweaks families can make savings on their annual energy bills of:

  • £65 on average by turning down their combi boiler flow temperature to 60°C;
  • £17 by setting the hot water temperature on a combi boiler to 42°C;
  • an additional £78 by turning down the radiator valves outside the living room by one setting.

Many people will be able to “set and forget” these free tweaks and still save money, with no noticeable difference to the overall temperature of their homes.

Boiler flow bliss

Nesta's Money Saving Boiler Challenge campaign aims to support households to turn down their boiler flow temperature, and offers a simple step-by-step online tool to help people to do it quickly and easily. The campaign, which is run in partnership with Which?, Energy UK, EDF, E.ON Next, Octopus Energy and Heating Hub, features in the Government’s Help for Households official advice, as well as on the Money Saving Expert website and ITV’s the Martin Lewis Money Show.

The campaign went live in October 2022. Nesta’s research suggests that from launch to March 2023, 3.1 million households turned down their boiler flow temperatures. We estimate that this saved around 500,000 tonnes of CO2 and generated nearly £300m in bill savings for households.

There are many more households who have yet to make this simple tweak to their home heating. While not all homes have combi boilers, and some have already adjusted their flow temperatures, CAR estimates that around 29% of all UK homes could still benefit from doing so. This could save households a total of around £520m on energy bills, while cutting an additional 1.4m tonnes of CO2.

Katy King, deputy director of sustainable future at Nesta, said:

“This winter will be a cash flow crunch point for many families and energy bills remain a sore point. In a cost of living crisis where every penny counts, we want to help UK households stay warm while giving the cold shoulder to higher bills.

“Our research has found that with just three free and simple one-off tweaks around the home, people can save £160 on their annual bill. Reducing boiler flow temperature to 60 degrees and setting hot water temperature at 42 degrees on a combi boiler, as well as turning down radiator valves, together should lower costs while maintaining comfort. In addition to warming people’s wallets with some extra cash, these actions also come with a green benefit by reducing the carbon used for home heating.”

Hidden heating savings

Though energy costs have gone down since last year, Ofgem’s energy price cap is set at £1,923 a year for a typical direct debit household from October, with costs determined by how much gas and electricity each household uses.

Previous research from the Behavioural Insights Team, owned by Nesta, has shown that many people don’t realise that their energy bill will vary depending on how much they use. When asked about the Energy Price Guarantee, which is in place as a safety net should the Ofgem price cap go over £3,000 a year, 4 in 10 (41%) who knew about it incorrectly believed that the cap was a maximum threshold regardless of usage, when it is actually a cap on the amount that a typical household would pay.

Nesta’s free online tool guides people through reducing boiler flow temperature step-by-step, so that anyone can do it, and this takes just a few minutes – it can be found at: moneysavingboilerchallenge.com


Notes to editors

  1. For more information on the analysis or to speak to one of the experts involved, please contact Kieran Lowe, Media Manager, on 020 7438 2576 or [email protected]. Spokespeople are available for broadcast interviews.
  2. In August 2023, Nesta commissioned Cambridge Architectural Research (CAR) to update its modelling of the savings that can be made through free or low cost measures using gas and electricity prices consistent with Ofgem’s October 2023 price cap. The modelling was initially undertaken in 2022, supported by an academic literature review by the Energy House Labs Team at the University of Salford. The estimates were generated using the Cambridge Housing Model, a bottom-up model developed by CAR that estimates energy consumption in the 12,300 dwellings surveyed in the English Housing Survey and the CODE (“Cost Effective Domestic Electrification”) model, which contains 12 archetypes of typical homes derived from English Housing Survey (EHS) data, with weights derived from the EHS. Per-dwelling energy savings were estimated using the best-available evidence from field trials and lab tests, supplemented by modelling and explicit assumptions. Nesta has published the full table of CAR’s findings on its website.
  3. The estimated savings from adjusting boiler flow temperature on a combi boiler are based on turning down from 75°C to 60°C. Savings from adjusting the hot water temperature on a combi boiler are based on turning down from 52°C to 42°C. Savings from adjusting thermostatic radiator valves (TRVs) assume that all TRVs outside the living room were previously fully open (i.e., set to the highest setting). TRVs vary in terms of the number of settings they have – most have five or six. One setting change roughly corresponds with a temperature difference of 3-5°C. Potential savings from turning down boiler flow temperature and radiator valves together slightly lowers the possible individual savings of each. Combined with setting hot water temperature to 42°C this equates to £160 annual savings in total.
  4. CAR estimated the proportion of homes that could potentially benefit from turning down combi boiler flow temperature to 60°C, adjusting this in their 2023 update to take account of the proportion of homes that may already have done this. Their ‘most likely’ estimate is 29% of all homes, or 8.1 million homes. This takes into account the proportion of homes that have combi boilers, the likelihood that they currently have flow temperatures of 75°C or higher and the suitability of their current radiators and pipework to heat homes effectively with flow temperatures of 60°C.
  5. CAR’s updated estimate of homes able to benefit from adjusting combi boiler flow temperatures was informed by campaign tracking commissioned by Nesta. To find out how many people had turned down their boiler flow temperature before and after the launch of the Money Saving Boiler Challenge campaign, Nesta commissioned Walnut Unlimited to carry out 5 minute online surveys among a sample of 2,008 and 2,007 adults in Great Britain between 7–9 October 2022 and 22-24 March 2023. Data was weighted by age, gender, social grade and region.
  6. In early October 2022, 21% of people said they had lowered their boiler flow temperature in the past. This rose to 32% when the survey was repeated in March 2023. We estimate this equates to approximately ~3.1m households turning down their boiler flow temperatures over the course of the campaign – saving an estimated 500,000 tonnes in CO2 and nearly £300m in savings for households and £157m for HM Treasury (in reduced spending on the Energy Price Guarantee). These savings are based on the assumptions that each boiler turned down saved a household £96 a year (inc VAT).
  7. From October 2023, Ofgem is updating its assumptions on ‘typical’ gas and electricity usage (‘Typical Domestic Consumption Values’ or TDCVs). The TDCV for electricity is reducing from 2,900 to 2,700 kWh per year, while the TDCV for gas is reducing from 12,000 to 11,500 kWh per year. The price cap figure of £1923 is based on the old TDCVs. Ofgem will update this in October 2023 to take the new TDCVs into account: the price cap for this level of usage will be £1834. This does not change the cost of electricity or gas under the October price cap – households will still pay the same unit prices for what they use. The TDCVs have been adjusted to reflect long term downward trends in energy consumption per household.
  8. The Behavioural Insights Team, part of Nesta since 2021, ran an online experiment on the energy crisis with a sample of 2,022 UK adults collected between 4th to 17th November 2022.

About Nesta

We are Nesta, the UK's innovation agency for social good. We design, test and scale solutions to society's biggest problems. Our three missions are to give every child a fair start, help people live healthy lives, and create a sustainable future where the economy works for both people and the planet.

For over 20 years, we have worked to support, encourage and inspire innovation. We work in three roles: as an innovation partner working with frontline organisations to design and test new solutions, as a venture builder supporting new and early stage businesses, and as a system shaper creating the conditions for innovation.

Harnessing the rigour of science and the creativity of design, we work relentlessly to change millions of lives for the better. Find out more at nesta.org.uk