In October 2022, Nesta launched the Money Saving Boiler Challenge. This campaign aims to help over one million households change their combi boiler settings to save energy over the winter. Find out more at www.moneysavingboilerchallenge.com.

The campaign helps households save money by lowering the flow temperature on their condensing combi boilers to 60°C. Our evidence suggests that households could save about 9% on their total gas bill by doing this, assuming their flow temperature is currently set at 80°C.

For a medium-sized household with an annual gas consumption of 12,000 kWh, this would save 1,092 kWh of gas per year which in the winter of 22/23 equated to a saving of £112 annually.

Nesta has sought to create a robust and detailed evidence base on lowering flow temperatures as an energy-saving measure. The work we have done and commissioned so far includes:

• Reviewing existing evidence on the impact of reducing flow temperatures. This work was carried out by Salford University.
• Measuring the impact of lowering flow temperatures in the Energy House at Salford University. The Energy House is a testing lab, including a traditional early 20th-century, two-bedroom terraced house, set up in an environmental chamber.
• Estimating the proportion of UK homes that could successfully lower flow temperatures, based on modelling work by Cambridge Architectural Research.
• Modelling the savings and impact on room temperatures as a result of changing flow temperatures, in a range of different housing types with occupants and heating preferences. This work was carried out by Energy Systems Catapult.
• Running a trial to test the effectiveness of our online tool for lowering flow temperatures with customers of the energy saving app Loop. This work was carried out by Nesta and the Behavioural Insights Team, in partnership with Loop.

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