The settings behind the savings
Cambridge Architectural Research compared household energy-saving measures for Nesta in updated modeling published in September 2026. Nesta is promoting the findings as temperatures fall after an unusually warm start to autumn, saying the £57 boiler saving could help offset October's £60 energy price cap increase.
The boiler recommendation is to reduce the flow temperature to 60°C. Nesta says many combi boilers leave the factory set at 75°C or 80°C, temperatures that prevent them from operating efficiently. Its modeling puts the average annual saving from this change at £57.
Two other measures carry larger individual estimates: lowering the home thermostat from 20°C to 19°C could save £67 a year, while limiting the heating season to October through March could save a typical household £65. The latter means switching the heating off before April, when the weather is milder.
For rooms other than the living room, Nesta recommends adjusting thermostatic radiator valves to make those spaces 1.5°C cooler, for example by moving a valve from setting 5 to 3. The estimated annual saving is £41, while the most-used room remains at its existing temperature.
The remaining measures each have an estimated £7 annual saving: disabling a combi boiler's pre-heat function and closing curtains at night. Pre-heat keeps some water warm even when it is not being used; Nesta says turning it off still allows consistently hot water when needed. Curtains help retain heat by forming a barrier at windows, yet around a third of Britons do not close all their curtains overnight, according to Nesta.
The £220 figure is the modeled saving from combining all six adjustments, rather than adding their individual estimates together.
How Nesta calculates the £57 estimate
The Money Saving Boiler Challenge bases its current figures on the Ofgem price cap for October through December 2026. For an average household consuming about 7,400 kWh of gas annually, it estimates that changing the flow temperature from 75°C to 60°C would reduce gas use by roughly 10%.
That represents up to 720 kWh, worth £57 at a gas price of 7.97p per kWh. For a higher-use household consuming 14,000 kWh annually, the campaign estimates a saving of about £82 a year.
Nesta-funded tests at the University of Salford's Energy House also examined the setting change. On a typical UK winter day, lowering the flow temperature from 80°C to 60°C saved 7% in gas use; lowering it from 70°C to 60°C saved 12%. Going below 60°C brought only marginal additional efficiency gains and made rooms take substantially longer to heat.
What earlier modeling and a field trial found
Nesta's original 2022 modeling, also conducted by Cambridge Architectural Research, estimated that 38% of UK homes could benefit from a 60°C flow temperature. It put potential UK energy-cost savings at about £1 billion annually.
Under that earlier model, a typical household could save £97 a year, or 8% of its gas bill, if occupants accepted slightly lower room temperatures. With indoor temperatures unchanged, the estimated saving from efficiency improvements alone was £43 a year.
A separate randomized controlled field trial tested how households responded to advice. Nesta studied 61,000 users of the Loop smart-meter app between January and April 2023. One group received month-specific recommendations: 60°C for January and February, 55°C for March and 50°C for April.
That group used about 0.4% less gas per day than the control group, a small but statistically significant difference. A one-time email recommending 60°C did not produce a statistically significant change. The trial also found no significant differences in reported thermal discomfort or daily electricity consumption.
Campaign results and the next target
Nesta estimates that its Money Saving Boiler Challenge has prompted about 3.1 million households to lower their boiler flow temperatures. It attributes nearly £300 million in household savings and an estimated reduction of 500,000 metric tons of CO2 to the campaign, along with £157 million saved by HM Treasury through lower spending on the Energy Price Guarantee.
Energy companies and heating advisers are supporting the campaign. Rebecca Dibb-Simkin, chief customer officer at Octopus Energy, said: "Just five minutes tweaking your boiler settings could save you £57 a year."
Linsey McGarrigle, chief operating officer at British Gas, said changes such as lowering a combi boiler's flow temperature "can make a real difference without affecting comfort". Jo Alsop, co-founder of The Heating Hub/Warmer Academy, described lowering the flow temperature on a suitable boiler as a practical way to save without sacrificing comfort.
Nesta says another million households making the boiler adjustment could collectively save £57 million. If those households adopted all six measures, it estimates their combined energy-cost savings could reach £220 million by April.
