Nesta launched the Money Saving Boiler Challenge in October 2022, in partnership with Which?, Energy UK, EDF, E.ON Next and Octopus Energy1. The campaign centres on a step-by-step online tool that guides households through reducing the flow temperature on a condensing combi boiler to 60°C1. Nesta published supporting evidence for the campaign on 10 October 20222.
Nesta's research, published on 13 October 2022, states that reducing flow temperature from 80°C to 60°C can save 9% of total gas use, or £112 a year for an average home1. The figure is based on a medium-sized household using 12,000 kWh of gas a year, saving 1,092 kWh, priced at the Energy Price Guarantee unit rate of 10.3p per kWh of gas1. Nesta commissioned the Salford Energy House to test gas consumption at flow temperatures of 80°C, 70°C, 60°C, 55°C and 50°C between August and September 2022, at an outdoor temperature of 4.5°C1. Nesta also estimates that if 10 million UK households with combi boilers reset their flow temperature to 60°C or below, this would cut £1 billion from energy bills, save 1.7 million tonnes of carbon emissions and save HM Treasury £500 million under the Energy Price Guarantee1.
Nesta calculates that five free energy saving measures, adopted by all eligible homes, could reduce household gas use by 10%, saving £3 billion for households over a year and £1.5 billion for Government3. The five measures are listed as:
| Measure |
|---|
| Reducing flow temperature to 60°C for combination boilers |
| Reducing the cylinder temperature to 60°C for system boilers |
| Turning off pre-heat facilities on combination boilers |
| Reducing hot water temperature to 42°C in homes with combination boilers |
| Readjusting existing thermostatic radiator valves outside the living room to 1.5°C cooler than before |
Source: Nesta3
Nesta adds that rolling out additional low-cost measures under £300 each, including topping up loft insulation, installing smart thermostats and installing TRVs where these are not already present, could bring total savings up to £7 billion3. Nesta's research found that less than half of the general public are unaware that it is possible to change the flow temperature on a boiler3; a separate Nesta release states that more than half of the general public are unaware of this4. According to ONS data cited by Nesta, only 1 in 10 people had lowered their flow temperature in the last year, compared to 6 in 10 who had lowered their thermostat4.
"We have found people can save £112 a year just by making one change to their combination boiler to make it more efficient - a much bigger saving than many better-known energy saving tips."
Why it matters for households
The campaign addresses a setting most households have never adjusted. Nesta's evidence is that combi boilers run most efficiently at a flow temperature of 60°C or below, but that most condensing boilers in use across the UK are set at 70-80°C, with Cambridge Architectural Research estimating that 90% of combination boilers are set to 75°C or similar1. Lowering the flow temperature is distinct from lowering a room thermostat: it saves energy by helping the boiler run more efficiently rather than by reducing overall room temperature, though Nesta's tests found it takes up to 15 minutes longer for a home to reach the right temperature1. For a household, the practical effect is a reduction in gas consumed for space heating without a deliberate cut in comfort, which matters for energy independence because it lowers the volume of gas a home must buy rather than the price it pays. Nesta's comparison found the flow temperature change saved more than fitting a smart thermostat, which it puts at £64 a year for a typical household, and more than closing curtains at night (£10 a year) or placing foil behind radiators (£3 to £11 a year)1. Nesta's modelling covers boilers and heating generally; the campaign tool applies specifically to combi boilers, and Nesta notes that not all homes have one, and that some homes' radiators and pipework may not suit a 60°C flow temperature5.
What happens next
Nesta called on the Government to launch an energy saving campaign as part of its review of the Energy Price Guarantee, saying a campaign is "the missing plank of a responsible long-term plan for energy bill support"3. On 25 October 2022 the Government included the Money Saving Boiler Challenge tool in new energy saving tips for households, published as part of its "Help for Households" advice on Gov.uk4. Nesta said more than 70,000 people had used the tool by that date4. No further dated steps are set out in the sources.
Sources5 cited
- UK households could save £1 billion on energy costs by making one simple change | Nesta, nesta.org.uk
- Money Saving Boiler Challenge: supporting evidence October 2022 | Nesta, nesta.org.uk
- Government energy saving advice campaign is missing plank of long-term plan for energy bill support | Nesta, nesta.org.uk
- Government energy saving advice features Money Saving Boiler Challenge that can save households around £112 a year | Nesta, nesta.org.uk
- Wallet Warmers: British families can save £160 on annual bills through free and easy energy saving tweaks | Nesta, nesta.org.uk