• Changing settings on combination boilers in the UK can save 10 million households an average of £112 a year each - cutting a total of £1 billion from energy bills and saving £500 million for the Treasury
• Nesta launching campaign in partnership with Which?, Energy UK, EDF, E.ON Next and Octopus Energy with online tool to provide DIY step by step guidance
• Nesta calculates that combining five free energy saving measures would save £3 billion for households on bills and £1.5 billion for Government

Changing a single setting to make your combination boiler work more efficiently can save around £112 a year in energy bills for a typical household, making it one of the most effective free energy saving measures, according to new research published today by the innovation charity Nesta.

Nesta is launching a new simple step-by-step online tool to help guide people through quickly and easily turning down their combi boiler flow temperature. The tool is supported by campaign partners Which?, Energy UK, EDF, E.ON Next and Octopus Energy.

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 and save 1.7 million tonnes of carbon emissions, the equivalent of almost 6 million transatlantic flights. Nesta also estimates that due to the Energy Price Guarantee, this would save HM Treasury £500 million.

Many people don’t know they can save money by reducing their boiler’s flow temperature. According to ONS data, only 1 in 10 people had lowered their flow temperature in the last year, compared to 6 in 10 who had lowered their thermostat.

To see how lowering boiler flow temperature compared to other actions people can take to reduce their energy bills, Nesta commissioned Cambridge Architectural Research to compare various energy saving measures. The research found that reducing a combination boiler’s flow temperature saved more money than fitting a smart thermostat - which saves a typical household £64 per year - as well as better known free measures, such as closing curtains at night (saving £10 per year) and placing foil behind the back of radiators (saving £3-11 per year).

Madeleine Gabriel, Director of Sustainable Future at Nesta, said:

“While the Energy Price Guarantee is helping millions to avoid financial ruin from high energy bills, the actual amount people pay still depends on their energy use, so it is important that anyone needing to keep costs as low as possible this winter feels confident taking action. Many people are already doing as much as they can to save money on energy bills but there are hidden tricks that people can take themselves that don’t affect their comfort.

“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. To help as many people as possible save money and reduce carbon emissions, we have designed a tool to guide anyone through this step by step.”

The temperature that a boiler heats water up to before it circulates around the radiators in a home is called the flow temperature. Combination boilers work most efficiently if the flow temperature is set to 60°C or below, but boilers are often set much higher than that. Changing the flow temperature is different to changing the temperature on a thermostat, which saves energy just by lowering overall room temperatures. Reducing flow temperatures to 60°C saves energy by helping boilers run more efficiently and heating rooms a bit more slowly, with only a slight reduction in overall temperature for some homes with poorer insulation.

Nesta commissioned Salford University to test how much gas is saved by lowering flow temperatures in a real-world environment. These show that reducing flow temperature from 80°C to 60°C can save 9% of total gas use, or £112 for an average home. Tests revealed that while lowering the boiler flow temperature means it takes a little longer (up to 15 minutes) for the home to reach the right temperature, this still saves more money and energy than having a higher flow temperature and putting the heating on for a shorter period.

Due to the rising price of gas and electricity, the UK Government has brought in the Energy Price Guarantee, which means that the maximum unit price households can be charged for electricity is 34p per kWh of electricity and 10.3p per kWh of gas. This means that the annual energy bill for a typical household will rise to £2,500. However, the amount each household actually pays depends on the amount of energy they use, so many people can benefit by making their home as energy efficient as possible.

Most people are already planning on taking some steps to energy money on their energy bills this winter. Two thirds of people (67%) polled by the Behavioural Insights Team for Nesta said they would wear warm clothes instead of turning on the heating in their homes this winter, more than half (57%) said they would keep the heating on for fewer hours and 46% said they would lower the thermostat. More than half (51%) also said they would close curtains while 12% said they would put foil or reflectors behind radiators.

Rocio Concha, Which? Director of Policy and Advocacy, said:

“Energy bills have spiralled during the cost of living crisis, so people are looking for simple steps they can take to save money. We are supportive of Nesta's new tool, which shows how reducing the flow temperature on combi boilers can help consumers shave money off their heating bills, without compromising on the temperature they heat their home to.

"We are also calling on the government to turbo boost the insulation of homes to help consumers save energy and reduce their bills. It is also vital that energy companies do all they can to support their customers through this extraordinary cost of living crisis."

Nesta’s research shows that combining energy saving measures can save households even more money. If a household with average gas consumption lowers their combination boiler flow temperature to 60°C, reduces the temperature of their hot water, and adjusts thermostatic radiator valves in some rooms, they could save around £180 on annual energy bills. Nesta calculates that five free energy saving measures could save £3 billion on household bills and £1.5 billion for Government, if adopted by all eligible homes.

Topping up loft insulation or adding a smart meter as well could bring savings up to £230. Millions of households could make these types of changes, and Nesta estimates that supporting them to do so could reduce total household energy demand by 20% over a year.

The online tool to reduce boiler flow temperature can be found at: www.moneysavingboilerchallenge.com

Ends

Notes to editors

1. Nesta has launched the Money Saving Boiler Campaign, in partnership with Which?, Energy UK, EDF, E.ON Next and Octopus Energy, featuring an evidence-based online tool to guide people step by step through reducing their combination boiler flow temperature. A summary of the evidence used in the campaign is available on Nesta’s website.
2. Nesta commissioned the Salford Energy House to test how gas consumption for heating varies at flow temperatures of 80°C, 70°C, 60°C, 55°C and 50°C. The tests were carried out between August and September 2022. The Salford Energy House is a traditionally built, two-bedroom terraced house with solid brick walls, suspended timber floors and single-glazed windows with a conventional “wet” central heating system fired by a gas boiler. It has an energy efficiency rating of D. The Energy House is built within an environmental chamber that can simulate different temperatures and weather conditions. The tests were conducted with outdoor temperatures of 4.5°C, to simulate average UK winter temperatures. Most condensing boilers in use across the UK are set with flow temperatures of 70-80°C, with CAR estimating that 90% of combination boilers are set to 75°C or similar. The Salford Energy House evidence suggests that homes that currently have their boiler flow temperatures set to 80°C could reduce gas consumption for space heating by 12% by setting their flow temperature to 60°C, or by 16% by turning down to 55°C. Assuming that homes use approximately 75% of their gas on space heating, this means that these reductions in gas demand would result in overall gas consumption savings of 9% (for those turning down to 60°C) or 12% (for those turning down to 55°C). Based on the 9% saving on total gas use from reducing flow temperatures from 80°C to 60°C (reported above), we estimate that a medium-sized household with an annual gas consumption of 12,000 kWh would save 1,092 kWh of gas per year. At a price of 10.3p per kWh of gas (the Energy Price Guarantee unit rate for gas), this equates to £112 per year.
3. Nesta commissioned Cambridge Architectural Research (CAR) to model the savings that can be made through lesser known, free or low cost measures. This work was supported by an academic literature review by the Energy House Labs Team at the University of Salford. Nesta has summarised these findings and published the full table of CAR’s findings on its website. These estimates have been 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 are estimated using the best-available evidence from field trials and lab tests, supplemented by modelling and explicit assumptions. CAR modelled the saving for reducing the flow temperature of combination boilers from 75°C to 60°C and found this would be between £63 and £106, with an average of £97.
4. CAR estimated the proportion of homes that could potentially benefit from turning down combi boiler flow temperature to 60°C. Their ‘most likely’ estimate is 38% of all homes, or 10.7 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. The public opinions and social trends survey of 4,974 households between 22 June to 3 July 2022, by the Office of National Statistics, found that 1 in 10 people have lowered their boiler flow temperature in the last 12 months compared to 6 in 10 who have lowered their thermostat.
6. Nesta commissioned the Behavioural Insights Team to survey a sample of 4,009 UK adults between 19 and 30 August 2022.
7. Wholesale gas costs will be 13p-16p per kWh in 2023 (£360-£474 per therm), according to Intercontinental Exchange, Inc. (a company that operates global financial exchanges and provides mortgage technology, data and listing services). Under the Energy Price Guarantee, households pay 10.3p per kWh for gas meaning that HM Treasury will pay approximately 5p per kWh of gas. Nesta has calculated the £1bn annual savings for consumers from lowering their boiler flow temperature (940 kWh of gas reduction per household, among 10.7m eligible households) would provide HM Treasury with £500m in annual savings.
8. Nesta estimates that five free energy saving measures could cut a total of £3 billion from home energy bills and save HM Treasury an additional £1.5 billion, if adopted by all homes that could benefit from them. The five free measures are: 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, and readjusting existing TRVs outside the living room to 1.5°C cooler than before.

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.

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