About Nesta

Nesta is an innovation foundation. For us, innovation means turning bold ideas into reality and changing lives for the better. We use our expertise, skills and funding in areas where there are big challenges facing society.

Investigating the link between boiler flow temperature and emissions

Almost every condensing combi boiler in the UK is not operating to its maximum efficiency. Boilers are burning more gas, generating more emissions and costing households more than they need to. If these boilers were optimised, households could reduce their energy use, costs and emissions by 6-8%. If applied on a large scale, this action could reduce total household emissions across the UK by 1% and total boiler emissions by up to 1.5%.

A large part of boiler optimisation can be achieved by reducing the boiler flow temperature, that is, the temperature at which the boiler provides water to radiators. This is a fairly simple and quick change to make. Our overall aim is for as many homes as possible to feel confident enough to act on this advice.

Our team is working on solutions that help people to change their boiler settings to save energy.

This update explains what we have done in the discovery phase of the project, which includes findings from:

  • 8 householder interviews
  • 9 stakeholder interviews with advice agencies, boiler manufacturers and industry bodies

Based on the discovery phase findings, we have decided to:

  • develop a set of clear instructions to help consumers change their boiler settings
  • gather evidence on the impact of changing boiler settings on consumers energy consumption and bills

What did we do?

We spoke to eight households to understand why they may be hesitant to change their boiler settings. We also spoke to stakeholders to understand what heating industry experts think about the idea and to understand how consumer advice organisations might communicate our advice to a wider audience.

Our household interviews explored how people use their home heating. These interviews highlighted that:

  • many people have limited understanding of how to run their heating efficiently
  • householders are often wary of changing settings on their boilers – particularly as energy costs are rising
  • although some homes had technology that could manage heat demand for users, heating is often still managed manually
  • there is a lack of trustworthy advice on how to best heat homes and people don’t know where to turn for help.

We also spoke to relevant stakeholders, including energy providers, consumer advisory groups and heating specialists. These interviews highlighted that:

  • some advice agencies are hesitant to recommend changing boiler settings in the absence of greater evidence of effectiveness
  • engineers are concerned that changing boiler settings may result in expensive call-outs or complaints from customers.

We drew on this research to develop a set of personas that capture the varying viewpoints of the households we spoke to and the varying stakeholders that exert influence over this area.

We also developed a user journey map that shows the steps that someone would take to change their boiler settings. This map runs from initially becoming aware of the advice to actually making the change and finally to sustaining the change over time.

This map also outlined the key actions that stakeholders need to take to support households in discovering, making and sustaining a change to their boiler settings. For example, they could highlight the low risk and reversibility of the change to build user confidence, or offer bespoke advice to help households with actioning the advice.

You can see our full user journey map below.

The discovery phase of this project uncovered two key barriers to optimising boilers. Firstly, there’s a lack of a clear and easy-to-use set of instructions that are applicable to the wide range of different boiler controls. This is preventing people from feeling confident enough to change their settings. Secondly, there’s a need for definitive proof that changing boiler settings reduces energy use and bills. This is needed for some organisations to feel confident in promoting this advice to consumers.

Based on the discovery phase findings we have decided to:

  • develop a set of clear instructions to help consumers reduce their boiler’s flow temperature and equip them with the knowledge to change other heating settings within their home
  • gather definitive data on the impact of reducing flow temperatures on consumers energy consumption and bills.


Andy Marsden

Andy Marsden

Andy Marsden

Design Lead, Design & Technology


Andy is the design lead for the sustainable future mission.

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Shaan Jindal

Shaan Jindal

Shaan Jindal

Senior Analyst, sustainable future mission

Shaan is a senior analyst in the sustainable future team.

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