Nesta, a research and innovation foundation, published the findings of the discovery phase of its boiler flow temperature project on 21 April 2022. The work examined why householders may be reluctant to change their boiler settings and how advice on the subject might reach a wider audience1.
Nesta states that almost every condensing combi boiler in the UK is not operating to its maximum efficiency, and that boilers are burning more gas, generating more emissions and costing households more than they need to. It reports that if these boilers were optimised, households could reduce their energy use, costs and emissions by 6 to 8 per cent. Applied on a large scale, Nesta says the action could reduce total household emissions across the UK by 1 per cent and total boiler emissions by up to 1.5 per cent1. A large part of boiler optimisation can be achieved by reducing the boiler flow temperature, the temperature at which the boiler provides water to radiators, which Nesta describes as a fairly simple and quick change to make1.
The discovery phase drew on 8 householder interviews and 9 stakeholder interviews with advice agencies, boiler manufacturers and industry bodies1. Nesta reports that many people have limited understanding of how to run their heating efficiently, that householders are often wary of changing boiler settings, particularly as energy costs are rising, and that there is a lack of trustworthy advice on how best to heat homes. Among stakeholders, it found that some advice agencies are hesitant to recommend changing boiler settings without greater evidence of effectiveness, and that engineers are concerned such changes may result in expensive call-outs or complaints from customers1.
"Our team is working on solutions that help people to change their boiler settings to save energy."
Nesta identified two key barriers to optimising boilers: a lack of clear, easy-to-use instructions applicable to the wide range of different boiler controls, and a need for definitive proof that changing boiler settings reduces energy use and bills1.
Why it matters for households
A condensing combi boiler only reaches its rated efficiency when it runs in condensing mode, which depends on the temperature of the water returning to it from the radiators. Lowering the flow temperature is the lever Nesta identifies for bringing more boilers into that mode, and the reported 6 to 8 per cent saving applies to energy use, costs and emissions together1. For a household, that is a reduction in gas consumed for the same heating, which bears directly on how much of its energy supply a home pays for and how exposed it is to price movements. The same change reduces the carbon dioxide produced by the boiler, so a home cutting its gas use also cuts its emissions without replacing any equipment1.
The findings also set out why the change is not being made at scale. Nesta reports that householders lack confidence in altering settings, that advice is fragmented and that some advisers want stronger evidence before promoting it1. The practical consequence is that the size of the saving depends less on the boiler than on whether a household can find instructions matching its own controls and can tell whether the change has worked1.
What happens next
Nesta says that, based on the discovery phase findings, it has decided to develop a set of clear instructions to help consumers change their boiler settings, and to gather evidence on the impact of changing boiler settings on consumers' energy consumption and bills1. No dates for either step are given in the update.