Nesta's research summary

Nesta has sought to create a robust and detailed evidence base on lowering flow temperatures as an energy-saving measure.

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Overview

Nesta has commissioned or undertaken a number of streams of work, they include:
  • Reviewing existing evidence on the impact of reducing flow temperatures. This work was carried out by Salford University.
  • Measuring the impact of lowering flow temperatures in the Energy House at Salford University. The Energy House is a testing lab, including a traditional early twentieth century two bedroom terraced house, set up in an environmental chamber.
  • Estimating the proportion of UK homes that could successfully lower flow temperatures, based on modelling work by Cambridge Architectural Research.
  • Modelling the savings and impact on room temperatures as a result of changing flow temperatures, in a range of different housing types with occupants and heating preferences. This work was carried out by Energy Systems Catapult.
  • Running a trial to test the effectiveness of our online tool for lowering flow temperatures with customers of the energy saving app Loop. This work was carried out by Nesta and the Behavioural Insights Team, in partnership with Loop.
All these reports can be found on Nesta’s website. There is still room to learn more, and we are continuing to do further research
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Key takeaways

  • 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.
  • 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.

Nesta has created a simple online tool to help people change their settings, based on extensive user research and testing. Our evaluation clearly shows that users are able to change their boiler settings and feel confident that they’ve done so correctly. Our research has included:

  • Early user testing with 46 participants from Nesta and Carbon Co-op, which informed the development of a prototype online tool. Testing usability and comprehension with 165 participants that were broadly representative of the UK population.  Qualitative and quantitative data from this process helped us to further improve the tool. Seventy-seven percent of research participants said they would lower their boiler flow temperature based on the guidance.
  • Field testing via a pilot randomised controlled trial where the tool was sent via email to 3,500 users of Loop, an energy saving advice app. Thirty-four percent of those who received the tool reported lowering their flow temperature two weeks later, compared to 19% in a control group. This was a statistically significant difference, and suggests that the tool is effective in helping people to reduce their flow temperatures. Participants who used the tool rated the instructions 4.8 out of 5 for ease and 4.3 out of 5 for how confident they felt that they’d changed the settings correctly.
  • Gathering ongoing feedback on the beta tool hosted on the Nesta website. Based on over 2,000 responses from people who have used the tool, we found that people rated ease and confidence 4.8 and 4.3 out of 5. They also rated the likelihood of sharing the tool with their friends and family 4.6 out of 5.

Given the testing we’ve done, and feedback we’ve received, we’re confident that the majority of digitally literate households will be able to successfully change their boiler settings with our online tool.

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