The majority of gas boilers in the UK aren’t running as efficiently as they should. They’re burning more gas, creating more emissions and costing households more money than they need to. Our project is investigating how to encourage and support households to increase the efficiency of their existing gas boilers by lowering their flow temperature – the temperature at which the boiler sends water to the radiators. This could reduce household energy use by 6-8%.

This phase focused on developing a deeper understanding of the barriers households may face in lowering their flow temperature, as well as the most effective messaging to communicate the change, through an online experiment.

We ran an online experiment with the Behavioural Insights Team (BIT) to:

• determine which messaging is most effective at encouraging research participants to change their boiler settings
• confirm whether common concerns identified in previous phases of the project were applicable to a larger population/sample
• identify any new/further barriers households may face in changing their boiler settings.

A sample of 959 participants, representative of the UK's population in terms of gender, age, ethnicity and region of residence, were recruited from the Behavioural Insight Team's participant base. These participants were randomly assigned to see information about how lowering boiler flow temperatures could reduce energy use with a selection of messages:

• you could save hundreds of pounds each year by changing your boiler settings
• you could be losing hundreds of pounds each year by not changing your boiler settings
• small changes can make a big difference to your energy consumption.

There was also a control group that didn’t see any information other than how lowering boiler flow temperatures could reduce energy use. Participants were then asked whether they would consider changing their boiler settings and why they might be hesitant to do so.

Our online experiment found that people were very open to lowering their flow temperature. Not only did 92% of participants who saw the “save money” messaging say that they would do so, but 82% of participants in the control conditions said they would too.

Despite these positive indications, some important barriers were highlighted by participants, who said they were:

• worried about making a mistake
• concerned it would make their home colder
• confident their boiler was already set correctly
• confused about what changing the flow temperature does
• satisfied with their current settings so didn’t want to risk changing things.

These barriers closely match the issues identified from our household interviews in the previous phase of this project so it’s particularly reassuring to have our initial findings backed up with a much larger sample.

We also found that people were more motivated to change their settings if shown information with a “you can save money” or “you might be losing money” message, compared to those who didn’t receive any information or saw a “small changes can make a big difference” narrative. This is important for communicating advice in the future.

Whilst consumers are keen to change their boiler settings, they don’t know how or what to do and they want certainty about how it will affect their bills. In the next phase of this project Nesta will:

• develop clear step by step instructions to help households reduce their boiler’s flow temperature with confidence
• build the evidence base about which flow temperature to recommend to householders based on housing and occupancy types.