Boiler retirement: Using trigger points to support homeowners to plan for energy upgrades.

Executive summary

Over the coming years, increasing numbers of UK homeowners are expected to change from gas and oil heating systems to electric heating, such as a heat pump. This involves complex and costly decisions for homeowners who have to consider the changes that might be required to install a new heating system, as well as other upgrades such as solar panels and batteries. 

Trigger points identify the times when these changes are more likely to be convenient and cost effective, and homeowners are more likely to be open to considering them. Examples include when an old boiler needs replacing, when a homeowner is planning a home improvement project, and moving home. Providing homeowners with prompts to consider home energy improvements at these times, and information and advice to support their decisions, can help them to make more timely and informed decisions.

This report brings together the findings from a project Which? ran in 2025 and 2026 that included research to understand homeowners’ behaviour around boiler replacements, the messages that are most effective in engaging homeowners, two communications campaigns and discussions with stakeholders.

Lessons for communicating with homeowners

We tested different messages to see which would be most effective at engaging homeowners to plan ahead for replacing their boiler and ran our own communication campaign in Autumn 2025 to see what lessons could be drawn. We then conducted a further communication campaign in the Spring when homeowners often consider home improvements to further test and build on the lessons learnt. Based on these examples we found:

• The right messaging can significantly increase engagement. Our testing of different messages around boiler replacement showed that the optimal set of three messages could deliver 87% engagement.
• The results of our campaign suggest that keeping the imagery simple and related to the topic (i.e showing a boiler or heat pump) and highlighting the benefits of heating upgrades generated higher engagement.
• The response when we included the campaign in our newsletters was very good. This suggests that communications with homeowners that have already expressed an interest in an issue and where the homeowner has an existing relationship with an organisation delivers high engagement.
• Providing a clear action is also important. Our spring campaign linked through to our Home Energy Planning Service that guided consumers through their choices and provided the option of practical advice more tailored to their property and needs.

From campaign led change to systemic change

As well as running communication campaigns, there is an opportunity for governments and businesses to adopt a more systemic approach that uses trigger points to prompt and support homeowners to consider home energy improvements.

Our final chapter includes proposals from across the sector for how this could be done, including using data from the Gas Safe register to identify trigger points, utilising the engagement that companies have with homeowners when servicing their boiler, and proposals to link incentives to trigger points such as home buying to encourage homeowners to consider energy improvements.

Recommendations

Governments, businesses and organisations in the home energy sectors have an opportunity to use trigger points to support consumers in the transition to electrification by providing them with prompts and information at times when energy upgrades may be more convenient and cost effective. Changing to electric heating at that point in time may not be the right option for all households, but having time to consider their options, and access to good quality information and advice, will support them in making an informed choice.

Replacing an older boiler and Spring home improvements are two important trigger points, but they are not the only opportunities to engage homeowners that may be considering home energy improvements. Planning a home improvement project and moving home are other times when homeowners are more likely to consider changes.

• Governments and businesses should develop strategies for how they will use trigger points, through communication campaigns or more systemic changes, to engage and support homeowners so that they are aware of the home energy improvements they could make and have the information and advice to make informed choices.

Trigger point strategies should:

• use data to identify when homeowners may be at a trigger point. This could include information about the age of their heating system, if they are applying for permission to make changes to their home, or if they are moving home. Data can also be used to better understand homeowners behaviour around trigger points. This data may be held by public bodies or businesses.
• create partnerships with the businesses and organisations that engage with consumers at these times so the information and advice is available when and where consumers need it. This could include energy providers for boiler replacements, DIY stores for home improvement projects, or estate agents and surveyors for moving home.
• build on the findings from existing home energy campaigns run by governments, businesses and organisations to develop effective messaging.
• work with organisations that homeowners trust, as homeowners are more likely to engage with advice from these organisations.
• provide easy access to good quality information and advice that is tailored to the property and the householders needs.

1. Introduction

Over the next two decades most homes in the UK are expected to change from gas and oil heating systems to new electrified systems, such as a heat pump. This transition, which is primarily driven by the need to improve energy security and cut carbon emissions will also help to drive down energy bills over time. However these changes involve complex and costly decisions for homeowners [1].

Awareness of electrical heating is currently low. Heat pumps are likely to be the main form of heating in the future however they remain unfamiliar for most people despite the fact they are widely used in commercial buildings and some European countries. Other forms of heating, such as heat networks, will also have an important role. The government’s Warm and Fuzzy campaign seeks to raise awareness of heat pumps. The campaign has been running since 2025 and features real homeowners, portrayed as knitted characters, talking about the benefits of owning a heat pump. However, engaging consumers is challenging; although heating bills are an increasingly important concern, homeowners see their heating system as largely functional and it lacks the emotive appeal of a new car or a new kitchen.

When homeowners do consider how to replace their current heating system it can often be a challenging decision. The average cost of installing an air to water heat pump is £13,000 [2] and the installation can require decisions around the location of equipment, a new hot water cylinder and new radiators. Homeowners may also want to consider solar panels, batteries or a new smart tariff to reduce their energy bill. As technology develops it is increasingly likely that other electrified heating and cooling options will also be available.

These decisions take some time and, if a homeowner does decide to switch to a new system, the installation is likely to take several days to weeks longer than just replacing a boiler, though the industry is working hard to reduce the time it will take.

Despite these challenges the proportion of consumers open to considering a heat pump is growing [3]. However growth is from a small base and the rate of growth is still below the targets for heat pump adoption that the Climate Change Committee has said are necessary for the UK to meet the government’s legally binding target for meeting net zero emissions by 2050. The government has also set its own interim target for heat pump adoption but this was reduced in the Warm Homes Plan which was published earlier this year [4].

Which? wants consumers to be able to make informed decisions about their next heating system. Currently electric heating will not be the best solution for every household, but there may be other improvements that they can make when replacing an old boiler to help their system to run more efficiently or to prepare for changes at a later date.

This report brings together the findings from a project Which? ran in 2025 and 2026 that sought to understand the approaches governments and businesses can take to engage homeowners and support them to make the best decision for their needs.

Chapter 2 explains why homeowners are more likely to consider home energy upgrades at trigger points. Chapter 3 presents the findings from our research to understand homeowners’ behaviour around boiler replacements. Chapter 4 presents the findings from tests we conducted to find the messages that are most effective in engaging homeowners. Chapter 5 describes two communications campaigns we ran and the lessons we learnt. And chapter 6 presents some recommendations for how governments and businesses could take a more systemic approach to using trigger points.

2. Trigger points

Understanding when homeowners are more likely to be open to considering changes to their heating system is an important step towards providing support at a time and a place that meets homeowner's needs.

Trigger points are recognised as times when people are both more likely to be open to considering changes and when it is also more convenient. There are several trigger points in relation to home energy improvements [5]. 

• Replacing an old heating system: The retirement or breakdown of an ageing gas or oil boiler is a crucial trigger point for considering a switch to electric heating, such as a heat pump.
• Moving home: Moving to a new property is often a time when households make upgrades.
• Undertaking large home improvement projects: When a homeowner is already planning major renovations, such as an extension or layout change, it is a natural time to consider energy efficiency. For example, a homeowner might install underfloor heating and extra insulation while building an extension.
• Financial and life milestones: Paying off a mortgage, retiring, or receiving a large lump sum (such as a pension payout) often prompts 'empty nesters' or older homeowners to invest in home improvements that will reduce their future outgoings.
• Seasonal shifts: Colder weather in early Autumn often triggers homeowners to think about their heating systems, while early Spring is traditionally when many start planning wider home renovations.

Homeowners are more likely to find information about home energy improvements useful at these times because it is relevant to what they are feeling, thinking and doing.

• The rarity of the opportunity: These events do not happen often. For instance, gas and oil boilers tend to last for at least ten years and are therefore only replaced very infrequently. Because these windows of opportunity are so infrequent, homeowners want to make the right decision for the future.
• Momentum and tolerance for disruption: During a move or a renovation, homeowners are already prepared for upheaval, disrupted routines, and having contractors and equipment in their home, making the hassle of installing insulation or a new heating system feel less daunting. During events like a house move or a major renovation, households are more likely to approach projects with enthusiasm and an openness to change.
• People view general "renovations" in highly emotional, aspirational terms (e.g., creating a comfortable and attractive space for themselves and their family), whereas "energy upgrades" are viewed as functional, transactional chores or a hassle. Engaging consumers at renovation trigger points allows energy upgrades to piggyback on the excitement and aspiration of general home improvements. 
• Cost-effectiveness: It is often much cheaper and easier to undertake energy efficiency upgrades when other structural work is already taking place. For example, flushing a heating system or changing radiators is much simpler when a new heating system is being installed.
• Access to professional advice: At these points, homeowners are already in direct contact with tradespeople and professionals who can offer timely, expert advice on energy measures, helping to overcome initial knowledge barriers.

Although making energy upgrades at these points can seem intuitive, there is no guarantee that households will do so. These are often busy periods in homeowner’s lives and they may not have the time or inclination to consider making a change to their heating system without an external prompt and support in the form of advice and information.

Boiler replacement and seasonal shifts

Of the trigger points listed above, replacing an old boiler is one of the most significant, as it is both specific to heating and time bound. Based on this we wanted to better understand consumer behaviour around replacing a boiler and the potential to engage homeowners at this time to support their decision making.

We were also interested in seasonal shifts in the Autumn and Spring as these are times when our own website data shows people are seeking advice on these issues and are therefore more likely to be interested in home energy improvements.

3. Which?’s consumer research findings on behaviour and attitudes towards boiler replacement

In order to better understand consumer behaviour around boiler replacement we conducted two surveys. The first survey was with 2,787 UK homeowners in June 2025 that had older boilers (over 8 years old).  We also surveyed 5,463 UK adults during the same period. From this nationally representative group, we identified and surveyed 1,077 homeowners who had replaced or upgraded their heating system in the past two years (since June 2023).  

Our research with homeowners that had older boilers revealed:

Our research with homeowners that had recently updated their heating system revealed:

• Homeowners surveyed who didn't plan ahead were about twice as likely to face an emergency replacement (39%) compared to those who had planned (19%).
• Homeowners who made an emergency purchase faced more disruption and longer waits.
  • Many homeowners couldn't act quickly enough, restricting options and causing frustration.
  • Emergencies caused discomfort, disrupted routines, and increased stress and anxiety
  • Planning ahead leads to smoother upgrades and time to get the right heating system for the home

• Homeowners that plan ahead for a boiler replacement are also significantly more likely to consider installing an alternative electrified system such as a heat pump. The proportion that considered a heat pump increases significantly if they see information about heat pumps as part of their research.

In summary our research shows that many homeowners do not plan ahead for replacing their boiler. As a result, this can lead to unexpected costs, inconvenience and disruption. In most circumstances this is frustrating, but manageable, however we found the disruption may be more serious for households without savings, older households or households with young children. 

Positively homeowners that do plan ahead are less likely to have those negative experiences. Planning ahead also means they are more likely to consider alternatives to a gas or oil boiler and, if they see information about heat pumps as part of the research, they are significantly more likely to consider purchasing one. 

An interesting finding was that homeowners that plan ahead tend to pay more for their replacement. Installers we spoke to suggest that this may be because they are including measures such as cleaning the system or adding heating controls that may save them money in the long run.

Based on these findings, we wanted to explore the potential for engaging homeowners with older boilers and test how targeted information and messaging could help them avoid the inconvenience of a rushed purchase and prompt earlier consideration of their next heating system.

4. Research to test the most effective messaging to engage homeowners with older boilers

In order to identify messages that would be most effective in encouraging homeowners to plan ahead for the replacement of their boiler, we used two techniques to test and rank 8 different message themes. This allowed us to identify the optimal combination of messages that would engage with the widest possible number of homeowners.

The message themes that we tested

We tested the messages using the Max Diff technique that repeatedly asks respondents to identify the best and worst options from a subset of the messages. This provides a clearer hierarchy than a simple ranking.  Based on this technique the most effective messages in engaging homeowners were found to be those that highlighted financial support and the ability to plan ahead to avoid disruption.

Ranked message themes using MaxDiff (share of preference out of 100)

We then used the TURF technique, which is a statistical analysis of survey preferences to identify the combination of messages that had maximum reach. The most effective combination was found to be the offer of financial support, planning ahead to avoid disruption and the availability of help and advice.

Messaging combinations that achieved the highest reach

[6]

While the two core messages about financial support and planning ahead to avoid disruption were consistent with all groups, the third message varied by audience. The offer of help and advice appealed to most homeowners, while older adults preferred messages that emphasised the convenience of planning ahead, young families preferred messages that emphasised the benefits of not rushing decisions, and those undecided about a heat pump preferred messages that emphasised the ability to choose a more sustainable option by planning ahead.

5. Which?’s communication campaigns on boiler replacements and home energy improvements

Boiler replacement campaign (Autumn)

In order to test the ability of messaging to encourage homeowners to plan ahead for the replacement of their boiler we planned a communications campaign consisting of paid Meta and Reddit static and video ads as well as supportive organic social media posts. The adverts linked through to relevant advice pages on the Which? website. We also highlighted the campaign in our newsletters and obtained some press coverage in trade outlets. 

The campaign ran from late September to mid October in 2025. This period was chosen because homeowners are more likely to be thinking about their heating as it gets colder, but still allowed homeowners to plan ahead if they were concerned their current heating system may not make it through the winter. 

Messaging

The four messages we developed for the campaign were:

The static social media posts used in the Autumn

Home improvements campaign (Spring)

We ran a second campaign in March 2026. Spring is often a time when homeowners plan improvements to their home and this is backed up by the high number of online searches for terms related to home improvements and visits to relevant pages on the Which? website at this time of year. 

The messages used in the Spring campaign covered a broader range of improvements than the Autumn campaign. This reflected the season and an opportunity to consider energy improvements with less urgency than might be experienced in the Autumn when the need to ensure heating is working well creates more pressure. The campaign consisted of paid Meta and Reddit static and video ads. 

Based on the learnings from the Autumn campaign we provided a much clearer action that homeowners could take by providing a single link through to the Which? Home Energy Planning Service which guides homeowners through the options available and gives them an opportunity to enter details about their home to get advice that is more tailored to their home. 

The static social media posts used in the Spring

Learnings from the two campaigns

Due to the project timings and the focus of the second campaign, we weren’t able to take advantage of the message testing described in the previous chapter. However testing messages through surveys and analysis, and testing messages through campaigns provides useful comparisons.

In our campaigns we found that Meta and Reddit worked well together to achieve reach and engagement. Meta provided scale and cost efficiency, making it ideal for driving awareness and clicks, while Reddit delivered contextual depth and engagement quality, positioning it as an effective mid-funnel complement. 

The still adverts  (static assets) consistently outperformed video for driving traffic, suggesting that Which?’s social media audience engages best with quick, benefit-driven messaging that can be absorbed instantly in-feed. However, video played a vital supporting role for awareness and message reinforcement, particularly on Reddit where completion rates were strong.  Engagement was strongest amongst older audiences, with the 65+ age group driving the most landing page views, followed closely by the 55–64 age group and the 45–54 age group. 

• The still adverts (static assets) were the primary driver of engagement on Meta, consistently outperforming video, while video supported incremental reach and awareness.
• Specific executions and leading with benefit-led messaging proved more successful.  In the Autumn campaign the boiler and heat pump image ads encouraged active engagement and drove the majority of clicks. These executions also clearly explained a tangible outcome, such as cost savings or the benefits of planning ahead and this consistently beat softer, emotive themes.
• Targeting homeowners that have already expressed an interest in an issue and providing messages from organisations they trust will produce good results. We saw the greatest impact when the messages were included in the Which? Sustainability and Home heating newsletters. 
• The solar panels advert was very popular in the Spring reflecting what we already knew about the popularity of solar panels compared to other home energy upgrades, but the popularity of these adverts may also have been linked to the season and a March 2026 surge in global energy prices encouraging homeowners to reconsider solar power as a route to self-sufficient electricity generation.
• Providing a clearly defined action. The adverts in the Autumn lacked a prominent and clearly defined action. As a result whilst the adverts delivered good engagement, we didn’t see the onward journeys that we would have expected. In the Spring campaign, we provided a much clearer action. Very good numbers signed up to the Which? Home Energy Planning Service which helps to guide homeowners through the decision making process and creates the opportunity for advice more tailored to their home and circumstances.
• The role of commercial incentives. Discussing the campaign with industry stakeholders identified some challenges around collaboration. Companies in the sector were often supportive of the campaign’s objectives and were well placed to engage homeowners based on their existing relationships. However companies are usually keen to maintain their relationships with customers which can make the introduction of a third party more complicated.

6. Expanding the use of trigger points to engage homeowners

The communication campaigns Which? ran in Autumn 2025 and Spring 2026 illustrate the potential to engage homeowners about home energy upgrades based on trigger points such as boiler replacement and seasonal shifts. 

The timing of the communication campaigns and the messages we used enabled us to highlight issues that homeowners were more likely to be interested in at those times. For example the choice of Autumn as a time when homeowners are more likely to be thinking about their heating and Spring when homeowners are more likely to consider wider home improvements. We were also able to define our social media audiences and engage homeowners that had signed up to our newsletters. 

Building on the idea of using trigger points to engage and support homeowners at times when they were more likely to be considering changes to their heating, we were interested in approaches that would move the concept from a campaign led activity to more systemic change. This could be delivered by making better use of the data that is available. For example one of the proposals below calls for the use of Gas Safe registry data to identify properties with older boilers. Other systemic approaches could involve changing companies practices so that supporting homeowners with prompts and information at trigger points was integrated into their processes.

Proposals for supporting boiler replacements:

Gas Safe registry data

In 2024 Project Ambient, an NGO supporting the transition to net zero, made a proposal for using Gas Safe Registry data to identify properties with older boilers, with the aim of providing these property owners with information and advice on switching to a heat pump.

Since 2005 it has been a legal requirement to register new gas and oil boilers in the UK. Since 2009 the register has been held by Gas Safe. As a result the Gas Safe registry holds data on when the vast majority of boilers were installed. Project Ambient were able to access and analyse some of the data held by the registry (approx 60,000 boilers) and based on this sample they estimated that about 17% of boilers were more than 12 years old.  

However, the data can’t currently be used as homeowners haven’t given their consent to receiving communications from the registry, the Health and Safety Executive (that owns the data) or the government. DESNZ has looked at the potential to use the registry data for this purpose but no further information about whether it could be used is available. 

More information is available from the Project Ambient website [7].

Boiler servicing 

Which? research shows that up to 60% of homeowners have their heating system serviced each year. Whilst this creates an ideal opportunity to encourage homeowners with older boilers to plan ahead for their replacement, it is often noted that the gas engineers who carry out the servicing are more likely to be aware of existing gas technologies and have an incentive for their customers to stick with gas.

One large installer that offers gas boilers and heat pumps has started to trial a new approach that gives homeowners information and quotes for repairs to the current heating system (where this is an option) as well as information and quotes for a new gas boiler and a new heat pump. In time they hope to also include options such as solar panels and batteries. 

If the conflicts of interest can be overcome, this service can help to give homeowners that have their boiler serviced a much clearer idea of their options.  

Proposals for supporting new home owners

Banks talking to their customers about home energy upgrades

Trigger points often involve financing and some banks are training their staff in how to have conversations with their customers about home energy improvements. This could be in the context of a discussion about a loan for other home improvements, or a mortgage for a new home. 

Many banks offer financial products specifically for home energy improvements, but staff needed training to understand how they could raise the issue with customers. Understandably, banks can be wary of giving advice about a topic where they don’t have expertise, however by partnering with other organisations that do have this expertise they are able to signpost their customers to these sources of information.

Stamp duty incentives

The UK Green Building Council has developed a proposal that identifies moving into a new home as an important trigger point when it is often more convenient for homeowners to make home energy upgrades as they are likely to be making other changes to the property and will also have access to finance through their mortgage. 

The UKGBC proposal goes beyond engagement and information provision and offers a Warm Homes Stamp Duty Incentive that would give homeowners a rebate for any improvements in energy efficiency delivered in the first two years. 

As our message testing showed, financial incentives are clearly an important factor in encouraging households to consider energy improvements and estate agents and the local council would be well placed to inform homeowners about the scheme. Local authorities are increasingly offering energy upgrade advice or partnering with other organisations to provide the service.

More information is available from the UK Green Building Council [8].

Lessons from always-on awareness campaigns

Always-on campaigns help to build awareness over time so that when homeowners are considering changes to their home they are more likely to be aware of different home heating options and know where they can get more information. In reality these campaigns are also targeted to reach particular audiences based on the times and places where the adverts are used. As such, they are similar to some of the activity and messaging used in the Which? campaigns, however they are less likely to specifically reference a trigger point in their messaging.

Analysis of these campaigns can help to inform more targeted campaigns. This can include insight into the audiences that are more receptive to messaging and the messages that have most resonance with different groups.

The government’s Warm and Fuzzy campaign was launched in March 2025 and uses the voices of real homeowners portrayed as stop motion knitted characters to describe the benefits of installing a heat pump in their homes. The campaign runs across multiple media channels and is increasingly offering insights that are shared with other stakeholders through cross sector groups and discussions.

7. Conclusions and recommendations

The way UK households use energy is at the start of a major transition to electrification.  This will impact on the way homeowners heat their homes but also give them the opportunity to generate and store their own energy through solar panels and batteries. Ultimately this can bring benefits for homeowners but it will involve costly and complex choices.

Heating will be an important part of the transition, but our research shows that many consumers aren’t planning ahead for the replacement of their boiler and this means they won’t have the time or support to consider their options. The UK government is currently running the Warm and Fuzzy campaign that raises awareness about heat pumps, but our research suggests there is also an opportunity to use more targeted ‘trigger point’ interventions to engage homeowners.

Consumers are more open to consider changes to their heating at ‘trigger points’ when circumstances mean it is more convenient. Engaging homeowners at these points and providing prompts and clear information helps them to engage with a difficult topic and make more informed decisions. Our research and testing found:

• The right messaging can significantly increase engagement. Our testing of different messages around boiler replacement showed that the optimal set of three messages could deliver 87% engagement.
• Our campaign demonstrated that highlighting the benefits tends to generate higher engagement
• The response from including the campaign in our newsletters showed that communications with consumers that have already expressed an interest in an issue and that have an existing relationship with the organisation delivers high engagement.
• Providing a clear action is also important. Our spring campaign linked through to our Home Energy Planning Service that guided consumers through their choices and provided the option of advice more tailored to their property and needs. 

Recommendations for governments, businesses and organisations in the energy sector

Replacing an older boiler and Spring home improvements are two important trigger points, but they are not the only opportunities to engage homeowners that may be considering home energy improvements. Moving home and major home improvements are also important trigger points when homeowners are more likely to consider changes.

• Governments and businesses should develop strategies for how they will use trigger points, through communication campaigns or more systemic changes, to engage and support homeowners so that they are aware of the home energy improvements they could make and have the information and advice to make informed choices.

Trigger point strategies should:

• use data to identify when homeowners may be at a trigger point. This could include information about the age of their heating system, if they are applying for permission to make changes to their home, or if they are moving home. Data can also be used to better understand homeowners behaviour around trigger points. This data may be held by public bodies or businesses.
• create partnerships with the businesses and organisations that engage with consumers at these times so the information and advice is available when and where consumers need it. This could include energy providers for boiler replacements, DIY stores for home improvement projects, or estate agents and surveyors for moving home
• build on the findings from existing home energy campaigns run by governments, businesses and organisations to develop effective messaging. 
• work with organisations that homeowners trust, as homeowners are more likely to engage with advice from these organisations.
• provide easy access to good quality information and advice that is tailored to the property and the householders needs.

Footnotes 

[1] The transition will impact on most households including homeowners and renters. This report focuses on homeowners as they will be responsible for making the necessary changes to their homes.  ↑

[2] Boiler Upgrade Scheme statistics: March 2026, gov.uk  ↑

[3] Warming up to change, Which? 2025.  ↑

[4] The Warm Homes Plan revised down government targets for the purchase of heat pumps from 600,000 installations a year by 2028 to 450,000 installations by 2030  ↑

[5] Trigger points have been recognised as an opportunity to engage homeowners for several years Energy Saving Trust (2011) Trigger points: a convenient truth  ↑

[6] Output of Total unduplicated reach and frequency. Base size = 1190. All homeowners who singly or jointly make decisions about their heating systems  ↑

[7] How unlocking the Gas Safe Register data could accelerate the UK’s clean heat economy, Project Ambient.   ↑

[8] Warm Homes Stamp Duty Incentive, UKGBC  ↑