Mears Group PLC
Decarbonisation Report

Warmer, healthier homes - domestic retrofit, a net zero opportunity

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What is domestic retrofit?

The process of making improvements to a home so that it becomes more energy efficient and operates with lower emissions.

This presents a big opportunity for the UK both in terms of economic and social value.

What does net zero mean?

A dictionary definition reads that it is completely negating the greenhouse gases produced by human activity.

A greenhouse gas is a gas that contributes to the greenhouse effect by absorbing infrared radiation. In essence, they raise the surface temperature of the planet.

The Decarbonisation Challenge

Net zero is a complex systems challenge. When we talk about the decarbonisation of our energy system, we first must understand what is currently in place, how it presently operates and acknowledge how everything is interconnected, from heat, power, transport through to the infrastructure that connects them. This means that any decarbonisation activity undertaken in any one part of the system requires an understanding of the reaction and effects within another part of the system.

Net zero is a systems challenge that requires a whole systems solution

Housing will need certainty and a pathway to contribute positively to net zero

Requires long-term planning and a clear roadmap to deliver net zero

Housing is part of the wider eco system transition to
net zero

The dual challenge facing housing

We face a volume challenge in the retrofit of existing properties
We need to build new homes now which are low/zero carbon in construction and operation
We should not look to add to the retrofit challenge through poorly designed new housing
Solutions we employ must be scaleable

When we look specifically at housing and its role in the net zero transition, there are two clear challenges that we must accept and overcome. The first is how we ensure that all new homes we build are low to zero carbon in construction and operation. The second is how do we ensure that the housing stock that already exists today that will still be in existence and use in 2050 is made to be energy efficient and low carbon in operation.

New build

As we have noted, the sector already has a big enough challenge facing it with retrofitting existing properties that will still be in existence in 2050, without adding to it with properties that we build today that will need forms of upgrades in the coming decades.

Housing is also coming more to the forefront of the current political debate. Ahead of the next general election, the political parties have begun to talk about the level of housebuilding they see is required across the country. Irrespective of the number and the party in power it becomes vital that these homes are built to low and zero carbon standards if we are to meet our legally binding net zero 2050 target.

Need for standards to drive change and create a consistent approach

We understand the retrofit challenge, let’s not add to it with inefficient new builds

What is retrofit?

What exactly is retrofit? What does it mean? Is it the best phrase to use to engage people in changing their homes, their approach to heating those homes and adopting the subtle behaviour changes that will come about from adopting low carbon/renewable heating technology?

One definition of retrofit is – add (a component or accessory) to something that did not have it when manufactured.

Key themes around retrofit:

Need to take a long-term view with a long-term stimulus to deliver

The use of the correct language for resident engagement is important – we  should seek to make retrofit an aspirational activity

Look beyond retrofit as simply a technical proposition - retrofit is a very human experience

It takes brave leadership to drive retrofit forward

What have we learnt to date from retrofit?

Firstly, we must acknowledge that here at Mears we continue to learn daily as we undertake more and more retrofit activity. We are beginning to see this now as a scalable activity. It has grown slowly over the years, and its demand has grown in line with greater funding being made available from government.

At times it still feels like an embryonic market which brings with it a natural nervousness. This is where a more open approach to collaboration across the sector could make a big positive impact.

Certainty is needed in both policy and funding landscapes

To scale retrofit we need a consistent approach across the industry

We continue to learn daily, job by job

There is no one size fits all solution

We need retrofit to be a true collaboration and for all parties involved to be prepared to share learnings and learn from each other to make this a process that delivers for all.

You need to start with data

Good decisions tend to be made on the back of good quality evidence. This is why the collation and interpretation of good quality data is such a vitally important component of the net zero journey. It is at the heart of good intelligent decision making based on clear evidence and helps form effective asset management practice. Simply put, without the true understanding of the housing portfolio and stock, it is hard to make well-informed decisions on what to do with it to make it low carbon.

Evidence is key to effective decision making

Good data is vital to make informed decisions

Better sharing of data will help inform the sectoro

Technology solutions for retrofit

The first thing to note when we talk about technical solutions for retrofit, like most things there is no one size fits all solution. The solutions for retrofit will come from a complementary set of technologies and approaches and their employment will be guided by both geographical energy infrastructure and tailored by the retrofit need of each building.

Most energy system models identify electrification as the preferred route for decarbonising heat. If this is the case then we will be working with a number of known, but presently underdeveloped and under commercialised technologies.  An increase in retrofit activity and demand will lead to an increase in the efficiency and cost-effective nature of the technologies involved.

Innovation  will continue to refine our technology approach
EWI and fabric first is currently the most popular approach to retrofit
Electrification of heat is the most likely net zero approach
Need to break technology myths, especially around heat pumps


A wealth of skills is needed to deliver retrofit

Need investment in training to not only train new recruits but also upskill

We should focus on the social value of retrofit to attract people into the sector

Retrofit is a long term career opportunity


The sector needs to show its attractiveness to private investors

Housing sector has a number of competing funding priorities

A long-term approach to funding retrofit is required

We need new funding models and approach to deliver retrofit


When we talk of decarbonisation – no one technology, no one government, no one organisation can deliver it in isolation. It is too big and the energy system and economy too interconnected to deliver in silos. It requires partnership and it requires collaboration to deliver it. Including service providers to the social housing sector.

Volume of retrofit means it can’t be delivered by isolated parties

Break the perception of any competition this is a collective challenge  
we need to overcome

Should expand the impact of collaborative bodies like NHDG and the National Retrofit Hub

Only achieve when everyone reaches net zero, in our interests to work together


How do we look to design effective retrofit programmes?

We should look beyond the simple single property approach and look towards the wider impact of retrofit to inspire our thinking and approach. The benefit of retrofit does bring with it an individual benefit to the resident or homeowner, but it is the cumulative benefit to the community that should drive our overall approach, as this is where the greater impact is felt.

Retrofit is technical in nature, but it has a real human impact

Need clear standards for all to use, to create a consistent approach to retrofit

Need wider levels of dissemination of learnings across the sector

Standards can drive wider change than subsidies


How do we get people interested and then excited about retrofit?
It requires open and honest conversations. We have highlighted the level of change involved with retrofit, so we should be clear and engaging with people as to what it means for them, what it means for the wider community and then what it will mean for the wider environment.

Tenants and residents have to understand what is in it for them

Understand the resident, their needs and their motivation around retrofit

Landlords and service providers have experience in engaging residents, use their knowledge

Use simple "human" language

What other housing issues could retrofit solve?

When we look at the to do list for an asset manager in housing today there are a wide range of issues they need to address. Today, carbon reduction and tackling damp and mould are key strategic challenges that housing providers are grappling with, but should they be looking at them in isolation? Can retrofit provide a solution for damp and mould as well as for other housing issues, whilst reducing the level of carbon emissions used in the heating of our homes.

We have identified that retrofit is not just a benefit to the physical property itself, it provides benefits to an individual’s life. And it does not just stop at the individual either, it can have multiple positive benefits to the wider community as well.

Retrofit provides a platform for integrated asset management
Should take a wider holistic view to housing challenges and avoid tackling each aspect in isolation
Retrofit can provide a solution to wider housing issues such as damp and mould

Conclusions and recommendations to deliver effective retrofit?

As we have written this report, some themes have become very clear. When they are written down, they seem quite basic, but that is part of the dilemma about the net zero transition. We do not deny that the delivery of solutions will be difficult and technical in nature, but we run the risk of over complicating the vision of what net zero and what retrofit should be.

Retrofit is about improving lives. It is about improving the viability of the asset (the home), it is about invigorating the community – it is at the end of the day about healthier, warmer, better ventilated, cheaper to run homes – that do not damage the environment.

To achieve these aims we recommend that:

Retrofit is delivered through long-term planning and thinking

Given the volume of homes that need to be retrofitted in both the social and affordable homes sector and beyond, it can only be achieved with the support of long-term policy support.

Retrofit is viewed as a volume challenge

Recognise that we are currently behind the curve and focus efforts on making retrofit a sector that works at pace and at scale.

Standards drive behaviour

They have the potential to have a bigger impact than any financial subsidy, because they can drive consistency across everyone’s work.

We concentrate on using clear communication and language

Given the volume of homes that need to be retrofitted in both the social and affordable homes sector and beyond, it can only be achieved with the support of long-term policy support.

Base decisions on retrofit on evidence

Invest in and ensure you get your data right. Without this, retrofit activity could cost more and the benefits it can provide not fully recognised.

Retrofit is viewed as being more than just technical

Whilst the application of the measures to the property are physical and technical in their nature, do not lose sight of the positive impact that retrofit has on the resident.

Break any perception that retrofit is a competition

Place a clear focus on collaboration and view the actual target as the total number of homes the sector needs to decarbonise, not just those of an individual housing provider.

We engage tenants by focusing on their needs

Retrofit should not be about what organisations want residents to do, rather we should focus on encouraging the motivations of residents to undertake the process.

New funding models are created

Based on a long-term calculation of the value of the retrofit investment.

Make retrofit and the social housing sector appealing

To highlight how retrofit is a growing industry and one that has a strong future, emphasising why it should be seen as a viable career choice for the future.

Place an emphasis on
the social value of retrofit

Both to attract residents to participate in the programme, but also to act as a mechanism to attract new talent into the industry and the sector.

Housing providers take a holistic view

Don’t isolate housing issues. Use retrofit as a mechanism to deliver true integrated asset management.