FST JOURNAL

Moving towards net zero is a massive multi sector challenge and a lot of progress has already been made. One of the more challenging areas is decarbonising the built environment, partly because buildings have a long-life span and have millions of separate owners. The majority that will exist in 2050 have already been built so we have a large retrofit agenda as well as designing new buildings. On Wednesday 21st May 2025, the Foundation held an evening discussion at The Royal Society to explore how (with a policy backdrop of the government's Warm Homes Plan), social science and engineering could contribute to solving this challenge.

Speakers included:

• Professor Paul Monks, Chief Scientific Adviser at the Department of Energy Security and Net Zero [Chair]
• Professor Jennifer Schooling, Professor of Digital Innovation and Smart Places at Anglia Ruskin University
• Helene Gosden, Associate Director, Retrofit at Scale Taskforce Leader at Arup
• Professor Chris Wise FREng, Senior Director at Expedition Engineering and the Useful Simple Trust
• Professor Mari Martiskainen, Director of the Energy Demand Research Centre at the University of Sussex.
  
  

The evening’s Chair, Professor Paul Monks explained that the UK has the oldest and leakiest housing stock in Europe, but in addition to this, really understanding the social and behavioural aspects of this mission is key. Houses are more than just their fabric and people are the driving factor.

The first speaker, Professor Jennifer Schooling, began by stating that the challenge is above all, a socio-technical challenge, with people at the centre.

The people at the centre of the challenge are householders, homeowners, the retrofit supply chain, product manufacturers, and local authorities, all of whom play crucial roles. According to a 2023 Housing Survey, the UK has 25.4 million households: 64% owner-occupied, 19% privately rented, and the rest, a type of social housing. This translates to approximately 16 million individual homeowners, 4.7 million in the private rented sector, and 4 million in various types of social housing.

There is a significant age diversity in our housing stock. Nearly 9 million homes were built before the end of the Second World War, around another 9 million constructed between the end of the war and 1980, and a smaller number built after 1980. This spans various building codes, many of which were established after these homes were built.

As a result, we see a wide range of skills and technologies available at the time of construction. Additionally, there is a variety of property types involved - everything from small and medium-sized terraced houses to semi-detached, detached homes, bungalows, converted flats, and purpose-built high-rise buildings. This diversity presents a complex challenge as many people need to come together to address a multifaceted problem.

So, what can we do about it? We need to build confidence in the retrofit supply chain, and we required a skilled workforce for it. We must invest in the skills of our suppliers and build trust among property owners. One key approach is to aggregate demand, something Professor Schooling termed: ‘community buying schemes.’ By aggregating demand and possibly segmenting it by locality and property type, we can provide the supply chain with the confidence it needs to invest in upskilling, recruiting, and building capacity. For instance, through a community-based scheme, we could create frameworks for groups of vetted supply chain practitioners. This framework establishes a trusted group of providers, which could reassure homeowners.

Retrofitting can often fall into the ‘too hard’ category. Professor Schooling used a personal anecdote to illustrate how, if there was a community scheme in place, homeowners could participate and rely on the scheme to handle the hard work. She said that her experience with community buying schemes made her a strong advocate for them. In Cambridgeshire (where she resides), the county council enabled a community buying scheme for solar power. It had been straightforward, and the additional reputational aspect of the work created a system where the supplier had been motivated to do a good job because their future opportunities depended on maintaining a positive reputation.

The second speaker was Helene Gosden. She explained that while we know the technical steps needed to decarbonise a home, there are many other considerations that complicate the situation. She said that we must tackle questions such as: Who pays for the work? How do we deliver it? How do we convince people to allow us access to their homes for the required work? Helene’s task force started by identifying the key challenges within this system and focused on six areas to guide efforts. These include:

1. Data: Understanding the baseline condition of our housing stock.

2. Finance: Determining who pays for the retrofitting and how we can demonstrate value and return on investment.

3. Supply Chain: Overcoming fragmentation and encouraging investment, especially from small and micro enterprises.

4. Neighbourhoods: Enabling communities to act from the grassroots level and supporting local initiatives.

5. Materials: Being mindful of the additional embodied carbon that could result from retrofitting efforts.

6. Human Behaviour and the User Experience: Acknowledging that these structures are more than just assets; they are homes.

Housing sits at the nexus of climate change and social equity. There are many benefits to good housing, and thinking broadly about the reasons to intervene means more action and benefits. These include thriving, more equal populations, better climate resilience, and jobs.

We need to scale projects to the level of neighbourhoods, where actions multiply benefits. When you think about a community, the benefits begin to scale exponentially. For example, there is potential for microgrids and demand-side flexibility to lower overall grid demand. We also see a reduced burden on health and social care systems due to warmer homes in winter and cooler homes in summer. Additionally, investments to create and expand green areas in towns and cities help to reduce the urban heat island effect, leading to less cooling demand in buildings. The "co-benefits" of retrofitting should be recognised as core benefits of community decarbonisation at scale.

Looking next at the Warm Homes Plan, Helene explored the flagship Social Housing Decarbonisation Fund (SHDF) and the Home Upgrade Grant. She said that these programmes are world-leading in their scope. The SHDF supports local authorities and housing associations, while the Home Upgrade Grant is aimed at low-income privately owned homes and channels through local authorities.

Over the last two years, Helene noted that one of the critical success factors for the SHDF has been tenant engagement. It is essential to bring tenants along on this journey and help them understand how the disruptions will benefit them—by reducing bills and enhancing comfort and health. It is all about winning hearts and minds. Grant recipients who recognise the value of this engagement and plan for it early see less resistance and greater satisfaction, creating a positive feedback loop that makes future conversations easier. On the other hand, the key challenge for the Home Upgrade Grant lies in identifying eligible homes. Since those homes do not belong to the local authority, engaging with homeowners and keeping them in the customer journey is difficult. The conversion rate from an expression of interest in the Home Upgrade Grant to completed retrofitting is quite low.

Building trust involves fostering relationships, ensuring quality delivery, and maintaining good communication. We need an army of advocates within our communities. There are community organisations doing valuable work, and their energy needs to be harnessed and supported. They should work together, rather than trying to tackle the same challenges in isolation.

The third speaker, Professor Chris Wise discussed design, designers, and what we can do to instil confidence in people that there are practicing experts working to address the challenge of decarbonising buildings, in practical terms.

He said that systems integration in design is currently not well developed. To illustrate this, he referred to a slide from a study conducted by the University of Cambridge, as part of their industrial steering group. In one aspect of their research, they analysed a hypothetical building in a city centre, measuring 10,000 square metres, and found that different codes for ventilation, space planning, fire safety, and structural integrity produced vastly different occupancy figures.

Professor Wise said that our mission should be to bridge these compartmentalised professions to establish a system of integration. We should acknowledge the unknown factors or considerations we had not yet identified, which need to be included in our framework.

Over time, the world has grown increasingly complex, leading to a rise of specialised compartments. This vast array of boxes has become increasingly unstable, risking the collapse of the overall system. Even when we attempt to incorporate regenerative design, biodiversity, and other factors, the instability remains. Professor Wise believes that a better approach is to layer systems over one another. Within Ian McHarg's 1969 book, "Design with Nature," the author analyses not just the physical systems interacting at a location, but also social factors like crime, poverty, well-being, and health, with the goal of understanding the connections between these systems in a way that fosters development without conflict. As part of landscape and architecture practice, Professor Wise said that we should strive to support these systems and promote their co-development.

Professor Wise has worked on several well-known and progressive architectural projects, including the Millenium Bridge, the world’s first green ecological skyscraper, in Frankfurt and the Velodrome in London. Discussing an ongoing project - South Ken's N+, (which focuses on South Kensington and Albertopolis in London), he said that this initiative involves all 23 institutions in the area, including several museums and Imperial College who collaborate on a neighbourhood-scale project for Net Zero, circular economy, sustainable transport, and nature-positive initiatives. The teams have been working on this for three years and are making significant strides.

In the process of collecting emissions data for this project, it became clear that many institutions were unaware of how their emissions compared to best practice. The project also conducted surveys to establish a benchmark for biodiversity, from the South Ken N+ park down to the new garden at the Natural History Museum.

Lean design, which emphasises using only what you need, is often overlooked. Professor Wise argued that this was evident in existing codes of practice. Additionally, many technologists tended to over-design due to time constraints in the commercial landscape, leading to inefficiencies. The MeiCon study at Cambridge found that designers were over-engineering by 25-30%.

The final speaker, Professor Mari Martiskainen, emphasised that the reason we were discussing warm homes was to ensure that our homes were resilient in the face of climate change. She displayed a photo taken from BBC News, during the wildfires in Los Angeles and said that it served as a devastating reminder of what was happening at that moment.

Despite some recent political trends, there is significant public support for climate action. For example, Professor Martiskainen said that the UNDP found that 80% of people globally wanted their country to take greater action on climate change, and 72% wanted to move away from fossil fuels. Many individuals want to act on climate change, and we need to make clear that our homes are part of that solution. It is essential to think beyond just bricks and mortar. As a social scientist, Professor Martiskainen is concerned with behaviour inside and outside of the homes as well as a ‘just transition to net zero’ which she says simultaneously addresses inequalities while moving towards low-carbon interventions that prioritise restoration, reconstruction, and redistributive justice.

Justice is subjective; it varies from person to person. Ie: What does it mean to have a just transition toward warm, sustainable, and low-carbon homes?  Who are the individuals we expect to act in this area? Are they homeowners, tenants, or landlords? It is crucial to recognise that people have very different starting points in terms of improving their homes or making their homes for more warmer or cooler in a heating planet. In research conducted by her colleagues, Professor Martiskainen found that trusted relationships are extremely important. For example, in the UK, people tend to trust individuals they already know, more than they trust the government, businesses, or the media. She said that it is therefore crucial to foster greater confidence in low-carbon homes by leveraging the trust that already exists within people's social networks.

Another critical aspect is to communicate in straightforward terms. For instance, we should avoid jargon like "kilowatt hours" or "retrofit”, as many people outside of academia or the energy field may find such terms confusing. Instead, we should explain what these concepts mean in practical, everyday terms.

There remains a disconnect between the complex government policies and the positive local actions we are observing in our case studies. We believe that while local initiatives can foster trusted action, they require substantial time, resources, and specific skills, particularly in terms of interpersonal relationships and the technical knowledge needed for the intricate aspects of building improvements.

We must be mindful of who can act. While we are witnessing an energy transition, we must be aware that not everyone is currently involved or has the means to participate. It is crucial that we address this gap to ensure that everyone can contribute to the collective effort towards low-carbon homes.

To listen to the Q&A and debate that followed the presentations, view the full event recording here.