How can the construction sector meet the UK’s net zero commitments on time and within budget? And where do the main challenges lie in terms of implementing sustainable practices, greater circularity, and a greener supply chain? These questions were addressed by a panel of experts at a round table discussion in London hosted by AT in partnership with AccuRoof.

Round table participants

According to a report published by the UK Green Building Council (UKGBC) late last year, the UK built environment industry is ‘significantly off-track from the trajectory required to meet the country’s national net zero commitments’. Even more worrying, it highlights a ‘substantial gap in national policies that could make or break the built environment’s efforts to meet the required decarbonisation pace and scale’.

As anybody working in the construction sector knows, there are still major challenges to implementing sustainability and achieving net zero on building projects. So where do the main issues lie? What are the current barriers to circularity? How should we measure whole life carbon? And what can be done to implement and maintain a green and ethical supply chain? These questions and more were addressed by a panel of experts at a round table discussion in London hosted by Architecture Today in partnership with AccuRoof, the specification arm of SIG Roofing.

Selected for their diverse experience and perspectives, the round table participants comprised representatives from architectural practice, engineers (environmental, façade, and structural), developers, and an environmentally-focused deconstruction specialist.

Rosie Scott and Anna Lisa McSweeney (photo: Robin Bell)

Commercial preferences
The discussion started with AT Editor and chairperson Isabel Allen asking the panel what they thought needed to happen to persuade those involved in procuring and designing buildings to adopt a more circular approach. White Arkitekter’s Anna Lisa McSweeney was the first panellist to respond, advocating a ‘mindset shift’ across the industry requiring systems thinking rather than a ‘business as usual’ approach. She said that in the current market it was important to show clients where circularity could be of financial benefit in respect of reducing time spent on site when reusing an existing structure. From a project perspective, McSweeney recommended assessing existing assets for reuse, sourcing materials responsibly and innovatively, and reducing uncertainty by relying on more localised local supply chains.

Robert Delius of Stride Treglown – one of the UK’s largest practices – revealed that its clients were increasingly choosing retrofit over new build for environmental reasons, and that this change of direction would have been inconceivable only five years ago. He said that the practice was becoming more selective about who it worked for, while also questioning the types of projects that it was involved with, particularly those intended for greenfield sites.

Sandra Sezgin of British Land gave the first client perspective of the day, explaining that the company has a ‘refurbish-first’ approach, due in part to the market’s move away from long leases to shorter letting periods. It is also focusing on decarbonising its existing building stock in line with its net zero commitments and driven partly by tenant demand. She said that one of the many benefits of retrofit over new build was that incoming tenants felt, that with the right specification, they could still obtain ‘a new product in an existing building’. One of current challenges Sezgin identified was getting the circular market to supply materials at the right time.

David Illingworth of London Structures Lab enquired whether tenant demand for decarbonisation was related to embodied carbon or carbon in use. Sezgin said that it was primarily carbon in use, i.e. operation of the building. However, tenants were becoming increasingly interested in the wider story of retrofit over new build, and the environmental benefits that this could bring. Illingworth also made the point that larger property companies, such as British Land, were able to take a long-term view of asset management and retrofit developments, while smaller companies that did not retain assets or have estates were often unwilling to invest in enabling works that could be worth nothing when the building was sold.

David Illingworth and Harry Sumner (photo: Robin Bell)

The importance of partnerships
Isabel Allen picked up on this point, asking Rosie Scott if Derwent London’s responsible and enlightened approach to asset management had changed the way it commissioned consultants. Scott responded by saying that the company had always viewed its consultant teams as long-term partners, and had used the same design teams for the last 30 years. While she admitted that consultant teams did inform the company, much of the drive towards circularity was ‘from the top down’ i.e from Derwent, its shareholders and the market. Scott explained that the company had established more consultant frameworks in recent years to deal with the constant flow of refurbishment and fit-out schemes, and to make the work more economical and efficient for everyone involved.

Louisa Bowles of Hawkins\Brown concurred that the long-term partnership approach was highly beneficial in advancing circularity, and something the practice had championed with a number of its clients – not least in the commercial and higher education sectors where clients own and occupy portfolios. She also made the point that architects’ extensive knowledge of the building fabric and what materials can and can’t be used meant they were well placed to provide specialist advice on circularity and a more joined-up approach to retrofit projects in general. Bowles revealed that the importance Hawkins\Brown places on its own embedded sustainability approach had led the practice to rename its team of dedicated specialists as the Environmental Intelligence team to better reflect the distinct set of skills it offers to the design process.

Daniel Bosworth and Louisa Bowles (photo: Robin Bell)

Scott confirmed that as a client, Derwent invariably sought consultants that could bring an interdisciplinary approach to its projects, particularly in the area of sustainability. She sited Piercy&Company’s in-house partnership with Materials Assemble as a good example of this. RSHP’s Lorna Edwards spoke about the pressure architects are currently experiencing in terms of fees, with additional work required for detailed whole life carbon analysis and the responsibilities of new legislation, such as the Building Safety Act, potentially requiring significant resourcing to undertake. She reiterated Scott and Bowles’ earlier point, that established and closely aligned consultant teams offered the best chance of success, and advocated the use of financial incentivisation to reward the completion of key stages, such as planning approval, and the achievement of specific targets, including environmental ones.

Lorna Edwards and Daniel Sweeney (photo: Robin Bell)

Taking responsibility
McSweeney posed the next question: who should be held responsible for the carbon in buildings? Scott responded by saying that Derwent does not impose carbon targets on its tenants for fitouts – rather it gives them guidance on low-carbon materials and circularity. Furthermore, the company is increasingly asking tenants not to strip out or reinstate works when they leave, so materials can be reused and repurposed.

Knowledge is power
The lack of information about products within built assets as a barrier to circularity was the next topic introduced by Allen. Deconstruction specialist Daniel Sweeney of John F Hunt Group explained that the data is being captured but then transposed onto a multitude of different platforms and carbon calculators depending on the client organisation. He said that pre-demolition audits were useful (especially when commissioned early on) as they could be reviewed and then form part of the tender process. However, they also needed to be combined with testing and evaluation procedures to accurately ascertain the reuse potential and price of specific materials, such as bricks. According to Sweeney, one of the biggest challenges was uncertainty: would the materials removed from a demolition site find a new home elsewhere? Scott agreed, stating that certainty regarding the reuse of materials needed to be established early on in the procurement process in order to avoid additional costs, lack of approval, and subsequent deletion from the scope of works.

Sandra Sezgin (photo: Robin Bell)

The role of manufacturers and suppliers
SIG UK’s Lorna Stork asked Sweeney how involved manufactures were with the potential reuse and recycling of their products from demolition sites. His response was that while some companies did have take-back schemes, they tended to be larger in size with the necessary resources to facilitate this. Stork explained that from SIG’s perspective, material take-back is currently being undertaken on a trial basis that was dependent on geographical location, the specific targeting of one or two products, and commitment from the entire project team, including the client and main contractor. Stork felt that this was achievable with simple materials, such as plasterboard, but highly challenging when it came to more complex products and systems. She advocated successful local trials, before expanding outwards geographically, to ensure a balanced carbon lifecycle model.

Lorna Stork (photo: Robin Bell)

Managing risk
On the subject of complexity, Andrea Botti of Stanton Williams made the point that some manufacturers of aluminium and glass façades had implemented take-back schemes, and they were championing these more than other players within the construction market. Elsewhere, other companies were maximising the recycled content within their products, giving further reasons for hope across the industry. According to postdoctoral researcher Rebecca Hartwell, one of the principal reasons why contemporary façade systems are invariably returned to manufacturers – rather than being reused – is due to uncertainty in future demand for systems designed with reused components. Reused systems or components are often associated with high levels of perceived risk by main contractors, thus limiting their demand. The more simple, adaptable, and durable the product, the easier it is to accommodate the risk. Hartwell pondered the need for a new and as yet unmatched role or stakeholder who would not only be responsible for the performance testing of existing materials and components, but also facilitate storage and supply.

Scott felt that further progress in this area would be dependent on clients who were willing to forgo warranties, particularly on lower risk items, such as fan coil units, which could be evaluated and successfully reused over relatively short time scales between commercial fit outs. Educating both clients and tenants in this area would be key to a successful outcome, she said. Bennetts Associates’ Harry Sumner made the point that greater flexibility in relation to performance specifications would accelerate the reuse of existing assets, such as raised access floors and façades, while also significantly helping with the issue of upfront carbon.

Rebecca Hartwell (photo: Robin Bell)

Edwards agreed, saying that over specification was another barrier to lower carbon buildings. Scott felt that this was being driven in part by building regulators and insurers, and it was important to ascertain who and what the key drivers were for this in order to bring about change. Illingworth underlined the dangers of structural over specification on retrofit schemes, which may or may not have been utilised by subsequent follow-on trades.

Meanwhile, Bowles identified the lack of specific environmental data on many green and bio-based materials; in many cases because the suppliers are small, niche businesses that do not have the funding and time available for testing and certification. She revealed that in some cases Hawkins\Brown estimated the upfront and embodied carbon emissions for products it wanted to support the use of, from raw ingredients and manufacturing data, in order to improve the specification process and aid material comparisons. Lack of fire data and certification was another significant barrier to specifying innovative new bio-based materials, especially on larger scale projects with specific performance requirements she said, with Illingworth calling for government-backed funding to deal with this acute issue. A far more centralised approach could be taken to support testing and innovation for smaller providers in the supply chain.

Daniel Bosworth and Andrea Botti (photo: Robin Bell)

Going the distance
As the conversation turned to the supply chain, AccuRoof’s Daniel Bosworth said that waterproofing products, such as single ply membranes, were invariably replaced – rather than reused – because they had reached the end of their service life. In the case of single ply, around 15 per cent of recycled roof material could potentially be fed back into the manufacture of new membrane products. In terms of materials that could potentially be reused, Bosworth flagged up XPS and EPS insulation found within inverted roof systems. However, he cautioned against bonded warm roof systems in terms of pure reusability, due to the non-dismountable nature of the construction processes. Choosing mechanically fixed systems, he felt, could offer greater potential for component reuse over the long term. Bosworth also stressed the environmental benefits of specifying highly durable roofing systems, such as hot melt, which have the potential to last the lifetime of the building.

Supply chain transparency
On the question of supply chain transparency, Bosworth commented that AccuRoof was as open as it could be in terms of sharing information between project team members. From a practice perspective, Edwards explained that RSHP endeavours to share information across project teams and the wider construction industry. She advocated closer ties with supply chains to ensure deliverability, and the use of performance-based specifications to ensure key products and systems are not ‘swapped out’ further down the line for reasons of cost or expediency.

Back to the beginning 
The circular nature of both the subject matter and the round table discussion was echoed in the closing words of McSweeney. “We need to stop thinking about the circular economy in terms of simply avoiding landfill,” she said. “It’s about retaining the value of things and keeping them over a long period of time. Recycling takes a lot of energy, so building assets need to be reused wherever possible in their existing form.”

The AccuRoof team can be contacted on 0845 869 4887, by email or via the website.

Participants’ responses