Watch our webinar, in partnership with Sika UK, exploring ways of maximising cradle-to-cradle design.

This Architecture Today webinar, supported by Sika UK, explored how practitioners can engage with supply chains to make ethical and sustainable specifications, while also making the most of cradle-to-cradle design. The first speaker, David Cheshire, director of AECOM, argued that the best mines are not those dirty holes in the ground that produce ores requiring enormous amount of refinement. They are in fact, our cities, and take the form of our existing building stock. ‘There is a massive stock of materials and resources in our cities and towns,’ he said. ‘It is far denser than if we mine it. We need to think of the whole city as a stock of materials.’

Speakers (from left to right) David Cheshire, Dominik Campanella, Lucy Bagshaw, Richard Aldred, and Tom Webster

This is a key part of thinking about our buildings as part of a circular economy. Rather than using them, demolishing them and downgrading the resulting materials, we should first preserve and re-employ as much as we can. If a building does have to be knocked down, then its elements should be preserved and re-used as far as possible.

This approach has major implications for design. ‘As designers,’ Cheshire said, ‘we are inherently creating a concept of waste if we are not thinking about the next use of components and elements.’ This leads to a requirement not, for example, to bond different materials together, and to fix steel with bolts rather than welding.

Diagram showing circular economy principles

Digital approaches are also important, such as work being done by the University of Exeter mapping all the bricks in Bradford. Cheshire also described an exciting research project taking place in Amsterdam, crushing concrete to extract the un-hydrated cement so that it can be used again.

Lucy Bagshaw, associate director at TP Bennett, talked about the circular economy and cradle to cradle construction in terms of commercial fit-outs, which currently have an average lifespan of just seven years. One easy win is to agree what is wanted with a landlord prior to re-letting to prevent a futile landlord’s fitout that is ripped out immediately. The architect said that she is seeing a lot of interest now from clients in keeping things rather than replacement. On one project, she said, ‘We explained the amount of carbon that would be saved by retaining partitions and ceiling panels. They agreed to work with what was there. This saved over 30,000kg of carbon.’

London office for non-profit company designed by TP Bennett (ph: Hufton + Crow)

Bagshaw talked about all aspects of a project, from concept design all the way through to handover and use. ‘Communication is key,’ she said. ‘Rigorous and careful specification is critical’. It is, she added, ‘critical to make tender specifications really robust so that a chosen sustainable product isn’t switched out .’ Asked in a question whether we need to go back to absolute specifications, she said that she said she didn’t think this would always be possible – not least because of lack of knowledge, but she was concerned that ‘contractors and subcontractors don’t always buy into all the specifications.

The first ever Cradle to Cradle Silver Certified roofing membrane, Sarnafil Advanced Technology from Sika underwent a rigorous testing process

The next speaker talked about one product in particular. Richard Aldred is head of technical innovation and compliance at Sika UK, and he discussed Sarnafil Advanced Technology, which is, he said, ‘the next generation of single-ply membranes. It is available in a range of thicknesses up to 2.5mm which is, he said, the thickest ever produced. The product has, he said, excellent performance and is Cradle to Cradle Silver certified.

Asked by a member of the audience about specifications, Aldred said, ‘We have always struggled to get the right products specified for the right projects. But designers are starting to understand the need to defend them.’

Deconstruction and brokerage digitisation

One of the biggest challenges with cradle to cradle aspirations is how to actually achieve them. Dominik Campanella, co-founder of German company Concular, explained how his company facilitates this. It has a digital platform for circular construction which works to match demand to supply. It can not only help to source materials but also calculate savings and carry out what Campanella describes as ‘scenario assessment’. For example, is it better to re-use older windows with a lower energy performance, or specify new ones that are high performance but with more embodied energy?

Ceilings, lamps and raised floor panels are relatively easy to reuse on building projects

The two key stages in a project are at design and at deconstruction. Certain elements are easy to reuse, said Campanella, such as ceilings, lamps and raised floor panels. ‘You need knowledge about how to deconstruct selectively.,’ he said ‘It is only possible by having a network of different stakeholders, architects, building owners, a deconstruction company, manufacturers and transport. You need a whole network.’

Webb Yates’ Fuente del Jarro factory in Valencia, Spain, was designed using non-bespoke, ‘in stock’ steel from the stockist. This saved money and was key to developing the overall form of the building (ph: Steve Webb)

The last speaker, Tom Webster, director of Webb Yates, concentrated on a single material – steel. Although it is publicised as being sustainable, in fact, he said, it pushes up the embodied carbon in a building compared to other structural materials. ‘In terms of carbon it is not a good performer,’ he said, ‘even though the amount of material is quite minimal.’

Steel is superficially very good in the circular economy because it is 100 per cent recyclable, but the recycling process is energy intensive. Until we can decarbonise the electricity used to recycle steel (estimated date 2050) it is far better to re-use it.

Designed by FaulknerBrowns with Webb Yates, Try Market Hall at Victoria Station, London, has successfully reworked the arcaded bays of Terminus Place into a new food and beverage destination for residents, commuters and tourists (ph: Christopher Horwood)

This requires designers and engineers to think differently. The best thing of course is to re-use structural steel in situ, but where this is not possible, steel will need to be dismantled, tested, certified and used again. Designers will then have to design with what is available, rather than specifying specific elements. It is possible, Webster said, that the role of the structural engineer will become very like that of the services engineer. They will produce a performance specification and the contractor will then meet that with what is available and/ or affordable.

This is just one of the issues to address. But, Webster said, ‘The take home is, if you reuse your steelwork, your carbon footprint for your steelwork is almost nothing’.