The efficient use of materials within the built environment is under constant scrutiny. Added to this are concentrated efforts to work within an improved circular approach to reduce, reuse and recycle. All of this was under discussion at a recent roundtable hosted by Aggregate Industries.
There are many innovations and opportunities to improve and secure long term use and processing of our precious natural resources and essential building materials. The construction – and demolition industry – needs to rethink the way we design, build and ultimately use end-of-life products.
Under the overarching theme of ‘Farming the Urban Quarry’ three key topics under discussion were – material harvesting, circularity and design for deconstruction/reuse – and the key drivers to these concepts, with one eye on the opportunities the offsite manufacturing sector might present in facilitating new ways of thinking about how we design and procure the buildings of the future.
Old buildings = new materials
‘Harvesting’ what already exists and extending the use of materials within our buildings is a society imperative – essentially how can we maximise the built environment we create with a carbon-sensitive eye on the future? “We need to reduce our waste in the first place by extending the life of our buildings and the various elements within them,” said Elaine Toogood, Director, Architecture and Sustainable Design, Concrete Centre. “I certainly think there are huge amounts of collaboration and stakeholder engagement, looking at the challenge of how we can do better. Changes in planning policy can be instrumental in promoting reuse.”
With planners central to decision making and carbon drivers underpinning many changes, there is strong correlation between the circular economy and reducing waste generally, that can boost developments at a project level and at national level to help decarbonise. But new ways of working and implementation are not easy to embed. A change in class specification allowing building conversion from office to residential is a ‘tangible’ thing to happen to extend building life said Urbana’s Chloe Parmentar: “But it doesn’t explicitly reference the fact that it’s the best low carbon option. It doesn’t really talk about the circular economy.”
Is there an appetite from funders to back a building that isn’t new and just convert or upgrade what already exists: are there incentives to push that agenda forward? Conversations are changing but there is a disconnect it seems between the related concepts of decarbonisation, net zero and overall circularity.
What does circularity mean?
“Some of this is just about cleaning up the mess of the linear economy, the stuff we’ve already created,” said Eoin Bailey, UK Innovation & Circular Economy Lead at Celsa UK. “True circularity is designing from scratch and utilising what we already have.” Building regulations, management systems and the various construction protocols need to better incentivise circularity and encourage specifiers to think about buildings from a different perspective.
Ultimately any approach must be cost-effective as well as environmentally effective. But to quantify the value of what already exists, with a view to the future, with more evidence-based reasoning – or even a new commercial or technical model – is required. Pre-demolition audits can only do so much. As with many aspects of the construction world, better data and science-based evidence is needed on what is available in the building today that can be re-purposed tomorrow.
The diversity of materials to ‘farm’ from our built environment is wide – from structural elements to interior fit-out – down to simple everyday items such as chairs or carpet tiles. Decarbonisation is a driver to doing more with this ‘waste’ but is this a correct description when we think of repurposing used material? “They’re valuable resources,” says Eoin. “We need to stop thinking of resources as waste, we just haven’t figured out what to do with them yet.”
It was pointed out that it’s assumed that if anyone is ‘doing recycling’, they’re ‘doing the circular economy’. That’s not the case – recycling should be a last resort. We need to think more about reusability and more ‘adaptability’ and using materials as many times as possible until there’s nothing left to do with it, while keeping a high level of performance and quality.
The feeling is that we need to understand how to utilise materials more effectively and introduce newer definitions of value – e.g. carbon, financial, resource or social values – rather than simple disposal. Incentives for developers to reuse demolition resource seem to still be at bare minimum. If the circular economy – as with offsite construction – can be defined as a system and process, rather than the evolution of a product, what needs to improve?
“What we do need to change is our segregation,” continued Eoin. “How we separate materials when we demolish the building: you need to understand what materials there are and then start talking about quality.” This may need the creation of ‘meanwhile sites’ as temporary storage, or the repositioning of programmes such as the sidelined National Industrial Symbiosis Programme (NISP). This was set up to: “identify mutually profitable transactions between companies, so that underused or undervalued resources (including energy, waste, water and logistics) are brought into productive use.” The basic aim is to seek to connect markets together to divert waste from landfill.
Smart developments
We live in a data age that is constantly gaining momentum and size. Can we simply just communicate better, as Leon Black, Professor of Infrastructure Materials at Leeds University pointed out: “I’ve heard on a number of occasions where there could be steel to reuse, but the storage of it is a problem and if only a potential user could have had a few weeks’ notice, it could have been picked up.” Being able to highlight what is becoming available earlier in a demolition process (weeks/months’ time) could be done digitally relatively easily.
Having a smart policy for change is “easier to say than implement.” Regulations for building waste reuse and deconstruction do need updating plus a change in mindset – this once again includes an education process for the planning fraternity and a clearer understanding of the way materials can be given value and fed back into the supply chain effectively. Complicated metrics are involved in reusing recycled content. But it’s about “planning for the future. If you don’t think about the long-term picture, you’re just setting yourself up to fail.”
This long-term thinking about what a building comprises of and how it be repurposed in the future can be difficult for people to assess. In the commercial sector it can be “quite complicated”, as you’re asking for a client to invest quite a lot at the beginning in the preparation of a building with a view to future reclamation value – but how do you incentivise something that is going to be valuable (potentially) to someone else in 75+ years?
Product innovation and efficiency
As cement and concrete currently account for 7% of global CO2 emissions, innovative materials and processes such as recycled cement paste (RCP) and emerging developments such as the Cambridge Electric Cement – being developed by Cambridge University’s Department of Engineering – where concrete is recycled by reactivating it through a steel recycling process, could have profound implications for precast concrete. The process could potentially produce one billion tonnes per year by 2050, to effectively ‘upcycle cement’ to a zero-carbon product.
But as Mark Hickingbottom Commercial Director, Aggregate Industries points out, these developments aren’t cheap. “To pursue these kinds of innovations, academics and other industry disruptors are being supported by Aggregate Industries, who are investing in 50-plus startups in the UK. These kinds of innovations are starting to accelerate and are encouraging the on-going ‘farming of the urban environment’.
“We really need to continue to make these exploratory innovations more affordable, not just via business backing but also through more focused Government support and incentives for companies embracing circularity. Incentives such as grants and subsidies that look to lower the financial barriers for innovators would no doubt be welcomed and encourage collaboration of sustainable practices throughout the construction industry.”
Design for deconstruction and repurposing
It’s a challenge to design and construct any building but planning in detail how to have it efficiently taken apart decades in the future is something else. “We talk about it a lot,” said Holly-Mo Vyse, Senior Sustainability Consultant for Buro Happold. “It’s something that I would love to see clients do more of and it’s something we’re really trying to push. The problem with design for deconstruction is it’s a slightly newer concept, so you are asking structural engineers to design differently with a bit more thought. You’re trying to change ‘business as usual’, which is a good thing, but it can be a slightly challenging thing to do.”
A reasonable question to ask is how often does design for deconstruction get discussed and delivered with serious intent? Retail, sports facilities and multi-storey car parks are prime examples of design for deconstruction – e.g. the entire upper tiers of London’s Olympic Stadium were all built in precast concrete and designed to be disassembled.
“I think one thing is to recognise that it doesn’t necessarily need to be the entire structure and building that you design for disassembly,” said Elaine Toogood. “It’s elements of it, more of a case for design for adaptation and the most appropriate answer for the anticipated end-of-life scenario.”
It is also knowing what is possible. Structural engineers, architects and sustainability advisors need to understand the limits and what is genuinely achievable, what functions and applications can be designed in more easily. External structure may stay the same, but everything inside could – and probably will – change. It’s a case of ‘structure versus stuff’ and incentivising the whole design process. Offsite manufacture has excelled with standardised elements, platform design and kit of parts approaches, that encourage reuse, reformatting or ‘optioneering’ of the best elements.
Material passports
We know a lot about what we build today, but in 60-100 years’ time when a building could be approaching its end-of-life, how will we truly understand the building fabric and countless interior components value? The emergence of digital material passports can unlock a building’s reuse potential in forensic detail. These electronic datasets both document and maintain details about building performance and the properties of materials plus structural information and characteristics. They also record the materials’ location within the building, any physical markings or hazardous components, and are being hailed alongside environmental product declaration (EPD) and RFID tags as tools to help define a buildings circular and carbon impact. Waterman Group are presently using ‘Edenica’ a 94,000sq ft commercial office development, in London’s Holborn, as a pioneering materials passport scheme, attempting to understand the building as a ‘material bank’, to enabling future re-use of materials.
Much is made of the lessons that construction industry can learn from the automotive industry. Part of that is utilising data and understanding the value of that data to link back to the ‘material bank’ of a building. “But there’s an intellectual property aspect to this,” added Elaine Toogood. “Who owns that data? How is that going to be translated and communicated in the future and in what format? Buildings could last a lot longer than the technology that we use to share data about them.”
It may be as simple as putting a QR code on the building, or for product manufacturers to stamp products with a new mark as reusable or recyclable in a deconstruction context – what can be reused or recycled to what grade and future quality – is there a degradation?
Offsite manufacturing has many controllable processes. It is generally understood what is in each building or system that is delivered, unlike the diverse supply chain of traditional construction which could contain a huge mix of products. But there needs to be a recognition of material context, its use and longevity. As data collection becomes more sophisticated, the use of BIM and digital twins make it easier to interpret and analyse material constraints. The hope is that all building elements and materials can somehow be quantified and marked for adaptive purposes – and if this information is set to exist in an open-source cloud environment – the data has to be in an accessible and open format.
Digital material passports provide an immediacy and accessibility of information for all users. If a developer is looking at a particular site pre- or post-demolition, they can gauge what materials are becoming available and opportunities to repurpose a significant amount. “That would be advantageous,” says Holly-Mo Vyse. “Materials are expensive. We need to change how we value our materials to the point where we have to reuse them.”
Clearly a paradigm shift is required towards demolition and material reuse and its role within the wider circular and sustainability agendas. Harvesting and farming our urban areas – reclaiming our natural resources – is within our capabilities and implementing systems that enable all parts of the supply chain, from clients and developers to structural engineers and design teams needs reformatting. How this is incentivised is through better collaboration, education and valuable case studies – or just thinking it’s the right thing to do ethically and best practice. Or more probably by legislation such as the Building Safety Act and mandated design.
Design for deconstruction in the right circumstances can provide a new lease of life for old materials and critically continue to lock in carbon and remove needless waste to landfill. This is already taking place internationally. One example is The Circle House in Aarhus, Denmark, a social housing project where primarily precast concrete components have been designed to be disassembled and reused in new structures. These kinds of case studies and the learning taken from them go a long way to prove the ethos driving design for deconstruction, material longevity and circularity.
Many thanks to Aggregate Industries for hosting the roundtable event and thanks to all participants for their time and contributions to the lively discussion.
Attendees
Facilitator: Darren Richards – Managing Director, Cogent Consulting
Eoin Bailey – UK Innovation & Circular Economy Lead, Celsa UK
Leon Black – Professor of Infrastructure Materials, University of Leeds
Mark Hickingbottom – Commercial Director, Aggregate Industries
Kishor Nair – Trainee Sustainability Advisor, Powerday
Karen Ogden – Senior Marketing Business Partner, Aggregate Industries
Chloe Parmentar – Associate, Urbana
Patrick Rafferty – Environmental Sustainability & Compliance Advisor, Powerday
Elaine Toogood – Director, Architecture and Sustainable Design, Concrete Centre
Holly-Mo Vyse – Senior Sustainability Consultant, Buro Happold
For more information visit: www.aggregate.com
