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Transforming construction: Building the UK's circular economy

The pressure for the built environment to reduce carbon emissions and think long-term sustainability is increasing. This is where the Circular Economy model comes in to play. But what exactly does it entail, how can we achieve it and who needs to be involved?

A circular economy is about approaching the way we design and make things with the intention to recycle, reduce and reuse as many resources as possible. The current business model is to design and make something then throw it away – the linear model. This is neither sustainable nor desirable for the environment. In the construction industry, a circular economy encourages all in the supply chain to choose materials that can achieve a longer life cycle. That means everyone involved from the client to the architect to the product component manufacturers and engineers and contractors are all responsible for making better choices to create a circular building.

A significant part of building circular is to reduce the built environment’s impact on climate change. It’s no secret that the Paris Climate Agreement’s aim is to reduce global warming to 1.5 degrees. And in the most recent Circularity Gap Report for 2019, it’s reported that only 9% of the world is circular and “material use and carbon emissions continue on an upward trend.”

Proof is in the pudding

In a bid to get the circular economy spinning in the right direction, certification schemes have been developed, such as Cradle to Cradle Certified (C2C Certified), which is a framework based on quality assessment and innovation. Products are assessed under five criteria called quality categories: Material Health, Material Reutilisation, Renewable Energy & Carbon Management, Water Stewardship and Social Fairness. The product is then given an overall certification level, a grade, based on how many of the quality categories the product fulfils: Basic, Bronze, Silver, Gold and Platinum.

In 2017, the British Woodworking Federation did a feasibility study on cradle to cradle timber windows with C2C Certified. The windows were awarded with gold for Material Reutilisation, Renewable Energy & Carbon Management, Water Stewardship and Social Fairness. Silver was awarded for Material Health, giving an overall Silver grading for timber windows. The only reason for not achieving Gold is that only 95% of the materials used made up wood and preservatives. To get the top mark, 100% of the materials need to be assessed.

At the 2019 ASBP Awards, EcoCocon won the Product Innovation Award for its use of straw bale panels in a rural self-build. The panels are C2C Certified with a silver award, and the project was a first for using this particular system in the UK. What impressed judges most was “the combination of extremely high fabric efficiency (Passivhaus certification) achieved through the use of a range of low-impact, natural materials to create a comfortable, healthy environment.”

With the number of C2C Certified products rising, others have been inspired to raise awareness of this offering, cue the creation of Cradle to Cradle Marketplace. As a natural renewable building material, it’s unsurprising there are already a number of timber C2C Certified products available for the built environment.

Building the UK’s Circular Economy

The Vision 2040 of the European Forest-Based Sector targets material collection rates of forest-based products at 90% and for their reuse and recycling to account for 70% of all recyclable material. This idea of a circular economy would store carbon and substitute more energy-intensive materials.

In the UK, the Green Building Council UKGBC is working with its members and the wider industry to develop practical guidance which will enable organisations working in the built environment to overcome the barriers to implementing circular economy principles. 

To understand more about where we are currently and the opportunities for a circular economy within the built environment, we talked to three industry experts:

Adrian Campbell, founder and director of Changebuilding, Charlie Law, founder and director of Sustainable Construction Solutions, and Pablo van der Lugt, head of sustainability at MOSO and Accsys Technologies. Join the discussion and send us your comments here.

What is the current status of the circular economy in the built environment?

Adrian: Many of the features of the circular economy go back to other work related to Natural Capital, Biomimicry and others strands of thinking that have influenced design for a while. As the built environment is a large and complicated system we need to address issues on that scale to incentivise the system to change. Obviously one of the main levers is money, and currently we don’t value resources and the indirect environmental costs sufficiently. That may change. Therefore it’s about focusing on what we do with outputs to allow for circularity to be a more pervasive ideal.

Charlie: As it stands there has been limited take up of the circular economy in the built environment. Many see the new business models required to make the circular economy a success as too difficult. This isn’t the case in the Netherlands on projects such as Park 2020, Brummen Town Hall, Liander, and the ABN AMRO Circl building. These examples show there is a demand from some clients at a building level, therefore suppliers need to pick up on this and design components that can deliver fully circular buildings.

Pablo: We’re barely circular today. The built environment contributes to nearly half of the total material footprint - 40.6 Gton of the total 92.8Gt material footprint in 2018.

If we look at the main materials used in construction, we can see the following:


Plastics are probably perceived as the best recyclable material. However, of the 320 million tons of plastics produced worldwide, only low amounts of post-consumer plastics are recycled, even in highly industrialized regions such as Europe (26% recycled, 36% burned, 38% landfill) and USA (9% recycled, 91% discarded). If we look at the number of PVC recycling from the Vinyl plus website, we can find that compared to the 5.5 mio tons of PVC produced annually in Europe, the recycling rate lags far behind at 0.44 mio tons (less than 10% of the production rate), with a target to recycle of 0.8 mio tons by 2020. This means that the lion’s share of PVC waste (4.1 mio tons in the EU) is either burned or landfilled.


At 70-80% Recycling figures for aluminium and steel are a lot higher. However, there is not nearly enough secondary aluminium and steel material (scrap) available worldwide to meet demand and this is not expected to change in the near future. This means that of all the newly produced aluminium and steel only about 1/3 is made from recycled materials, the rest is based on virgin material. Taking into account that reserves of aluminium and iron (the main component for steel) are expected to be depleted within this century this shows that also metallic minerals will not provide the solution towards a full transition to a Circular Economy.


Because of the immense volumes of concrete being used worldwide, concrete recycling has gained momentum but mainly for reasons of cost reduction. Concrete recycling is increasing, with recycling rates between 30 and 80% in Europa and the USA, often in lower value-added applications (downcycling) such as road bedding or aggregate (up to 20%) in new concrete. This does not heavily influence CO2 emissions, as the most carbon intensive component of concrete, cement, is not recyclable and thus carbon intensive virgin cement needs to be added.  


In the EU about 1/3 of the wood is recycled into new boards or panels, about 1/3 is burnt for energy production and about 1/3 ends up in landfill. But here the story is different, as wood is non-toxic it can biodegrade (bio-cycle) or can be cleanly burnt for energy production. Plus, in the case of long-term use such as acetylated wood or CLT/Glulam, in the meantime the wood required for the application, has grown back in sustainably managed plantations.

For example, Accoya’s lifespan is usually 60+ years, while the fast growing Radiata Pine tree used to produce Accoya has grown back twice in that period. Furthermore, if the Accoya wood is than converted into Tricoya panels (lifespan 60+ years), this advantage is even higher (four times grown back during lifetime of Accoya + Tricoya).

What does circular construction look like?

Adrian: A new building system which makes and re-makes buildings with limited input (e.g. energy, water resources etc). These buildings are healthier for the users and the broader natural environment. Many of the principles are close to the ambitions we have had for many years for more sustainable buildings incorporating low-carbon, renewable products that are highly-recycled and have a long life. We need to find the market methods to make this commonplace.

Charlie: We need to consider service life optimisation, which could include longer life components such as the building skin. This should ensure ease of re-use or recycling for other components, such as floor finishes, which change with fashion trends. We need to design for maintenance ensuring products are easily accessible and potentially include maintenance as part of a service contract. We need to consider resource efficiency but not at the expense of longer life, we need to design for flexibility, deconstruction, disassembly and remanufacture. We also need to ensure we use raw materials from renewable sources wherever possible and get the best possible utilisation from the materials. For example, ensuring timber components are re-manufactured into other products several times before being turned into biomass. These products should be manufactured in controlled environments using renewable energy. We then need to look at how these products are managed over their lifetime by ensuring a suitable business model is in place to ensure they are maintained and bought back into the loop at the end of their service life (e.g. through service contracts, lease agreements, etc.)

Pablo: A true circular building is made of components of fully recyclable, non mixed technocycle materials, that can be 1 on 1 upcycled in the end of life (e.g. concrete columns), combined with building components that are fully fitting with the biocycle (e.g. prefab CLT components) that may recycled and even downcycled (particle board, bio-energy) as long as the wood used has grown back during the lifespan of the project (like Accoya from Radiata Pine). Also it is important to use as many fully non-toxic materials as possible, proven by C2C Gold / Platinum certification. Ideally these building components are leased and there is an accurate overview of the materials used in a Material Passport of the building, this way a building becomes a material bank as shown in the BAMB2020 project. In the Netherlands, Venlo City Hall and Circl Pavillion ABN AMRO bank Amsterdam WTC are showcases of a circular building project.


Which trends do you identify in your line of work?

Adrian: I’ve been working in timber design for about 10 years now following my work on Low2No in Finland where cross-laminated timber (CLT) was a major opportunity for use of local forestry and significantly lower embodied carbon design to normal methods. It’s one of the few structural materials I have come across that can be used at scale that addresses energy use in the manufacturing stage. This has taken off substantially but even though CLT has renewable production qualities, we don’t focus enough on end of life and disassembly of buildings.

Charlie: We are starting to see some component manufacturers adopting a circular approach, but these tend to be in the shorter service life applications such as carpet tiles (Desso, Interface, Shaw take back schemes), ceiling tiles (Armstrong take back scheme) and office furniture (Herman Miller remanufacture). However, they are still based on old business models where the items are repurposed into the market place, but their life cycle isn’t being tracked, so a large percentage will get lost in the system. Other industries such as textiles and technology are addressing this and we need to look for solutions for longer life products too.

What are the issues and barriers to make construction and building products circular?

Adrian: Like with sustainability, I think we need to be clear of the terms and also how to assess and certify products and buildings. Just like we have methods on supply provenance, we need more building products to demonstrate their credentials. At home, my ironing board comes with C2C certification, so why not for buildings?

Charlie: The barriers are two-fold. Firstly, there is a lack of understanding from clients on how the new business models could be adopted for construction. There is still a perceived understanding that they need to own all the materials in their building, when in fact all they need to own is the space the building provides. Everything else could be owned by someone else who provides the client with a lease agreement or service contract. This leads onto the second barrier - the new business model solutions are not readily available to the client. It may mean a shift in the way buildings are procured, with the component manufacturers taking a much more prominent role in the supply chain.

What circular solutions are already out there in the built environment?

Adrian: I think initiatives like Buildings as Material Banks (BAMB) and the emerging digitisation of construction, including Digital Twin, allows products to achieve the necessary scale to influence the market. We have many digital platforms for linking buyers with sellers, so those sorts of technologies will help. My understanding is there is about a ten-fold difference in input costs for mass timber to output value at end of life as biomass. That’s an opportunity to make new buildings cheaper and retain that pool of sequestered carbon in use. But to do that we need to include disassembly as part of the original design ideals. The Circular Building by Arup was a useful exploration of the ideas and demonstrated many of the overall issues including internal finishes and building services.

Charlie: Manufacturers such as Desso, Interface, and Shaw all have take-back schemes in place for carpet tiles, and Armstrong has a similar system for ceiling tiles. Herman Miller is designing its office furniture to allow for better maintenance and remanufacture. The timber industry has a good system in place for the reuse of waste timber, with around 17% making its way back into panel board manufacture, but this needs to be improved significantly. Just because timber is a renewable resource, it doesn’t mean we shouldn’t be efficient with its use! However, there are significant opportunities for component manufacturers to develop circular solutions that could be offered to the market for every building component. If done correctly this will allow them to maintain control of their future material inputs, which has both cost and material security benefits to the manufacturer.

How do you see a circular economy being achieved in the built environment?

Adrian: I’d like to see environmental impacts of resources accounted for more explicitly. That will start to alter the economics. I’d also like to see more take up on efficient manufacturing of buildings through Design for Manufacture and Assembly (DfMA) and its advantages but adding on disassembly - DfMA+D. Then, if we identify issues relating to the health of products for building users and our shared environment, we might get closer to a beneficial system overall. There are roles for everyone, and we need to breakdown some of these typical sub groups as they reinforce the inability to change. The more progressive manufacturers are proactive about improving and limiting their future risks. That could be replicated by investigating how they re-make products or re-purpose them.

Charlie: We need component manufacturers to take the lead and develop circular solutions that could be offered to the market for every building component. We need to educate clients, developers and cost consultants that not owning the components in their building is a good thing, and that by allowing value to be maintained in the components there is less chance of their building becoming a future liability. I see the contractor as the facilitator in this process able to offer circular solutions to clients and ensure they are incorporated in the right way. Architects and engineers will need to understand how the new wave of circular components will fit within a circular building to ensure they are easily maintained where required, and able to be easily removed at the end of their life for reuse or remanufacture. The Supply Chain Sustainability School has some free e-learning resources online and also runs workshops on implementing the circular economy. Partners of the school can host a workshop for their supply chain to attend free of charge. Companies in Scotland can access help through Zero Waste Scotland.

Pablo: We have to be realistic. The net area of forests in the Northern hemisphere is actually increasing, albeit slowly (e.g. in Europe the net forest area increases with 0.4 million hectares a year). Fully switching to wood or other bio-based materials is not yet an option. First, production capacity needs to be increased by investing in new, sustainably managed production forests worldwide. This will also help capture more carbon for climate change mitigation. Assuming that political support in favour of a bio-based economy will grow as a result of increasing material scarcity and possibly carbon taxing, where should the focus of the application of wood and other bio-based materials lie? Because of the sheer volume, substituting concrete and bricks in bearing constructions would certainly be beneficial and in that light the increasing interest in timber-frame housing is promising. Furthermore, recent large building projects with a main bearing structure of wood show great potential, also for reducing CO2 emissions. However, the reality is that the main components for concrete production (sand, gravel, cement) are abundantly available in the world and concrete recycling is increasing. Therefore, unless there will be an energy crisis (a lot of energy is required to produce concrete), concrete is expected to remain very price-competitive and therefore continue to be the most dominant player in the building industry the coming decades and possibly centuries. Because of the limited reserves and high carbon footprint, another interesting substitution market for wood and other bio-based materials seems to be metals (aluminium, steel) and plastics (PVC, but also PE and insulation materials such as PUR), but only if they can meet the high technical performance requirements, e.g. Accoya window frame instead of PVC / aluminium window frame.

What next?

This is the start of a longer discussion on creating a circular economy in the built environment and what we can do to advance this in practice - from planting trees to design, de-construction and re-construction / re-use of materials and entire buildings. Send us your question, comment or case study to help advance the debate and make a circular economy happen.

Learn more about the discussion around techno-cycle and bio-cycle solutions.

Find a selection of circular wood products here.

Read the BRE case study on Design for Deconstruction and learn about their CE guidance.

Discover MAKAR's take on delivering circular buildings.

Digest the Circular Gap report.

Image: Carbon Dynamic

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