The Circular Economy in Construction
On the 14th October 2020, the Mayor of London’s office published a document to help property developers and architects get to grips with designing for a circular economy. The document, entitled ‘Design for a Circular Economy’, is a primer that will help designers prepare for London’s transition to a circular economy, the ambition for which is set out by the Mayor in the draft London Plan and Environment Strategy.
The release of this document should be a wake up call to all designers, highlighting the need to transform the way we rapidly consume and dispose of resources in order to protect the fragile ecosystems that support life on earth.
Last month we delivered a talk about the circular economy in construction at a Future Economy Network event in Weston-Super-Mare.
In order to explain the key principles of the circular economy, we started the talk by zooming right out, to an image of our planet Earth. Its only by doing this, that we can really start to grasp the concept of our fragile planet as an eco system; perfectly balanced to continually regenerate. The concept of waste doesn’t exist in nature – waste from one natural process always becomes food or fuel for other processes.
According to studies done by Bioregional, we are currently using 1.7 planets worth of resources globally. This means it now takes the earth 1 year and 8 months to regenerate the resources we use and absorb the waste we produce each year.
Clearly, we can’t keep on plundering the earth’s resources in this way, using them and then throwing them away – because we’re going to run out of resource very quickly and destroy our life support system in the process.
The construction industry is a huge contributor to both waste and the mining of raw materials. Buildings are stripped out and demolished at astonishing rates, while new buildings are being made from virgin materials with little regard for the impact this has on fragile eco systems or thought about what happens to the building beyond its construction.
Put in perspective, the built environment demands around 47% of the worlds extracted materials and waste from demolition and construction represents 60% of the UK waste stream.
One of the reasons the construction industry produces so much waste is that traditionally contractors over order materials to ensure that trades are kept busy. Its more expensive to pay them to wait around for material to arrive to site, than it is to over order by 10-15%
So for every 6-7 houses built, one house worth of material goes to landfill. This is a totally shocking waste or resource.
Waste materials from site are often hard to reuse or recycle – especially if they are contaminated with waste from wet trades; plaster and concrete poured into a skip will turn all the waste into an amorphous lump that no longer has any value or ability to be re-used.
Recycling has become more prevalent in the industry, but current practices focus on downcycling, meaning they end up as lower grade products. So concrete becomes aggregate and materials such as plastics and aluminium get downgraded each time they’re recycled until they end up in landfill.
Instead, we need to find a way to keep materials in repetitive loops, maintaining them at their highest possible intrinsic value.
One of the most important concepts of the circular economy is that materials can be designed to differentiate between the Biosphere and the Technosphere and become nutrients forever.
For example, the ‘waste’ from a bio-based material becomes nutrition for plants or animals at the end of its life. A timber beam might be used in a building structure, then re-used as a non-structural element such as a table, then formed into fibreboard before being composted to generate biogas.
Technical nutrients include metals, plastics and other materials not continuously made by the bioshphere. Instead of these materials becoming waste in landfill, they can become ‘food’ for another product, and that in turn becomes ‘food’ for another – endlessly.
A circular economy is about fundamentally designing out the concept of waste.
Reusing discarded materials is difficult to do. There are currently no provisions for insurance and guarantee of recovered material and we don’t have the legislation or networks in the UK to do it easily.
There are however architects who are starting to explore re-use of materials, and one idea being developed to enable this are ‘material passports’. These give each component of the building an identity to prevent it ever becoming waste.
If every material and component in a building was given an identity and its potential for re-use was understood, the building would become a bank of components that had a potential future life and a known value beyond demolition spoil.
To implement wide spread re-use of materials in the UK, we need a central hub where information can be stored and used materials can be bought and sold. There are sharing platforms in Europe, such as Madaster, which allows designers and others along the construction chain to upload BIM data relating to a building. The platform then generates passports which hold data about re-use and potential value.
This is not available in the UK yet. However, construction and demolition businesses in the UK are starting to recognise the value of materials in buildings, with companies like Globechain providing an online marketplace for reuse of materials.
We feel there is a role for both industry and government in making material passports standard in construction. You need to get some people to lead the way by implementing this approach, in partnership with the public sector, so policymakers can see there is both the will to do so from market leaders and a demonstrable economic benefit.
This leads us nicely on to the idea of buildings as material banks; the idea that buildings store valuable resources for future use.
In order to think of buildings in this way, we need to start designing for disassembly and recoverability. This requires us to think very carefully at design stage about how the materials and components can be dismantled. Demountable fixing methods are key to re-use, as is the need to avoide resins, adhesives or coating on elements.
ABN Amro Bank designed their new flagship office using circular principles. They know that their office will be out of date in 25 years and will need to be replaced, so they designed it with disassembly in mind. The bank realised that if they saw the building as a material store, it would be a financial asset at the end of its life, rather than a deficit to be demolished and got rid of.
It shows how a circular building costs less to build with fewer resources and wastage at construction stage, it retains its value by being easily adaptable and at the end of its life, components have retained value for re-use.
A conventional construction costs more to build and continues to loose value through its life, leaving the building owner in a financial deficit at the end of the buildings life when it has to be disposed of.
Designing buildings in layers recognises that different elements of the building have different lifespans and should therefore be independent to allow different layers to be peeled off and replaced or salvaged without damage to adjacent longer lasting layers.
Short lifespan components include internal finishes and furniture that might last between 3-5 years The materials used for these items need to match their lifespan and be designed for disassembly and return to the manufacturer for re-use.
Medium term components include internal partitions, ceilings and floors finishes that last between 5-10 years. These should be designed for reconfiguration, using modular systems.
Longer lifespan components include building services that last 20-30 years. These should be designed for maintenance, replaceability and remanufacture.
The longest lifespan components include the sub structure, structure, floors and fabric that could last between 30-300 years. These need to be designed to be long life, loose fit and adaptable to different uses.
For products with a shorter lifespan, leasing options allow companies to take corporate responsibility for the repair, maintenance and end of life strategy of their products.
Traditionally companies focus on sales – producing products for the lowest possible price which customers are then responsible for maintaining, repairing and disposing of.
Service models allow customers and manufacturers to build up long term relationships, with customers purchasing performance rather than products. This encourages companies to invest in designing durable products that have the ability to be deconstructed and remanufactured. Examples of this include Phillips, who lease lighting and Interface, who lease carpet tiles.
The circular economy is fast rising up the business and political agenda. Although the UK still has someway to go, policy such as that incorporated into the draft London Plan, will start to shift the way designers and developers think about resource and waste.
As a practice we will continue to engage with our clients, test solutions with industry partners and deliver projects that think about resource differently – making both environmental and economic sense.