Embracing principles of the circular economy could bring a number of benefits to the built environment. Buildings are regularly stripped out and torn down, with new buildings frequently constructed from hard-won raw materials. Given the construction industry is responsible for around a third of total waste generated in the EU, the built environment is a prime candidate for applying a circular economy approach. Renewable Matter has discussed the issue with David Cheshire, Sustainability Director at the infrastructure firm AECOM, and author of the book "Building Revolution" (second edition is coming out soon) one of the first publications that discusses a set of circular economy principles specifically for the built environment. Cheshire has also launched recently a new tool with the University of Sheffield, Regenerate.

I would like to start by focusing on what is means for you circular buildings.
The idea is to retain the value of the buildings in terms of the resources in the building as long as we can, hopefully indefinitely. Retaining, refurbishing and refitting existing buildings, is the priority. And if we're building new and we design buildings, that can be around for a long time, do not design buildings that have just one use or are restricted in terms of their adaptability.
First rule is design for disassembly. Assuming that all the buildings will have an end of life at some point, we can think how to disassemble bits of building, remanufacture those bits, and remanufacture components. As a last resort, we can ensure that the components and materials enable recycling or for returning to the biosphere, if biological materials have been used. We have to design buildings in layers. You have to be able to peel off different layers of the building so you can refurbish and keep it going for longer and reclaim the bits that you're peeling off, making the buildings more adaptable.
Second, designing out waste. We need buildings to be as lean as possible in terms of the resources they use (given we plunder major resources to build) and then select the right materials that fit the lifespan and the quality of the product.
Third: different business models. Rather than ownership pay-per-use models are preferable. Mitsubishi is doing with lifts, where tenants pay for performance. This way you are not paying any capital cost, just paying operational costs. In fact, building owners will usually enter into a contract with a lift operator anyway. So why not going directly to pay for the use of material and services?

After your book has been published, did you actually see a transformation in the approach of building construction in UK?
It's still very early in the journey. But after the book came out in 2016 the Greater London Authority published a new regional spatial strategy for the whole of London that included circular economy as a new policy for the first-time. That requires that all new buildings include a circular economy statement. Both Scotland and in Wales, they do have circular economy policies built into their development policy. There are some pockets of change and some exciting new case studies and innovations.

I was really struck by the concept of adaptability...
Looking back at buildings that have survived for 100 years or more we asked: what are the common aspects of these buildings that are making them more adaptable? One: very rectangular form. That helps with keeping clean, simple floor layouts for a variety of uses. It also means that they can be extended both upwards and sideways more easily than a complex-shape building. Second: positioning of cores by ensuring that stairs or lifts are well positioned, have extra space, and don't need to be moved for new uses. Third: Good use of light. In the UK, there's lots of Victorian warehouses with good glazing ratios (30%) that can be easily reused. All buildings must have these elements if we want to adapt them to new use.

You launched a new tool to build circular building, with the University of Sheffield, Regenerate. What is it?
It is a really early-stage decision tool. Really. It's a similar process to the one that the Great London Authority asks for new constructions. It asks questions like: is there an existing building on the site? can you refurbish it? Can you reclaim the components out of the building? The goal is getting people to start to think from a much more circular perspective. Regenerate consists of a series of Circularity Criteria (CCs), which are split into four categories: design for adaptability; design for deconstruction; circular materials; and resource efficiency. These criteria are then applied to the core building layers: site, structure, skin, services and space. These criteria act both as prompts for design teams to consider if that CC could be applied beneficially to their building, and as a simplified measure of which CCs have been achieved within a building.
Regenerate is best used to embed circularity at the inception of design, although it can also be used at later stages, and reapplied as a design evolves to explore how building circularity has changed as the design has progressed, and the project is completed.

Is it complex?
It doesn't need lots of data or information to fill it in. It's more trying to get you to think of those early stage strategic decisions that will hopefully drive you down a more circular route. We want to avoid two dangers. The first is that people that reclaimed some floor tiles in one room claim that their building is circular. We have to avoid false circularity and our tool somehow helps define a circular building. Second: data-hungry calculations. These aren't really helpful at early stage; you should keep detailed embodied carbon calculations for later design stages.
We just launched Regenerate at the beginning of March. We invited about fifteen of our clients to stress test it for us and they really liked it. We are getting 3-4 requests every day since then and lots of positive feedback. Soon there will be a on-line version of the tool. I believe it can be use anywhere.