13 May 2022

Circularity in practice – optimising the finite


Photo courtesy of Heyne Tillett Steel

Author: Oliver Hall, Make Architects

One of the most-quoted statistics on the impact of embodied carbon in the built environment is that 80 percent of the buildings we’ll need by 2050 already exist. This provides a clear rationale for the reuse and retrofit of existing buildings; however, as the redevelopment of city office buildings continues at a rapid pace, there are many examples where keeping existing buildings isn’t seen as a viable option – whether that’s for financial, structural or various other reasons. This conflict leads to fierce debate and friction between carbon and commercial aspirations and priorities.

The principles of circularity may provide a resolution to this debate. When viewed from a circular mindset, existing buildings have much to offer, and by designing adaptable, demountable structures, we have an opportunity to sustainably extend the lifespan of buildings and their materials.

To further understand and explore these opportunities, BCO Nextgen brought together a panel of industry experts working at the forefront of circularity. These included Rachel Hoolahan (Sustainability Coordinator at Orms), Steve Gilchrist (Project Director at Grosvenor), Andrea Charlson (Commercial Manager and Built Environment Lead at ReLondon), and Laura Batty (Structural Engineer and Associate at Heyne Tillett Steel).


Circular design at all scales

Rachel Hoolahan set the challenge at Orms to aim for at least one deep sustainability assignment on each project. This design-research mentality is leading to innovation that unlocks circular economy opportunities. During the panel discussions, she raised the challenges and questions brought to light during the redevelopment of 160 Old Street, a former Royal Mail sorting office.

The project achieved a 70 percent uplift in net internal area through a reconfiguration and extension, while retaining 76 percent of the existing structure, saving nearly 3,000 tons of COemissions. The key challenge, however, was ensuring the additional floorplates were flexible and of a high-quality, as expected in a new building. Although the retention and extension of the existing structure had the biggest carbon savings, it was in the selection, specification and design of new elements that needed the most challenging. Hoolahan gave the example of the ceramic sinks in the washrooms, which could be “easily uninstalled, disassembled and reused in the future, [while opening] up the opportunity to source reused sinks as the initial specification.”

While this is just one example of a ‘deep assignment’, by implementing this circular mindset both at a large and small scale, the materials and the building are ensured for long-term, flexible and sustainable use. 


Developers driving innovation

Grosvenor has been exploring circularity innovations across several projects, both in terms of practical applications and the long-term implications of them. They see materials reuse as an opportunity to balance their materials across a range of sites. But as project director Steve Gilchrist explained, circularity can be a wide-ranging topic, so you need to be focused to create any meaningful change.

He explained that during a recent project, in collaboration with Orms, Grosvenor paused the design to slow down and focus on the long-term impact of the building. Steve said, “We want [the design team] to learn about the building now, [and] think about how things could be done in the future,” before rushing into the design. This thinking, combined with Grosvenor’s ambition to explore the full process of implementing circularity, meant the design team could engage with detailed building surveys and thoroughly understand the materials within the building, and whether they could be reused. The team also worked with lawyers on warranties, to ensure these ideas could be implemented in a commercially sustainable way.

In demonstrating to supply chains that reusing materials from existing building stock can be viable, Grosvenor are paving the way for more detailed circular material models in future.


Creating a model for circularity

While the private sector is making tremendous progress, the public sector is critical to the successful adoption of circular economy strategies across the industry. ReLondon, a partnership between the Mayor of London and the London boroughs, is on a mission to revolutionise London’s relationship with products and waste. As Andrea Charlson put it, ReLondon are “helping London waste less, reuse, recycle, repair and share more.”

One of ReLondon’s focus areas is the inclusion of circularity in The London Plan. The policy around reducing waste and supporting a circular economy has four key elements; a requirement to collaborate, promote a more circular economy, produce innovation, and adhere to targets around waste diversion from landfill and reuse. However, the most significant element for most large developments is the requirement for referrable schemes to submit a circular economy statement as part of the planning process. Two of the most interesting components of embedding circularity in the planning process is the need for a pre-demolition audit – if the site’s being demolished or redevelopment – and the post-construction requirements that show how a building can be adapted and reused in future. Where this is implemented, it is expected that we’ll see a real-world reduction in the use of virgin materials across the whole life of a project, leading to a reduced carbon budget.

ReLondon is part of a consortium of 31 organisations across 4 cities (London, Copenhagen, Hamburg and the Helsinki region) who are working together on the Horizon 2020-funded ‘Circular Construction in Regenerative Cities’ (CIRCuIT) project. Through the project, they are aiming to reduce the yearly consumption of virgin raw materials by 20% in new construction, and show cost savings of 15% – something that can only be achieved through collaboration.  ReLondon are also trying to improve the quantity of data available, and the accessibility of existing data, while providing tools to access it – all of which will help ReLondon, and fellow organisations, achieve this collective goal of reducing waste and carbon.

By pushing for policy change in the public sector, ReLondon are steering the local industry, and indeed a global city, in the direction of circularity.


Engrained disassembly

While the opportunity and scalability of circularity offers the potential to revolutionise the construction industry and reduce our impact on finite resources, there are also easy wins that all projects can, and must, start actioning. Not every project will have a reusable structure, and not every project team has access to a materials bank, but through early design decisions, we can make new buildings easier to adapt, reuse and disassemble in the future.

Laura Batty runs the internal research and development department at Heyne Tillett Steel, where they’ve been exploring the principles of circular design and disassembly on various projects, including their new offices at 16 Chart Street. She says the opportunity to extend the lifespan of the things we use is important, and by creating structures that are “designed to be disassembled and reused at a higher possible value, [we are] eliminating waste and pollution, avoiding things being designed to be thrown away, and designing instead to facilitate reappropriation and recycling.” Designing structures that can be disassembled using bolted connections and exposed steelwork, for example, makes the process of disassembly more achievable when the building’s functional life is over.

By factoring the end of a building’s life into its design, we can redefine the life cycles of buildings and establish a framework for a circular industry.



It’s clear from the panellists that circularity cannot be achieved in isolation – it needs to be a collaborative process, between internal teams, developers and designers, and the public and private sectors. Circularity looks set to revolutionise the workplace life cycle and reduce the sector’s impact on the environment, but only if everyone involved is willing to move beyond the standard models of design, procurement and occupation, and shift towards closing the loop instead.  

We wish to thank our panellists for their unique, expert perspectives on the challenges and opportunities of circularity in practice. To listen to the full discussion, click the link here.