The Mayor has set ambitious targets for London to be a zero-carbon city by 2030. If we are to achieve carbon neutrality our priorities must include retaining buildings and infrastructure while making them more environmentally sustainable and replacing the end-of-life concept with re-use, re-purpose and recycle.

This NLA report looks at strategies, initiatives and projects that are pushing the boundaries to build a circular city.

By Peter Murray, Co-founder, NLA

The London Plan, with its focus on good growth, is committed to addressing the city's need to reduce its carbon footprint with sections on active travel targets, urban greening, sustainable drainage and the circular economy. The last is probably the most complex to deliver in an industry that has traditionally been heavily reliant on extracted resources. Now designers and contractors must ponder how demolition materials can be reused or recycled and how components and products can be disassembled and reused at the end of their useful life. They need to look at managing waste on site and consider storage space to support recycling and reuse.

But as yet, London has no functioning second-hand materials market that is easy to procure from. It requires a radical change in the way we think about constructing, equipping, using, maintaining, altering, and renewing our built environment. It needs a new economic model that moves away from our current linear economy, where materials are mined, manufactured, used, and thrown away, to an economy where resources are kept in use, and their value is retained.

But who takes the lead? Can existing suppliers and merchants adapt and change their business model? Will design teams respond?

This report features Danish architect Anders Lendager'sResourceRows housing scheme in Ørestad, Copenhagen, described as the world's first circular economy building. It uses upcycled bricks and waste wood, a recycled concrete beam as a bridge, and old windows and waste wood on rooftop community garden huts.

To deliver his circular projects, Lendager has set up several building materials companies re-making plastic, bricks, wood, and windows. Resource Rows did not cost more to build than traditional construction and is one of the most popular rental projects in Ørestad. In fact people rather like it: Lendager talks of a new aesthetic that celebrates upcycling and how the narratives of rescued materials connect with the occupiers. He believes that architects should be master builders, not color pickers.

In the UK, the Alliance for Sustainable Building Products has produced a toolkit for steel reuse and a number of featured projects are using second-hand steel and raised flooring. Seratech, established by staff and researchers at Imperial College, is working on cement substitutes that capture industrial CO2 emissions directly from flues and produce a carbon-negative cement replacement material. But it is not yet in commercial production. The idea that buildings and infrastructure should be designed to have long lifespans and be easily adaptable for future needs has been around for a long time. The concept of long life, loose fit was first promoted by RIBA President Alex Gordon back in 1974. It was popularised by Stewart Brand in his book 'How buildings learn.' If you google architects who use flexibility and adaptability in their lexicon, you get BIG, Renzo Piano, Foster + Partners, DillerScofidio + Renfro, AHMM, Make, and Lifschutz Davidson (LifschutzDavidson Sandilands edited an excellent issue of Architectural Design on the subject). However, it is still challenging to deliver unless developers, too, have bought into the concept.

Will the existing materials industry adapt, or will they feel it threatens their business? The circular economy could offer significant economic benefits to the construction industry. By embracing circular practices, companies can tap into new business models, such as leasing and sharing, to provide ongoing revenue streams. Moreover, it's a growth market, presenting opportunities for innovative companies to develop and offer sustainable solutions.

The circular economy should encourage collaboration among stakeholders—architects, contractors, developers, and materials suppliers. Cities are the mines from which building resources can be gathered with materials from existing buildings deconstructed and recovered for reuse, materials that cannot be directly reused, recycled, or upcycled and converted into new products or materials. Procurement processes should prioritize selecting durable and recyclable materials, while BIM can enable better tracking, documentation, and information sharing about materials, components, and systems.

5 Foreword
7 Executive Summary
10 Building a renewable London
38 Viewpoints
48 Project Showcase
98 Endnotes and further reading
99 Acknowledgements

Published July 2023
102 pages