Four ways you can embrace the circular economy today

The launch of the UK Net Zero Carbon Buildings Standard at the end of October was significant for many reasons, not least that it’s pretty much the first time that representatives from most of the UK construction industry have come together to agree on what ‘good’ looks like. This sends a positive message to the UK government – ‘work with us, we know how to meet those 2050 net zero carbon targets’, while simultaneously creating a huge commercial and creative opportunity for architects well versed in low carbon construction techniques. This could result in the long-awaited inclusion of ‘Part Z’ in the Building Regulations. With embodied carbon recognised as part of the UK’s measurable carbon budget, a budget that must tumble down by 78% by 2035, we will quickly get our heads around the fact that the construction sector has to dramatically reduce its consumption of raw materials (currently running 50% of all raw materials mined and harvested every year) and in the case of the UK construction sector, dramatically reduce its gigantic waste stream that represents 63% of all our nation’s waste, compared to 35-45% in Europe.

If the reduction of consumption and waste generation is not reduced, we cannot go anywhere near meeting the demands of the Standard which recognises that humans need to keep the planet’s average temperature rise to within 1.5°. And so, with these ambitions in mind, I have described below four key circular economy ‘moves’ architects can make to enable their construction projects to meet these ambitious low carbon targets. The projects I discuss below are taken from the second edition of my book The Re-Use Atlas: a designer’s guide towards a circular economy published by RIBA. This new edition includes 40 case studies of building developments from across the UK and Europe that employ the systems change required to turn wasteful linear systems into circular economies, that is designing out waste – where waste from one system is a resource for another, saves money, creates new jobs and reduces the burden on the natural world to provide us with raw materials.

1. Obtaining a new warranty for second-hand curtain walling At No1 Triton Square Arup put together a complete design team of architects and engineers, including its in-house Life Cycle Assessment (LCA) team, which benchmarked embodied-carbon emissions against current best practise data for newbuild developments from Real Estate Environmental Benchmark (REEB). Much of the original building was either kept on site, or dismantled, upgraded and reinstalled. Arup states that it ‘chipped away at every aspect to save carbon, cut waste and deliver the best working environment possible’. The firm describes this approach as one of ‘marginal gains ... like Olympic athletes seeking major performance gains through small incremental improvements across every possible area’. Arup reconnected with many of the original suppliers. This included Scheldebouw, who supplied the glazed facade system. Although it was 19 years later, it was very happy to carefully remove over 3,500m² of the curtain wall system, comprising over 25,000 separate parts, and take it to a temporary workshop about 30 miles away from the site. Here it was cleaned up, reconditioned and reinstalled on the original building. Crucially, the facade supplier gave its refurbished product the same warranty that a new system would have. By doing this, it has proved that reuse is viable in the competitive world of commercial office building. Arup claims that the reuse of the glass facade alone saved 2,400t of CO₂ compared to using a new facade. In addition, reusing the existing structure (it was also added to and upgraded in parts) and fabric – which included 3,300m² of limestone, 35,000 tonnes of concrete and 1,877 tonnes of steel – accounted for 45% of the total carbon saving for the project.

2. Re-using former ‘Cat A’ fittings The story of how the Entopia Building came about is worth including for numerous reasons – it’s a ‘deep retrofit’ of a 1920s former telephone exchange building in Cambridge, situated in a conservation area, with an enlightened client, and a design and delivery team with an enviable track record of delivering authentic low carbon architecture projects. However, perhaps the most interesting, challenging, and potentially most impactful feature of this project is the reuse of 350 second-hand LED lights salvaged from another refurbishment project the main contractor (ISG) was working on. The lights were part of a temporary ‘Cat A’ fit out for a commercial office building in London. It is currently common practice for landlords to invest in a temporary ‘Cat A’ fitout to attract potential tenants. Once lease agreements are signed most tenants will then rip out the ‘Cat A’ fixtures and fittings, replacing them with the branded interiors they require. This practice creates huge and very pointless waste streams. In December 2022 the British Council for Offices (BCO) recommended that ‘Cat A’ is eliminated from office fitout unless specified by the incoming occupiers. It also speculated that virtual reality could be used as a zero-resource alternative to a wasteful ‘Cat A’ fitout to showcase the potential of office space. ISG, in partnership with Collecteco, was able to locate and convince the original LED supplier to inspect its previously sold fittings and honour the remaining portion of the original warranty. The lights were originally set within a ceiling system but were reused sitting proud under a soffit with additional luminaires providing up lighting. This move gained the project a BREEAM innovation credit.

3. Developing a market for ‘pre-loved’ modular systems.  The Modular Campus at Canada Water by Hawkins\Brown Architects shows how modular construction systems allow for future deconstruction and reuse. MMC system used for Phase 1 comprised 60% ‘pre-loved’ units. Phase 2 comprises 100% ‘pre-loved’ units. This project encourages suppliers to reuse their products. Phase 1 of TEDI-London by Hawkins\ Brown is a temporary college building comprising just 41 prefabricated lightweight steel framed modules clad with beautiful larch timber that is meticulously fixed to these off the shelf modules normally used as site accommodation. It was handed over to its users only nine months after the lease was signed on the land – which is incredibly quick for a 1,400m² academic building. It has planning approval for 10 years with options at the end of its first life to be dismantled and returned to Premier Modular which now has a platform selling ‘pre-loved’ versions of its modular systems and components that include the structural modules (including floors), windows and doors, internal fixtures and fittings and all interior ceilings windows, doors and even the MEP systems.  For the second phase of the Modular Campus Hawkins\ Brown prioritised the use of ‘pre-loved’ modular products that include floor and ceiling panels, the four corner posts and wall panels as well as the modular steel frame. It is envisaged that 96% of Phase 2, which numbers 104 modules, will be ‘pre-loved’. In addition, the project incorporates Premier Modular’s standard details, including standard window openings, to increase the likelihood of finding second-hand components. Because of this commitment to re-use, the buildings at TEDI are consuming a lot less new material than normal.

4. Architects construct new school buildings out of the deconstructed materials of the old school buildings. The Lendager Group has recently completed the Svanen Kindergarten in Gladsaxe, near Copenhagen. Lendager claim that it has ‘the largest percentage of reused/upcycled materials in Denmark’.  This project uses deconstructed material from the old school buildings to help create new kindergarten buildings on the land adjacent the original school. Unfortunately, the existing buildings were in such a bad state of repair that refurbishment was deemed inappropriate. In 2016, the Gladsaxe Municipality commissioned engineer Niras to undertake a detailed resource map of the existing school buildings with a view to determining the amount of material and componentry worth salvaging for the newbuild project. The client’s ambition was to reuse as much material as possible from the old school. Intriguingly, one of the reasons for doing this was to keep hold of some of the social histories imbued within these materials. Lendager’s response was to create a new kindergarten building, completed in 2023, that reads as a collection of separate but linked buildings dressed in a series of different material finishes – brick, clay tile, timber and aluminium – much of which once resided on the old school. The process of deconstruction, material selection, cleaning, storing and reuse was managed efficiently on the site, which had the space to deal with these unusual processes. One element of the old school building that is very apparent in the new kindergarten is the new orangery foyer, formed by six salvaged timber trusses that have been slightly altered to fit their new 21st-century role, and strengthened with some steel brackets and ties. In total, 27 trusses were removed in their whole state, with the others cut down. Due to fire regulations (60 minutes rating required) only six trusses were reused as trusses. However, the rest of the timber was either used within the new buildings or stored on site for the school to use in future shed and playground projects. Other surplus materials were collected by the deconstruction company, Tscherning, for use in its new headquarters building, which is under construction.

One can now argue that there is significant understanding within our industry that demands an approach to the development of the built environment supporting circular economy practices, whether that is adaptive re-use, de-constructing buildings instead of demolishing them, or designing new buildings as material banks for future buildings. This is underlined by an increasing number of circular economy road maps/guides commissioned by cities and towns across the UK, together with governments in Wales and Scotland.  As The Re-Use Atlas documents in detail, these national and regional guides are already positively affecting recently commissioned projects, and they are only guides. Just think of how transformative the addition of climate literate legislation will be. Are you ready?

Duncan Baker-Brown  is an architect, academic and climate activist and founder of BakerBrown Studio. He is author of The Re-Use Atlas published in September 2024 by the RIBA and co-editor of The Pedagogies of Re-Use published by Routledge