Steel reuse promises big wins for circularity and carbon reduction in construction, but for now, projects are being driven by a small number of pioneers.
The idea of circularity is gaining fresh urgency in light of the climate crisis and is already underpinned by initiatives such as the European Commission's 2020 circular economy action plan, considered a critical pathway to achieving overarching net zero ambitions.
The UK Green Building Council (UKGBC) defines circularity as a system that "prioritises the reuse of materials, preventing the over-extraction of natural resources and the number of usable materials that end up in landfill".
According to the UKGBC, 99% of all UK structural steel sections are currently recovered, with 86% sent for recycling – typically electric arc furnace (EAF) recycling – and 13% for reuse.
There are strong arguments in favour of raising the latter percentage; the Steel Construction Institute (SCI) protocol for reusing structural steel describes structural steel sections as "an obvious candidate for reclamation and reuse".
Steel reuse offers up to 97% embodied carbon savings compared to using new steel and is 10 times less carbon intensive than recycling, according to not-for-profit organisation the Alliance for Sustainable Building Products (ASBP).
Steel reuse promises big wins for circularity and carbon reduction in construction, but for now, projects are being driven by a small number of pioneers.
The idea of circularity is gaining fresh urgency in light of the climate crisis and is already underpinned by initiatives such as the European Commission's 2020 circular economy action plan, considered a critical pathway to achieving overarching net zero ambitions.
The UK Green Building Council (UKGBC) defines circularity as a system that "prioritises the reuse of materials, preventing the over-extraction of natural resources and the number of usable materials that end up in landfill".
According to the UKGBC, 99% of all UK structural steel sections are currently recovered, with 86% sent for recycling – typically electric arc furnace (EAF) recycling – and 13% for reuse.
There are strong arguments in favour of raising the latter percentage; the Steel Construction Institute (SCI) protocol for reusing structural steel describes structural steel sections as "an obvious candidate for reclamation and reuse".
Steel reuse offers up to 97% embodied carbon savings compared to using new steel and is 10 times less carbon intensive than recycling, according to not-for-profit organisation the Alliance for Sustainable Building Products (ASBP).
However, ASBP also states that "the reuse of steel is minimal despite the apparent environmental, carbon and circular economy benefits".
This is despite growing interest in the commercial value of reclaimed steel among pivotal stakeholders including the UK's two principal steel fabricators, EMR and Cleveland Steel & Tubes.
Experts spoken to by NCE say factors behind slow uptake of steel reuse include design and engineering complexity and challenges in establishing a supply chain.
Pioneering projects
In the face of such hurdles, a handful of consultants, contractors and clients are taking the lead on steel reuse projects. Many of these are in London, where the Greater London Authority (GLA) has implemented Policy SI 2 in the London Plan (2020), which requires large-scale developments to calculate embodied carbon and whole life-cycle carbon emissions.
One project – delivered by Civic Engineers and Webb Yates Engineers under developer Fore Partnership – recently won the British Construction Industry Award (BCIA) 2024 Carbon Net Zero Initiative of the Year award.
It comprises an "urban mining" scheme to extract 40t of 1930s steel from the former House of Fraser department store at 318 Oxford Street and reuse it at Fore's low carbon office retrofit at Tower Bridge, TBC.London.
According to Civic Engineers director Gareth Atkinson, the scheme came about due to an alliance between "two likeminded practices who are forward-thinking in terms of sustainability" and "a client who was dogged enough to also want to make it happen".
Also seen as a milestone in steel reuse is the 2 Aldermanbury Square project, driven by property company Great Portland Estates (GPE).
It involved the demolition of the existing building at 55 Basinghall Street (City Place House) – a 10-storey steel-framed structure with two below-ground levels – to enable the construction of 30,000m2 of new office space.
Keltbray was contracted to the scheme to carry out tasks including the removal of non-load-bearing elements while preserving the building's structural integrity, structural demolition and enabling works.
Keltbray group steelwork operations manager Scott De La Fuente says a key achievement for the project was the opportunity to salvage 1800t of the existing steel frame for reuse rather than recycling.
Also in London, Elliott Wood is working on 180 Piccadilly, 6,205.9m2 of workspaces over seven floors, also being developed by GPE and using City Place House as a "donor building".
"To our knowledge it's the biggest steel reuse project in the UK at the moment," says Elliott Wood associate director Gemima Walker, confirming that the proposed scheme is sourcing nearly 450t of reclaimed steel.
Design and engineering
Methodologies for harvesting and reusing steel are emerging and evolving. On 318 Oxford Street, Atkinson confirms that Civic Engineers started by auditing the steelwork to be taken down from the original building, where low-height sixth and seventh floors had restricted floor-ceiling heights and needed to be replaced by three new additional floors.
"We did manage to reuse the old columns to build the new columns being used for those additional storeys," Atkinson explains. "These were taken away, re-fabricated and brought back for reinstallation. As part of that process, we wanted to check [the steelwork's] properties and strength and to assess the steelwork for reuse elsewhere."
At the end of the project, Civic Engineers had a 20t surplus of 1930s steel beams and informed Fore Partnership. Under Fore Partnership, the reclaimed beams were designed into TBC.London with beams on display across the building to educate occupiers and the public about circular economy principles.
Webb Yates director Tom Webster notes that aside from its sustainability benefits, steel reuse is attractive due to the material's innate features.
"Steel has homogeneous properties, so you can take a small sample from a building element and assume that's constant through that element. In addition, the tests are low-cost and easy."
"From the tests, we can extrapolate enough data to assess the steel's ductility, tensile strength and so on and we can apply that to our building. There are SCI guidelines – the SCI P420 Protocol for steel reuse - that can support the design."
He adds that engineering creativity, as opposed to digitally enabled iteration, is critical in steel reuse projects.
"For example, they were demolishing a beam [at 318 Oxford Street] to break the concrete out and they hit its top flange, which was wavy as a result, amounting to a major defect. However, if you turn that beam upside down where the flange is flat, you can reuse it. It doesn't affect the strength performance because the wave is on the tension section, not in the compression zone."
De La Fuente concurs that demolition and engineering smarts, along with detailed planning, were critical to the 2 Aldermanbury Square project.
"The traditional construction method for a steel frame building is a composite slab with a metal deck profile shot-fired to the top flange of a steel structure. There are a lot of components attached, to the top of the steel beam that you're trying to harvest. So, you have to remove the concrete safely.
"Our methodology is to break the concrete out, reducing the weight of the frame. It's more of a traditional demolition at that stage, however once you have the exoskeleton of the existing steel frame left, at that point you do a demolition cut. This entails burning the ends of the beams at a slight angle to allow the beam to be released easily. You then do a trim cut to make it safe for transport," De La Fuente says.
"Once that material has been selected for a project and designed in, it is ready to go back to a fabricator like EMR or Cleveland Steel & Tubes, who can then de-fabricate the steel members, for example by cutting off the shear studs."
Steel extraction entails specific onsite challenges, he notes. "The biggest constraint is cranage, because not only do you have to hold the beam while you cut it, lift it out and place it down; it's also about ensuring that you're maintaining productivity while dismantling the steel, while keeping material disappearing from the site quickly enough that you're not overloading the floor plates with the material."
Walker confirms that for 180 Piccadilly, engineers were able to utilise design similarities between the donor building at City Place House and the new building.
"It was useful that it [the donor building] had long spans because we were trying to create a long span floor plate. We had similar spans and similar grids so we could make best use of the sections [of steel] we knew were coming from the donor building."
Engineers need to be creative in making design adjustments on steel reuse projects, she adds.
"For example, we had to re-fabricate the connections at the ends of the beams and because 180 Piccadilly is a commercial building, it needs service penetrations through the webs of the beams to allow the services to pass through, so those had to be designed in.
"There was certainly some element of re-fabrication, but it still saves a huge amount of carbon compared to melting steel down and re-making it from scratch."
Cost vs carbon
Because steel reuse is in its infancy, calculations on cost and embodied carbon savings are a work in progress. However, what's clear is that at this stage of its evolution, reuse can entail more complexity and cost – despite the lower cost of reclaimed steel – than conventional projects. On the other hand, clients tend to be motivated not by cost, but by the lure of emissions reductions.
Webster notes that pioneering projects entail both risk and reward.
"At TBC.London we bought 100 to 120t of steel from the 318 Oxford Street project and we reused approximately 60 to 70t," he confirms. "There was some wastage in there unfortunately, but that was to do with the makeup of the steel, which was Victorian sections made of layers of plates riveted together. We had to get rid of all the plates that we couldn't use. Ultimately anything you don't use, you can sell into recycling, so you can recoup some money."
On the upside, TBC.London achieved approximately 48t of carbon savings compared to using new steelwork.
De la Fuente notes that, in addition to the onsite complexities of dismantling steel for reuse, processing reclaimed steel entails complexity that can add costs. "Typically, a fabricator will take virgin steel, run it through an automated cut and drill line. But you can't put reused material through automated cut and drill lines because it's out of tolerance for the fine point 'X' of a millimetre that these machines are calibrated to, so you have to revert to manual, labour intensive fabrication methodologies."
He notes however that: "With a blast furnace that spits out coal-fired steel, for every tonne of structural steel that comes out of the factory, it has produced a minimum of 2.8t of carbon. EAF recycled steel produces about 800kg of carbon – a significant saving – and at least you are now into less carbon than steel per tonne. If you then move to a hydrogen powered EAF, that creates 350kg of carbon per tonne of steel. Now we get into the crux of why reuse is so important; a reused steel beam produces 47kg of carbon per tonne."
"The cost of using reclaimed steel is certainly higher because you have to carefully take the steelwork out of the building rather than demolishing it and in that latter case you don't care if it gets damaged," Walker notes. "However, with steel reuse, you're taking already manufactured steel in its current form and using it with a few modifications, rather than melting it down and using a lot of energy to re-form it, or even extracting virgin materials to create new steel, so it saves a huge amount of carbon," she says. "It's a no-brainer really."
180 Piccadilly's use of 450t of reclaimed steel will generate an overall carbon saving of approximately 755t CO2e compared with virgin steel, she confirms.
Walker adds that "given that reclaimed steel typically uses 35 times less embodied carbon than the UK average for new steel, the embodied carbon saving is significant".
Demolition and disruption
Pioneering projects are gradually altering the steel reuse landscape, but the creation of a sustainable supply chain is some way off.
According to the ASBP, a critical gap lies in the underutilised role of demolition contractors.
Between April 2022 and October 2024, ASBP led two 'Delivering Innovative Steel ReUse ProjecT' (Disrupt) research projects; Disrupt I and Disrupt II.
ASBP research associate Asselia Katenbayeva explains that
Disrupt I focused on developing a business model for steel reuse, targeting
organisations across the construction sector including engineers, structural
engineers, main contractors and
demolition contractors.
"It became apparent that demolition contractors are not properly incentivised to recover steel from buildings," she notes, with the result being a stop-start supply of reusable steel.
While to date the two fabricators and stockholders – Cleveland Steel & Tubes and EMR – have focused on purchasing harvested steel, as well as stocking and re-selling it, "we're also seeing cases where demolition contractors are entering the market," she says.
"Demolition contractors would agree with the client that instead of sending steel to recycle, they will be harvesting it for reuse," she explains. "For demolition contractors, [steel reuse] is potentially great because it brings them a competitive advantage."
However, she notes: "For many it's something they're never experienced, which makes it risky. What if they price it wrong? What if there are unforeseen obstacles and project delays in reclaiming the steel?"
As a result of Disrupt I, Disrupt II saw ASBP partner with industry body the Institute of Demolition Engineers to form a working group.
This led to the launch of ASBP's steel reuse toolkit in March 2023, to support demolition contractors and other supply chain participants in dealing with the challenges of harvesting steel.
It includes guidance on recovering steel sections from buildings depending on site conditions and considerations such as programme timeline, effort required and subsequent material recovery. It also provides information on specialised equipment and how to conduct a pre-demolition audit.
Katenbayeva says the toolkit has provided a foundation to enable the participation of demolition contractors, but adds that more can be done.
Legislation requiring demolition specialists to engage in reuse "would definitely help" to establish a steel reuse supply chain, she says.
"It would create a level playing field and enable more players into the market, which ultimately means the cost of this whole process will go down."
Accelerating change
Three of the companies spoken to by NCE – Webb Yates Engineers, Civic Engineers and Elliott Wood – are among six firms involved in The Engineers Reuse Collective (tERC), launched in early December. tERC – whose other member firms are Buro Happold, Heyne Tillett Steel and Whitby Wood – is a not-for-profit group committed to accelerating reuse in the built environment.
Walker notes that the collective builds on efforts made to date by individual firms.
"At Elliott Wood, we've created the building archive – a digital platform for sharing existing knowledge about buildings, and with groups like tERC, more discussions are starting. Hopefully that will help move things along."
Webster stresses that promoting steel's material properties as a candidate for reuse is critical; and he adds that reuse is not limited to buildings.
"Reusing steel is easy, because it doesn't degrade," he says. "You could reclaim old bridges over highways when they get demolished, take that steel and chop it up and use it in buildings or use it in other bridges or structures."
The hope is also that steel reuse will ultimately inform engineering and design thinking for new builds, De La Fuente notes.
"What I would like to see is structures being designed so that they can be dismantled. We install these things with complex connections, so why not design the structure so that you can do that in reverse to dismantle it?"Stay in touch:
