The construction industry has been identified as the world’s largest consumer of raw materials, with 3 billion tonnes being used in the manufacturing of building products. In the UK alone the industry consumes over 400 million tonnes of material each year* much of which goes on to become waste within a few decades.
 
#CEweek, the circular economy showcase, saw a blend of in-person and online events exploring how cities are adopting circular strategies to reduce waste and carbon emissions. There was a heavy focus on construction, which is understandable, given that 60% of London’s waste is created by the industry**.
 
The week’s events were hosted by ReLondon, who is currently undertaking the CIRCuIT project (Circular Construction in Regenerative Cities) funded by EU Horizon. Research as part of the project recently revealed the significant appetite for more reuse, with participants citing both environmental and economic benefits, and steel was identified as one of the materials that held huge potential.
 
An integral material for the industry, construction accounts for nearly 50% of all global steel production. The World Steel Association revealed nearly 2 billion tonnes of steel were produced in 2020, the energy-intensive process of steelmaking generates around 8% of global CO2 emissions. The opportunity to reduce its environmental impact can only be achieved through increasing reuse. As currently 95% of all steel is recycled, but even with the best available technology, it is an energetically expensive operation.
 
The event ‘Making steel reuse best practice in the construction industry’ saw insightful presentations and discussions on how we can overcome industry challenges to reusing steel with perspectives from speakers on the forefront of making steel reuse happen across the sector. Chaired by ReLondon's Built Environment Lead, Andrea Charlson, speakers included Tim Biggin, Senior Site Manager at Blenheim House Construction, Penny Gowler, Director & Head of sustainability at Elliott Wood, the structural and civil engineering practice and Roy Fishwick, Managing Director of Cleveland Steel and Tubes.
 
Cleveland Steel and Tubes is a Yorkshire-based company that has over 45 years of experience in reprocessing and repurposing steel. Roy Fishwick has been actively promoting the benefits of reclaimed steel for many years, explaining its virtue “steel doesn’t deteriorate, it can stay in a structure for hundreds of years. Therefore it can potentially be fit to perform in structures for hundreds of years, even if they are not the same ones.”
 
The company supplies steel to infrastructure and national construction, high profile past projects include the Olympic stadium in London, the roof at Wimbledon and most recently the Queen’s Jubilee 'Tree of Trees', made of repurposed steel tubulars, a source of pride and joy for Cleveland Steel. During his presentation, Roy explained the reuse of steel is not a new concept, “we are not reinventing the wheel” he says, but over the years the market for reclaimed steel died out “It just hasn’t been happening on the scale that it once used to.” The biggest challenge he sees for the reuse market is the sourcing of materials, incentives for recycling are so strong it has become dominant. Observing the current model of building “the onset of construction is done without thought for the material ... nobody worries where the materials are coming from.”
 
Giving a design team perspective, Penny Gowler, of Elliott Wood, noted the shift she has witnessed over the past 18 months, “there is much greater demand from clients for low carbon alternatives on their projects.” No doubt propelled to meet their own sustainability targets, but financial reasons and material availability were also cited as key drivers for clients seeking to reuse.
 
A comparison of steel currently on the market illustrated her point. New steel had the highest impact with the embodied carbon totalling 1,740kg CO2e per tonne. A ‘green’ recycled steel (note this is only available in limited quantities) worked out as 330kg CO2e per tonne and the reclaimed steel was 60kg CO2e per tonne. These figures clearly show the benefit of choosing to reuse steel, a practical strategy that would radically curb carbon emissions.
 
7 Holbein Place, a project which sees an eighties commercial building transformed into Grosvenor’s flagship commercial office development. Sustainability was at the core of all decision-making and heavily guided the design. Site Manager, Tim Biggin explained how utilising reclaimed steel was a key strategy to outperform other developments with regard to its carbon footprint and attain both BREEAM and WELL accreditation.
 
The project involved structural alterations and extension, the new design saw the roof being removed and two new floor structures being erected out of steel and cross-laminated timber slabs. The existing facade is retained and extended in matching bricks, many are reclaimed sourced from salvage yards and the mortar is a lime product to also reduce the carbon.
 
“One of the main features of the zero-carbon build is the reuse of the steel structure which came out of the existing roof” explained Tim. The steel was kept to the longest lengths to maximise the reuse options and once removed it was decided to be used for another of Grosvenor’s projects.
 
The key finding from the project was how early discussions to set reuse goals and engagement with all parties helped increase reuse. From the outset, the structure contractors were specified to supply and install approximately 40% of the new structure from reclaimed steel, during the fabrication this was surpassed to 50%. The steel integrated was from Cleveland Steel, they were able to incorporate more reclaimed material when stocks became available because the client was flexible in their approach and specification allowed for this.
 
The fabricated steelwork in 7 Holbein Place was CE marked by the Cleveland Steel team to comply with regulations. The testing of reclaimed steel is in no way an inferior methodology explained Roy “you can demonstrate all properties of steel that would be demonstrated with a newly milled steel, such as the grade and strength.” Noting that the process is at a greater level of detail than the standard tests at a steel mill.
 
We are in a period of transition within cities, the GLA New London Plan requires circular economy statements on projects, Penny explains “it is very difficult to demolish a building and build something new without strong justification.” This strategy is seeing developers adapt their current practice with more consideration about whether to demolish or deconstruct a building and also the importance of salvaging those materials for reuse within their own development programme to lower their carbon emissions.
 
Speaking of a live project, Penny shared diagrams of an existing donor nineties building, that consists of approximately 2,000 tonnes of steelwork. Working with the client they plan to salvage a large proportion of the steel and reuse it on a new build project, within London, that requires 720 tonnes of steel.
 
The development of dialogue between projects is an exciting evolution that will hopefully increase reuse in construction, as what might be discarded in one project could be the perfect solution for another. In any case, it will actively encourage ownership of materials that have for too many years been disregarded as disposable waste.
 
With that, I’d like to close on Penny word’s to all those involved in the process of design and construction to raise the issue of reuse “Don’t let demolition happen without questioning it, and questioning whether those materials can be recovered and reused.”
 
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Statistics taken from;
* ‘Circular economy in the built environment’ (May 2019) by BSRIA a ISO 9001-registered test, instruments, research and consultancy organisation.
**ReLondon