The use of modern construction methods (MMC) makes it much more difficult to reuse materials when a building is demolished, built environment experts have warned.
Howard Button, chief executive of the National Federation of Demolition Contractors (NFDC), said the composite materials used in MMC projects are “nowhere near as salvageable” as traditional materials found in older buildings such as the Victorian dwellings.
Several industry groups have campaigned for more widespread reuse of materials such as steel and wood, a practice that is increasingly seen as an important way to reduce embodied carbon during the construction of demolition and renovation projects. reconstruction.
Last week the UK Green Building Council (UKGBC) published a report calling for the establishment of an agreed metric to report carbon savings from reusing materials.
Climate campaign group Architects Declare, which is backed by practices including AHMM, Haworth Tompkins and DSDHA, urges signatories to work towards a circular economy in the built environment by reusing as many materials as possible from buildings to reduce waste at least.
The same groups have also championed MMC approaches such as modular construction as a necessary means to move the industry towards net zero emissions.
But Button said composite materials, which are glued together and cannot be easily separated and turned into source materials, are a “problem for the [demolition] industry”.
“If we really want a circular economy, we have to look at what we put in it to make sure we can eliminate it in the future,” he said.
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Rachel Hoolahan, architect and sustainability co-ordinator at Shoreditch practice Orms, said the specification of composite materials by designers without considering their viability for future reuse is “accidental”.
“They just didn’t think of it. They just try to do their job to create the best possible building for their clients, but I think sometimes they just don’t realize the true impact of it,” she said.
“One thing that’s very easy to fall for is that you might think you’re doing the right thing by sticking materials together, but in fact, inadvertently sticking them together so much that we can’t take them apart.”
Robin Powell, former managing director of demolition company DSM, said builders “don’t think about demolition at all” when designing and constructing buildings.
“I see time and time again with the people who were designing both the components and the complete building that the last thing on their mind was recycling and reusing the components.”
He said “virtually nothing” of an MMC student accommodation block at Birmingham City University could be reused after it was demolished by DSM in 2020. The volume of materials that could be recycled has fallen by 30% compared to a traditional building structure.
Reusing materials has also become much more difficult in recent years due to tougher building regulations, including those that set minimum standards for thermal efficiency.
“Years ago, all [demolition] contractors used to take steel and sell it back into the construction industry,” Button said.
“This type of steel reuse stopped when much of the building code became so strict and specific that it was very difficult to find used steel that was code compliant and could be certified.”
Only 1% of building materials in northwestern Europe are reused after their first application, according to figures from FCRBE, a European Union project aimed at increasing the reuse of materials. Up to 30% of a Victorian home can be reused after demolition, including bricks and timbers, Button says.
Ben Griffiths, director of operations at demolition company Rye Demolition, said reusing materials such as steel is often “more hassle than it’s worth because of the requirements” and said that customers often regard materials audits on rebuilding projects as a “BREEAM tick”.
Last year, Orms proposed a new system for collecting information about materials in buildings to decide if they can be reused. The practice said architects could use their phones to scan QR codes printed on materials in buildings to access recorded data, including fire ratings and maintenance information.