EARTH: A CIRCULAR CONSTRUCTION MATERIAL
By Tom Morton, Arc Architects, EBUKI & SEDA
A Knowledge Exchange & Strategic Options Mapping Workshop
As the construction sector grapples with significant waste and resource inefficiency, transitioning to a circular economy is more crucial than ever.
THERE IS A HUGE OPPORTUNITY TO TURN WASTE INTO RESOURCE THROUGH CONSTRUCTION INNOVATION.
This was the key message from an Emerging Practice workshop co-hosted by Zero Waste Scotland, Earth Building UK & Ireland and Scottish Ecological Design Association, which brought together leading practitioners in earth up-cycling from Germany, France, Belgium, Ukraine, England and Scotland.
The recent Circular Construction Act in Scotland has identified soil and stone as a key theme for delivery because of the vast volumes of wasted material and energy, the relative ease of adaptation within supply chains and the financial incentives already in place ahead of whole-life carbon regulation.
Andy Sullivan from SEPA (Scottish Environment Protection Agency) underlined the scale of opportunity - a third of all Scottish waste, 3 million tonnes, is earth derived from construction activity – currently landfilled, dumped illegally, or diverted to low value uses.
Rowland Keable of HG Matthews Ltd and Nikolay Shahpazov of Bennetts Associates described an alternative approach trialled in commercial development in London, where demolition materials are up-cycled into pressed blocks, brought back to site to be built into walls – turning what would be waste into high-value resources, while avoiding disposal costs and the impact of new materials.
It’s a similar story across Europe, though often on a larger scale, with further routes to innovation being piloted. In Germany. Christian Gath from BauhausErde explained how new DIN standards have enabled new earth products to come to market at scale to displace high carbon/resource products like concrete blocks and floor systems.
In France, Stephane Kirkland described how a cross-sector collaboration has enabled city-scale resource up-cycling in Paris. National policy now requires nature-based materials in public buildings, a move that is fostering market demand and influencing the private sector.
20 million tonnes of earth are excavated in the Paris region every year (pic: S. Kirkland)
Ken De Cooman of BC Materials shared how Belgium introduced a temporary relaxation of outdated regulations, allowing ‘waste’ to become resource - a vital state intervention to enable market transition.
What’s emerging is a shift away from the historic linear flow of materials from the construction sector into the waste sector for disposal, towards an increasingly integrated system that enables up-cycling and circular construction in practice. These case studies illustrated how we are learning to ‘mine’ the urban fabric - developing the materials, processes and partnerships to renew the built environment from itself.
The direction of travel - from pilots to policy, from fringe to norm - is clear. But achieving this will require clear intent, updated regulation, investment in innovative, and leadership in public procurement to incubate the market and bring forth a new generation of construction practice.
Sarah King and Claire Baily described how the vast HS2 infrastructure project in England is attempting to address this at scale, while Becky Little of Rebearth showed how the same principles are being applied in small-scale construction -often overlooked in strategy, but the essential bedrock of the industry. She reminded us that traditions of circular building practice go right back to the first buildings of the Neolithic.
What was missing from the room, was representation from the soil waste industry in Scotland. This is significant given the country hosts one of the highest concentrations of earth-washing plants – facilities that separate aggregates for concrete leave behind massive volumes of waste silts and clays. This is not the circular economy, it perpetuates a cycle of single use extraction, sustained by current market dynamics.
The sector recognises the looming crisis: aggregate supply is faltering, and sand is now considered an endangered global ‘resource’. The answer is not to import materials, but to reduce demand for single use products and build circular systems. A transition from cement-based to clay and organic binders is a key pathway – and is crying out for structural investment.
As Ken reminded us, beyond technical and logistical barriers are, this is ultimately a cultural challenge.
We must recognise current construction culture as a stranded asset - one we must stop investing in. Every year, millions of tonnes of earth are extracted, transformed into materials and products, and then discarded as waste. Earth begins as nature, becomes a resource, then a material, then a product—and finally, waste—dumped back into the ground.
Yet, we can see signs of new culture. The Chapel of Reconciliation in Berlin, built by artist and earth builder Martin Rauch, used the debris from the former church - blown up to create clear firing lines during the Cold War – and remade it into the new church’s rammed earth walls - a powerful symbol of renewal and reconciliation.
So how do we bring that spirit of reconciliation to an industry that is, in many ways, in conflict with Nature?
Why is it so difficult for wealthy countries, living in peace with democratic governments to find the will and resource to change? And how much harder must it be for countries outside the global north – or for places like Ukraine, facing the challenge of renewal amid the waste of war?
The key learning from our gathering was this: change is enabled through shared knowledge and experience. That is the path, as Christian reminded us, that turns dirt into gold.
Tom Morton, Arc Architects, EBUKI & SEDA