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Urban Mining is revolutionizing the way we think about waste and resources. This innovative approach involves extracting valuable materials from existing buildings and infrastructure, turning cities into repositories of reusable resources. Back in 2019, the Brussels Capital Region adopted ambitious circular economy policies, making demolition in the region not allowed unless there is a good Urban Mining plan for it. Two impressive towers in Brussels showcase the potential of the approach: the ZIN project and the Multi tower. The ZIN project, developed by Befimmo, is one of the largest Urban Mining projects in Europe, spanning over 110,000 m². The Multi tower, developed by Immobel and Whitewood, is a 44,000 m², 18-floor project that stands out as a model of modern urban development and the first CO2 neutral office building in the city. Drees & Sommer, a global consulting company renowned for its innovative solutions in the real estate, industrial, energy, and infrastructure sectors, and its subsidiary EPEA, an international innovation partner for environmentally friendly products, processes, buildings and urban districts, have provided Cradle to Cradle consulting and supported the implementation of circular economy principles in these projects.
Out of sight, out of mind – this phrase aptly describes how we usually treat waste, including the largest current source of it: the demolition of buildings. Today, most building materials end up in landfills, where they are either destroyed or downcycled into products of much lower value. This results in a significant loss of valuable resources. Our resources are finite, and with the growing pressures of urbanization and increasing populations, it is predicted that global demand for materials will triple by 2050. In the EU alone, more than 450 million tons of construction and demolition waste are generated annually.
Michael Moradiellos del Molino, International Head of Sustainability and Circularity, Drees & Sommer: "We need to move away from the mindset of demolition and instead identify and review the existing materials in our buildings. Our cities are dynamic, manmade stock with a unique metabolism, and we are surrounded by more than 50 billion tons of valuable materials.”
Urban Mining addresses the critical issue of finite resources, complementing Cradle to Cradle (C2C) principles and supporting the circular economy. Brussels is home to two projects that highlight the potential of the concept: the ZIN project and the Multi Tower. Both have been supported by Drees & Sommer and EPEA in the integration of circular economy specifications.
ZIN Project: A Landmark in Urban Mining and Circular Economy
The "ZIN" project, developed by the Belgian real estate investment trust "Befimmo", consists of the renovation of towers 1 and 2 of the Brussels World Trade Center. After the dismantling process, the existing towers were joined by a new section featuring 14 doubleheight floors. The multifunctional space of the ZIN accommodates offices, co-working spaces, housing and hotel services on 110,000 m². It was designed by architects Jaspers & Eyers/51N4E/AUC, and reaches a height of around 100 meters. The main part, covering
75,000 m² is for office space use and includes a co-working area. In February 2024, the first entities of the Flemish government moved into their new office building (the MarieElisabeth Belpaire Building), which is part of the ZIN project. A further 14,000 m² is for apartments and 16,000 m² for hotel accommodations, leisure areas, restaurants, and shops.
One of the main ambitions of this project has been to integrate the Cradle to Cradle thinking, through the inventory and reuse of a maximum of materials as well as the Cradle to Cradle Certified® certification of dozens of building materials. Over 1.000 tons of materials, including raised floor, partition, insulation and roof tiles, have been reused, and 140 tons upcycled. Drees & Sommer and EPEA have supported this project with Cradle to Cradle consulting, including the identification of available materials and solutions, demolition support according to C2C, and the implementation of the Material Passport.
Wim Plaum, Project Director at Befimmo: “We know that the future of construction is not just about putting one brick on top of another. It’s about doing it better—for the people, and for the planet that supports us all. That’s why we’re determined to reshape the industry, with sustainability at the center of everything we do.
We strive to set new standards that go beyond the expected. By working closely with our partners and subcontractors, we challenge them to achieve Cradle to Cradle (C2C) certification, because real progress comes when we all move in the same direction.
And we don’t stop there. We focus on reusing materials on-site through urban mining, ensuring every project feeds into a circular economy. This is how we make our shared vision real—by creating a future that is sustainable, practical, and responsible."
Examples of successful collaboration with partners and subcontractors include sustainable and circular waterproofing of approximately 50,000 m2 by Derbigum, circular doors developed specifically for ZIN by Eribel, and Cradle to Cradle Certified aluminium facade outlines by Kyotec Group. Additionally, CCB Concrete transformed 30,000 tons of old concrete from the WTC towers into high-quality, Cradle to Cradle Certified® Silver circular concrete, which was reused as a full load-bearing floor slab in the ZIN reconstruction, marking the first time this has been done in the Benelux region.
Multi tower’s multi-sustainability strengths
Following its renovation, thissignificant project by Immobel and Whitewood, who acquired the building in late 2015, now provides approximately 44,000 m² of office space accommodating 2,000 people, along with retail units. The project has earned BREEAM “Excellent” certification, placing it among the top 10% of new commercial buildings in Belgium.
This is another urban mining monitoring project that Drees & Sommer supported with Building Circularity Passport and Urban Mining passport services. In Multi, 89% of the existing concrete has been reused, saving 3,259 tons of embodied carbon, 20,000 tons of waste, 2,222 cement trucks and 2,000 cement truck journeys. The building boasts the highest percentage of reused materials among large-scale office projects in Brussels, with 3% sourced through urban mining of iconic Belgian locations, in cooperation with circularity partner Rotor DC. Thanks to its energy and carbon performance, as well as its circular economy credentials, the French group TOTAL and Bpost, Belgium’s leading postal operator, have chosen to rent the building.
Valérie Vermandel, Chief Development Officer at Whitewood: "The transformation of the Multi Tower is a testament to our commitment to sustainability and innovation. By turning what was once a dark, heavy structure into a bright, multi-functional workspace, we have not only revitalized the building but also set a new standard for urban development. The Multi tower showcases our dedication to circularity and environmental responsibility."
Laurent Withofs, Project manager at Whitewood: “With renovations you can run into a lot more obstacles than you would with a new build. Old materials can house asbestos, for example, which is a problem that needs to be properly dealt with before we can safely continue with a project. A new build wouldn’t have those issues. This is why I am especially excited to show what we can do to transform old buildings that have gone out of fashion when we think critically and get the right people involved.”
Towards a Regenerative Future
Hein van Tuijl, Managing Director of EPEA Benelux: "Beyond the obvious ecological perks, considering the built environment as a repository of resources can save money and improve health. Our Circularity Passports® provide detailed information on each material’s chemical composition, enabling the use of non-toxic materials in construction and eliminating health risks at each stage of the circular material use.”
Since the inception of the EU-funded research project Buildings As Material Banks in 2015, EPEA has issued hundreds of passports, continuously refining them to promote the circular use of materials in construction. It is important to emphasize that the Cradle to Cradle approach differs from traditional recycling, which often includes downcycling or energy recovery methods that are detrimental to climate protection and resource conservation.
The Circularity Passport® describes the value of materials for circular use, including their ability to be separated, deconstructed, and reused during conversion or demolition, thus transforming buildings into valuable repositories of raw materials. This passport also includes carbon footprints, including the “grey energy” from the production, transport, deconstruction, and disposal of building materials, providing a comprehensive life cycle assessment. This tool aims to pro-actively inform stakeholders about how to select the right materials and how to apply them in a circular way.