Kelly Sempels comes from a family of builders. Her father was in construction, most of her five brothers followed suit, and she herself was a builder until recently. After a career spent repairing roofs and laying bricks, Sempels has transitioned to a novel profession: “urban mining.” She and her team of six still present and converse like construction workers, but their current work centers more on deconstruction than building.
Urban Mining in Leuven: Dismantling Waste, Building a Circular Economy
“I appreciate the opportunity to learn something new at work,” remarks the 43-year-old, gesturing towards a stack of laminate flooring in the corner of a townhouse she is helping to dismantle. “Like learning techniques to remove wooden floors without damaging them.”
Sempels participates in an ambitious initiative in the historic Belgian city of Leuven, involving hundreds of workers and volunteers, aimed at diminishing waste and fostering a “circular economy.” This strategy, outlined in 28 “action points” in the city’s official circular plan, seeks to curtail material consumption and promote a more conscious approach to planetary resources.
Vision for a Circular City
Thomas Van Oppens, a member of Belgium’s Green party and Leuven’s deputy mayor, champions this vision. From his office, overlooking the cityscape towards Leuven’s medieval heart, he articulates an inspiring future for Leuven where everything, from kitchen scraps to excess industrial heat, is captured, repurposed, and continuously reused. His guiding principle is clear: “What enters the city, stays in the city.”
Prioritizing the Built Environment
Van Oppens’ environmental idealism is grounded in the practical necessity of establishing a solid base for the city’s circular economy initiatives. This pragmatism led to the initial focus on Leuven’s built structures. “Our city’s ambition is to achieve carbon neutrality [by 2050],” he states. “Buildings significantly impact the climate, making them a key area of focus.” The European Commission estimates that buildings consume approximately 40% of the EU’s energy and contribute over a third of the EU’s energy-related greenhouse gas emissions.
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Identifying Salvageable Materials
The process begins well before Sempels and her urban mining team arrive with their tools. Leuven’s urban planning department collaborates with architects and developers to pinpoint buildings slated for demolition and assess the potential for material recovery. While the European Commission has backed pilot projects utilizing 3D scanners and other digital technologies to identify reusable materials, the current method primarily involves a swift evaluation by a material recovery specialist. In Leuven, this role is filled by Materialenbank, a non-profit organization dedicated to promoting the recovery and resale of construction waste, diverting it from landfills.
Ward Verstappen, Materialenbank’s logistics and urban mining manager, stands with Sempels in the partially dismantled living room in Leuven’s Kessel-Lo district. Indicating the hallway and ground floor rooms, he lists the most sought-after materials: bricks, stone, roof tiles, steel beams, wooden panels and flooring, and carpentry elements like doors and window frames.
Reuse and Downcycling
Verstappen explains that some salvaged items can be directly reused after minimal refurbishment, such as sanding or a fresh coat of lacquer. For items that are too damaged or fail to meet safety standards, “downcycling” presents the next viable option. This involves repurposing materials for less demanding applications; for example, steel girders can become scaffolding, and roof tiles can be used for interior walls.
The two-story houses are part of a pre-war residential block near Leuven’s train station, designated by the city council for demolition to create green spaces and alleviate traffic congestion. These buildings are among approximately 30 houses and garages that Materialenbank plans to “mine” in the coming year.
Social Economy Integration
Leuven’s circular economy plans prioritize social rehabilitation alongside material reuse. Belgium hosts numerous initiatives promoting a “social economy” that prioritizes people over profits. Sempels exemplifies this approach, having secured her position after a prolonged period of unemployment, as did another Belgian member of her team. The remaining five team members originate from Iraq, Palestine, Ethiopia, Mali, and the Caucasus region.
All team members are employed by Wonen en Werken (Living and Working), a social enterprise providing various community services, including park upkeep, cleaning, renovation, and landscaping. The organization employs around 200 individuals, offering minimum wage or slightly above, with salaries partially subsidized by the Flemish government. “We primarily employ individuals who have experienced long-term unemployment, have lower levels of education, and face personal challenges… While they may have difficulties, they also possess significant capabilities,” states Patrick Wauters, employment coordinator at Wonen en Werken.
Materialenbank: A Hub for Reuse and Innovation
This synergy between social and environmental objectives is also evident at Materialenbank’s warehouse located on the city’s outskirts. This expansive facility includes a spacious area for cleaning and storing salvaged construction materials, as well as workshops available to local artisans and entrepreneurs for creating new products from these reclaimed resources.
Bram de Ridder, a 22-year-old climbing enthusiast, is among these entrepreneurs. He is establishing a small business producing climbing wall holds made from reclaimed wood. After learning about Materialenbank from a friend, he now regularly utilizes the facilities to refine his skills and launch his venture. “Previously, I used scrap wood from my father or scavenged for old furniture. Now, I come here to access equipment and utilize materials that would otherwise be very expensive,” he explains.
Growth and Future Expansion
Materialenbank’s primary role is connecting suppliers of Leuven’s construction waste with property developers and builders. Since its inception three years ago, the initiative has witnessed a tenfold increase in annual sales, from 20 to over 250 tonnes. Coordinator August Smessaert notes they are seeking larger premises to accommodate further growth: “The current location presents challenges for heavy trucks accessing the site, and gate heights are restrictive… We estimate potential recovery volumes exceeding 5,000 tonnes by 2030.”
One potential solution involves direct pickups by buyers from demolition sites, bypassing warehouse logistics. Smessaert notes this is feasible for materials like bricks, steel, and iron, which already have established secondhand markets. However, it is more challenging for materials requiring significant restoration or when new materials are comparably priced or cheaper.
Overcoming Market Challenges
Consequently, Materialenbank prioritizes wood collection due to strong demand and reasonable profit margins. However, finding buyers remains a challenge, Smessaert acknowledges. Building contractors often exhibit skepticism towards innovative approaches and prefer the predictability of new materials. Recycled material supply can be inconsistent, with fluctuating volumes and variable quality.
Institutional Partnerships Driving Demand
To address these issues, the city council has partnered with three of Leuven’s major institutions: KU Leuven university (600 years old), University Hospitals Leuven (Belgium’s largest hospital), and Imec (semiconductor specialist). These institutions have committed to both providing waste materials to Materialenbank and incorporating recovered materials into future construction and renovation projects.
For example, when the university hospital planned to construct a student “chillout zone” and administrative area, its construction department explored reuse options. This resulted in two recently completed structures largely built from materials destined for disposal.
Adding Character Through Reuse
According to Paul Lodewijckx, head of new builds and labs at the hospital, incorporating reclaimed items brings unique character to a space. He points out the staircase and wall bench, both made from beech trees felled during a storm. Pine beams in the mezzanine originate from dismantled pallets, and kitchen units are crafted from fiberboard offcuts from Imec’s offices. Lodewijckx highlights his favorite piece: a long walnut and MDF table in the chill-out area, previously part of an art museum exhibition.
Leuven offers further examples of circular construction. A distinctive, multi-level wooden structure in the historic center, used for urban sports and cultural events, was repurposed from the city’s former velodrome. Additionally, three recently renovated social housing units near De Bruul Park feature new beds, flooring, kitchen units, and cupboards constructed from recycled wood.
Scaling Up Urban Mining
Despite the potential of Leuven’s circular construction initiatives, most remain in the pilot phase. Achieving Van Oppens’ vision of a fully circular city requires further action. Stricter regulations could be instrumental. The European Commission’s proposed circular economy act could mandate reuse obligations for all construction projects. Other European cities are already implementing circularity requirements; Zurich, for instance, requires all public buildings to be built using a minimum of 25% recycled concrete or other aggregates.
Shifting Mindsets for a Circular Future
For urban mining to truly flourish, residents’ attitudes must evolve, extending beyond just builders. Kobe Vaes, an engineering graduate coordinating Maakleerplek, a multi-use repair and reuse center located near the former Stella Artois grain silos, emphasizes this shift. He believes the innate inclination to discard should transition to considering potential uses, either personally or for others.
Maakleerplek: A Community Hub for Repair and Reuse
Maakleerplek features a large maker-space equipped with 3D printers, lathes, presses, and other DIY tools, alongside carpentry equipment and diverse materials like Perspex, plywood scraps, and fabric strips. Amidst this organized activity, schoolchildren regularly utilize the center to create key fobs, phone cases, cheeseboards, and various crafts. “Each summer week, we take kids canoeing on the canal to collect plastic waste, which we then repurpose in the workshop,” Vaes explains.
Maakleerplek also houses a small clothing repair business staffed by immigrants, a textile workshop with knitting machines for local tailoring instruction, and a tool “library” offering residents equipment rental from ladders to drills for an annual fee of €40 (£34). This center is part of a growing network of repair cafes, thrift stores, and similar reuse initiatives emerging across the city. These efforts are gradually transforming public perceptions of the reuse economy, shifting it from something “stigmatized” to something “fashionable.”
Kringwinkel: Secondhand Shopping Reimagined
Sofie de Brouwer, a cleaner at a Leuven nursing home, embodies this shift in perception. She frequents Kringwinkel, a secondhand store in downtown Leuven, during her weekly grocery shopping. Part of a four-store chain in the city operated by ViTeS social enterprise, Kringwinkel resembles a conventional department store, but stocks exclusively pre-owned items.
“I recommend Kringwinkel to all my friends,” says de Brouwer, wearing an €8 winter coat and a €4 leopard-print handbag purchased on previous visits. “High-street stores offer curated, uniform selections. Here, everything is unique and vintage, which I find very appealing.”
A Vision Realized
Back at the soon-to-be-demolished house in Kessel-Lo, Sempels also embraces the circular approach to waste. She proudly displays pictures on her phone of newly installed council bins on the street, constructed from salvaged wood planks that she helped recover. “Seeing what these salvaged materials become makes me happy,” she concludes. “It’s beautiful, don’t you think?”