[Photos by Andrew van Leeuwen unless noted otherwise]
This fall, BUILD sat down in Stockholm with architect and professor Erik Stenberg to discuss how the circular economy is reshaping architecture—from rethinking demolition and material reuse to redefining the lifespan of concrete itself. Stenberg shares insights on sustainability, innovation, and why the future of building lies not in creating more, but in rebuilding what we already have.
Tell me about your own trajectory and how you got to where you are.
I studied architecture in the United States, graduating from Virginia Tech in the early 1990s, before returning to Sweden to practice. In the late ’90s, I joined a project renovating an apartment from Sweden’s Million Program—a national initiative that produced a million homes between 1965 and 1974 to address the postwar housing shortage. The building, a model of flexible structural design, became an exceptional case study.
After completing the renovation, I moved into the apartment myself, gaining a rare user’s perspective on the work. Despite frequent criticism, I found these environments deeply valued by their residents. Over the twelve years I lived there, I continued to practice independently, teach architecture, and organize housing fairs, deepening my fascination with postwar construction methods.
Later, as head of the architecture department at KTH in Stockholm, I launched a program to broaden access to architectural education—inviting students from more diverse socioeconomic backgrounds, including those raised in postwar housing estates. My combined interests in tectonics and inclusivity ultimately led to my role leading the Swedish branch of ReCreate, an initiative founded by Finnish architect Satu Huuhka.
What is ReCreate, and what’s its mission?
ReCreate aims to drastically reduce the carbon footprint of new buildings by reusing precast concrete components not designed for disassembly. They are sourced or harvested from existing buildings to be demolished. The program’s larger goal is to build a circular economy around construction materials—especially precast concrete panels. These panels, common in the housing of the 1960s and ’70s, are carefully disassembled, tested, certified, stored, and reassembled into new projects.
When implemented at scale, the system can reduce carbon emissions by 70–90 percent and, importantly, also reduce demolition waste. It’s a genuine game changer for how we think about buildings and resources. ReCreate is now established in Finland, Sweden, the Netherlands, and Germany, with work on four pilot projects already providing valuable data and feedback.
[Deconstruction at the Återhus project in Solna, Stockholm]
Explain the environmental impact of producing new concrete.
Concrete’s carbon footprint is twofold. First, firing the kilns that heat limestone requires enormous energy. Second, the limestone itself releases CO₂ as it’s transformed into calcium oxide, the key ingredient in cement. These combined emissions make concrete one of the most carbon-intensive materials on the planet.
ReCreate’s process interrupts that cycle. By deconstructing existing buildings, testing and reusing their components, we keep the embodied carbon in circulation and avoid creating new emissions altogether.
How strong are these reused components compared to new ones?
Concrete actually continues to gain strength for decades. The chemical process of hydration never really stops—it just slows. While most concrete is tested for structural capacity after 20 or 30 days, it continues to harden over time. So when precast panels are dismantled and reused through ReCreate, they’re often stronger than when they were first installed.
What’s a reasonable lifespan for precast concrete panels?
Without reinforcement, concrete alone could last around two thousand years. With steel reinforcement, oxygen eventually reaches the steel and causes corrosion, which leads to cracking. Even so, Swedish precast concrete is of such high quality that panels typically last 100 to 150 years, depending on exposure. Exterior panels—such as balconies or parking garages—tend to have shorter lifespans due to weathering, but the overall performance is impressive.
And if panels are damaged or weathered—can they still be used?
Yes. Both the concrete and the reinforcing steel can be downcycled. The concrete can be crushed for road base or fill, and the rebar can be melted and reused. Our goal is to keep materials circulating within the construction loop for as long as possible before they become waste.
[Harvesting reusable concrete panels from the Återhus project in Solna, Stockholm]
How is this approach changing the construction industry?
Traditional demolition is being replaced by deconstruction—a more careful, craft-based process that values precision over speed. It requires new skills and new business models. Instead of simply tearing down, companies now disassemble, test, store, and resell building parts. That creates a new chain of accountability and revenue.
This transition also raises big questions: who gets credit for the carbon reduction? The demolition company? The owner of the original building? Or the contractor of the new project? These are the kinds of challenges we’re working through right now.
What are the main obstacles to wider adoption?
The biggest hurdle is economic. Virgin materials are still far too cheap. As long as new concrete and steel cost less than reused components, the ReCreate model will remain an “innovation” instead of the norm.
Permitting systems are another challenge. Most demolition permits still measure material in cubic or square meters, which doesn’t translate well when you’re cataloging specific reusable components. We need a system that recognizes and tracks building parts directly.
Are there examples of companies already shifting toward reuse?
Yes, and they’re setting a precedent. In the Netherlands, the company Lagemaat evolved from demolition into deconstruction and now runs a warehouse and showroom for reclaimed components. In Belgium, the firm Rotor specializes exclusively in reused building parts, while the Danish practice Lendager integrates a materials store directly into its architecture business. These examples show that the model can be profitable as well as sustainable.
What kinds of innovations are being explored to improve efficiency?
We’re looking closely at sequencing and storage models. The simplest approach is to deconstruct a building, store the materials on site, and then build anew—as we’re doing at the Återhus project in Solna, Stockholm. But that’s only possible when there’s enough space.
The next step is overlapping the processes: dismantling one building while construction begins on another, reusing materials in real time. That would compress project timelines and cut costs. Off-site storage and marketplaces for reused parts will also play a big role, likely involving companies that already distribute new materials—they have the infrastructure and know-how.
[Stacks of reusable concrete panels at the Återhus project in Solna, Stockholm]
Do you see financial incentives emerging for building owners?
Possibly. A more likely scenario is that deconstruction companies, rather than owners, profit from the recovered parts—they need compensation for the extra care, time, and equipment the process requires. Some firms are already considering owning their own storage warehouses and becoming material resellers.
How could politics accelerate this transition?
If carbon taxes were introduced, reuse would become immediately cost-effective. It would be cheaper to harvest and reassemble existing components than to extract raw material and process it into new concrete or steel.
We’re not quite there yet, but the Nordic countries are moving in that direction. There’s strong awareness of the climate crisis, and both top-down and bottom-up initiatives are underway. Interestingly, the private sector often shows more urgency and creativity here than mid-level politicians.
[Academic project and image by Erik-Sjöberg]
How does this work influence your role as a teacher?
In my studios at KTH, we explore flexibility and design for disassembly. Students ask critical questions: Should components be standardized? Modularized? Built on-site or off-site? How do we measure value when the real profit—reducing carbon—may not be realized for 50 or 100 years?
[Model and photo by Erik-Sjöberg]
Once students work through these questions, they become more aware of how buildings are constructed and what those choices mean for the climate, economy, and people. My goal is to give them that awareness—that sense of responsibility for what already exists.
[Academic project and image by Kinga-Zemla]
How do EU programs like ReCreate receive support?
There’s significant research funding across Europe for innovation in construction. ReCreate, for example, receives 12.5 million euro over several years, with about half of that directed to private companies developing new methods for deconstruction and reuse. That mix of academic and commercial collaboration is crucial—it keeps the research grounded in practice.
What was the H22 Pavilion, and why was it significant?
The H22 Pavilion in Helsingborg was a small-scale proof of concept for ReCreate, built for the 2022 City Expo. It combined parts from four different deconstructed projects: slabs from an old preschool, columns from a storage building, hollow-core slabs from an office, and wall panels from a housing project. Getting everything to fit was a challenge, but it showed that the system could work in practice—not just theory.
[H22 photo by Jonas Linné]
Who are the architects leading the way in reuse at the building level?
Lacaton & Vassal in France are great examples. They’ve built a career on working with existing structures, refining and expanding them rather than replacing them. Their 2021 Pritzker Prize recognized precisely that approach—an architecture of care and adaptation.
What do you think this means for the future of architecture?
Architects will need to shift their focus from creating new icons to maintaining and transforming what already exists. Much of that work will deal with unremarkable, everyday buildings—but that’s where the real environmental and social value lies. The discipline is slowly rediscovering the beauty of repair, and I think that’s a healthy direction.
What books or texts would you recommend for understanding this shift?
• Buildings Must Die by Stephen Cairns and Jane M. Jacobs
• Umbaukultur: The Architecture of Altering by Christoph Grafe and Tim Rieniets
• A Global Moratorium on New Construction by Charlotte Malterre-Barthes
• ReCreating the Construction Sector for Circularity: Catalysing the reuse of prefabricated concrete elements by Satu Huuhka, Leena Aarikka-Stenroos, Jukka Lahdensivu, Paul Jonker-Hoffrén, Viktoria Arnold, Erik Stenberg, Rijk Blok, Kjartan Gudmundsson, Patrick Teuffel, Angelika Mettke
Erik Stenberg is an architect and Associate Professor at the KTH Royal Institute of Technology in Stockholm, focusing on post-war mass housing systems and prefabrication methods. He leads the Swedish country cluster of the ReCreate project, which explores reusing precast concrete elements to create a more circular construction industry. With professional experience spanning practice, research, and teaching, he has been involved in transforming large-scale modernist housing estates and advancing sustainable building technologies.