Challenging the Construction Industry: A Conversation with Rotor, Part 2

[All photos by Andrew van Leeuwen]

Rotor is a Brussels-based cooperative that has reshaped how architects think about materials by turning reuse into a functioning market. Known for salvaging, conditioning, and reselling reclaimed building components, their work makes reuse reliable and specifiable at the pace of real projects. This past winter, BUILD sat down with Michaël Ghyoot and Cécile Guichard at their Brussels facility to discuss how they are building the infrastructure for a reuse-driven construction economy.  Read part 1 here.

Is there a sweet spot of demolition? In other words, does a building need to be demolished to a certain threshold to make the salvage process worth Rotor’s time?

Michaël Ghyoot: From our perspective, the less demolition, the better. Total demolition happens too fast to allow careful salvage. When most of a building is preserved, material flows are reduced and reuse becomes more feasible. Keeping about 80 percent of a building is ideal for our purposes; it allows for a more thoughtful assessment of materials and a more careful disassembly.

Cécile Guichard: Reuse needs time, and in cities, time is money.

What are the various avenues in which you acquire materials?

MG: We acquire materials through three main pathways. First, our own team dismantles materials on site, usually before the general contractor. Second, contractors dismantle materials themselves and sell them to us directly, which effectively turns every contractor into a potential salvager. Third, individuals or companies bring materials directly to us, either for sale or on consignment.
Early on, we had to actively seek materials. Today, we receive hundreds of proposals and focus mainly on materials we know will sell.

CG: For many contractors, it’s also about recognizing value. They don’t like throwing good materials away.

[Rotor DC warehouse in Brussels]

How is the dismantling occurring on site in order to ensure that you have products you can resell?

MG: Most of the time we contract directly with the building owner, and ideally, we intervene before the demolition contractor arrives. This goes back to the distinction between waste and product. By organizing a prior phase for the careful dismantling of reusable items—rather than mixing everything into containers as general waste—you preserve the status of the material as a product.
That’s the first pathway. The second is that we’ve realized most contractors already know how to salvage materials. If you know how to install a door, you know how to uninstall it. If you know how to build a wall, you usually know how to unbuild it. But selling those products back on the market is a completely different business.
So, what we do is buy the materials directly from the site. The contractors take care of the dismantling. It may take them a bit more time than a fast demolition approach, but we compensate them by purchasing the materials. For us, it allows us to build a larger and more diverse inventory.
What’s really interesting is that this turns almost any contractor into a potential salvager. People who are already in daily contact with reusable materials now have a channel to activate this operation. After two or three years of trial and error, this became a decisive step for us.

[Rotor DC lighting showroom in Brussels]

Given the high amount of labor involved in salvaging these items, how do you ensure that you make a profit on the final product?

MG: Over the years, we’ve learned to only take in things that we know are going to sell and whose price we can roughly estimate. That way, we can judge whether an opportunity makes economic sense.

How difficult is it to test and certify salvaged materials for resale?

MG: You might think that load-bearing components like columns and beams require the most stringent testing, but even very mundane elements—like carpet tiles—have rigorous standards to meet. The requirements are different, but they can be just as complex.
How does the carpet tile wear? What volatile components does it emit? Does it still meet current code thresholds? All of these criteria apply to a simple carpet tile, whereas a glulam beam mainly has to meet baseline strength and resistance requirements. The inspection information we provide is usually enough to determine whether a material is a good fit for a project; however, sometimes on larger projects, the client is required to undertake additional testing.

[Reused glue-lam beams at the Recypark project in Brussels]

Rotor’s Zinneke project brings many of your ideas about reuse, flexibility, and coordination into a single built example. Can you explain what the Zinneke project is and why it’s significant for your work?

CG: Zinneke is a mixed-use project in Brussels that was designed by Ouest Architecture. It became a kind of real-world test case for how far reuse can be integrated into an architectural process when the client and design team are genuinely committed. It combines reused components at multiple scales—from windows and interior elements to major building services—while requiring close coordination between owners, engineers, contractors, and public authorities.
What made it particularly important for us is that Zinneke helped establish new precedents with permitting bodies, showing that flexibility around specifications and reclaimed materials can be formally accepted and even inform future urban regulations.

[Zinneke office in Brussels]

What’s an example of how this project informed future urban regulations?

MG: We were planning to reuse several windows in the project, but we didn’t know which salvaged windows would be used when we applied for the building permit. At the same time, the building department needs to know the window sizes in order to check whether the building satisfies various codes, including energy, fire protection, and natural light. To satisfy the requirements, we indicated the maximum and minimum possible window dimensions, with the understanding that the eventual windows would fall within that range.
At the time, it was a bit of a test with the building department. The municipality agreed with the method, and it has since become a strategy on many of our projects. The building officials are now discussing how to incorporate this type of strategy as a general principle for building regulations.

[Window inventory and elevation studies for the Zinneke office in Brussels, graphics by Ouest Architecture, Rotor and Zinneke]

What other challenges need to be overcome during the design and construction process?

MG: Some components require agreement among many different parties, and the HVAC system at Zinneke is a good example. The ventilation unit was salvaged from another project where it was only four or five years old.
This one system required several groups to reach agreement simultaneously. The building owner where the unit came from had to decide whether to sell or give away the materials. The demolition contractor had to be involved, as well as the general contractor for the new space. The maintenance company verified the condition of the system. The engineers for the new project had to approve it, as did the transport company for liability reasons. The client was there, and of course Rotor was there.
So, for this single component, eight different groups had to be at the table together to coordinate.

[Zinneke workshop in Brussels]

When coordinating with a building owner, how do you decide whether something should be given away versus paying for the salvaged item?

MG: We navigate these discussions through what we call a reclamation audit. When a building is scheduled for demolition, Rotor performs a site visit and lists all items with potential for reuse. This results in a contextual study that documents the quantity and condition of components.
We then lead an informed discussion with the owner about which materials have strong resale potential and which do not. We also rank each item by how labor-intensive it is to salvage. A component that is easy to dismantle and has market value may generate a profit for the owner, while a small item that requires significant labor and has low demand is more likely to be given away. Every component is ranked with a star system in the audit.

[Salvaged windows from the former CBR Headquarters in Brussels at the Rotor DC warehouse]

How do you deal with specifications of your design projects when inventory is always changing?

MG: We build flexibility into specifications. We’ve developed recommendations for public procurement that allow reuse, for example, specifying criteria ranges rather than exact products, or defining dimensional limits instead of fixed components.

CG: Risk is reduced by fixing certain parameters and leaving others open. Professional resellers are important partners because they understand their inventory and can provide quality assurance.
The products in our warehouse are documented in books that illustrate the range of brands and models, dimensions, colors, condition, and everything else needed to fit them into projects. These books are then delivered to design teams and general contractors.

[Tile samples in the Rotor DC specification book]

How are you disseminating information and educating the public about the circular economy?

CG: The Interreg program we mentioned earlier is a valuable platform for connecting with other cities, public authorities, and businesses across Europe, enabling the exchange of knowledge that is essential to advancing circular practices. In addition, we are frequently invited by developers, municipalities, and companies to share our experiences – sometimes through short talks and other times through in-depth workshops that span several days.

Have there been any projects of particular public interest in Rotor DC’s history?

MG: Yes. Years ago, we worked with the city of Antwerp on the restoration of one of their historic government buildings. Because the original structure dated from the 1600s, all of the 19th-century woodwork had to be removed—it was simply too recent for the requirements of the restoration.
Suddenly we had all of this beautiful carved wood and first-growth oak in our warehouse, and many visitors from Antwerp began coming to see it.

In the ecosystem of the circular economy, are there any groups that are missing in order to complete the industry?

MG: One important gap is better ways to test materials and components. There is a real need for lighter and cheaper testing methods that still provide reliable information. This is an industry that needs to scale up, while other parts—like the concrete industry—need to scale down.
Concrete production and its CO₂ emissions remain the primary barrier. You can make significant progress in the circular economy, but we’ll never truly compete as long as the concrete industry operates as it currently does.

How can this business model be successfully translated to other countries and cities?

MG: Rotor DC worked because it grew out of Rotor’s existing reputation and relationships. It helped to first establish the non-profit entity to build a reputation and establish those relationships before establishing the commercial side of the business.

CG: Trust and networks are essential. You can’t arrive in a city and immediately operate this way—it requires local knowledge and long-term relationships. Also, the cheaper the physical space is to buy or rent, the more storage capacity the business can have, which is very important for the resale model.

[Salvaged doors being loaded at the Rotor DC material yard in Brussels]

What advice do you have for architecture schools?

MG: Visit salvage dealers and get a sense of the business from the ground. Realize that the future of circular economy design will require architects to first understand the available kit of parts to consider for a project.

CG: Spend time on site. Understand the real needs of construction and circularity before designing.

The full portfolio of Rotor photos can be viewed here.