Why we don't like material passports
At Rotor, we have been active in the promotion of salvage and reuse of building materials in Brussels and in neighbouring regions since 2006. Over the years, we have witnessed and contributed to maturing debates on this topic, and advancing reuse practices in building projects. While reuse principles are now widely recognized and prioritized across the construction sector and by public authorities, this progress has raised concerns.
Certain terms have become ubiquitous in reuse discussions without deeper examination of their meaning, implications, or consequences for practice. Material passports is one such term, and this article examines its relevance through our empirical experience with reclamation audits1.
Where Do Material Passports Come From?
The term material passports commonly refers to a descriptive sheet that collates information about building products, detailing technical performances, manufacturer, constitutive materials, or place and date of production. Although the exact origin of this concept is difficult to trace, an early occurrence of it can be found in the 2002 bestseller Cradle to Cradle, written by Michael Braungart and William McDonough.2
While the authors do not use the exact expression material passport, they emphasize the need for clear communication about the chemical composition of specific products to organize nutrient flows effectively. Transparency is central to their call to radically transform the production industry.3
In a later article coauthored by Braungart, the notion of nutrient certificates is put forward together with that of material passports (perhaps the first occurrence of the term in scientific literature?). These certificates are defined as a “set of data describing defined characteristics of materials in products that give them value for recovery and reuse.”4
A next link in this genealogy is a 2014 contribution made by architect Steven Beckers5 to the catalog of Matière Grise, an influential exhibition on reuse in architecture. Created by Nicola Delon and Julien Choppin, architects and founders of the French practice Encore Heureux, the exhibition debuted at the Arsenal Pavilion in Paris and has toured continuously since. Its catalog captures the state of reuse discussions in Western European architecture at that time.6 Beckers advocated for the adoption of material passports in the construction industry to enable future reuse, arguing that materials without information are much harder to reuse.
However, the popularization of material passports in Western Europe, where Rotor operates, is largely due to the BAMB project (2015–2018). It was led by the Brussels environment administration and funded as part of the EU Horizon 2020 program for innovation. Material passports were central to this project, which promoted better documentation of materials—mostly new materials—installed in new buildings as a way to increase their reusability in future building transformations.
The BAMB consortium gathered universities, public authorities, and private companies. Among these was EPEA, founded by Michael Braungart, which was responsible for the Cradle to Cradle (C2C) certification scheme in the BAMB project. They define their contribution as such: “We have been describing the Materials Passports to be developed within BAMB as a concept for many years, including in peer-reviewed articles. Within BAMB we bring in the lessons learned in developing our Circularity Passports™, which show the circular value proposition of buildings, systems, products and materials of all parties involved in the value chain, which form a solid base for successful cycles, and the starting point for Materials Passports.” 7
From there on, the concept of material passports has become extremely widespread in both scientific literature and the services of various consultants in the circular economy.
One organization has acquired particular credit and impact in Europe: the Dutch company Madaster, established in 2017. It aims to develop a large-scale digital database of material passports from multiple buildings, including at city scale. Its solution uses BIM principles to organize information on building components alongside specific standards aimed at facilitating interoperability. It is designed for use across all phases of a project’s lifespan, from design to asset management, sourcing of materials, online marketplace, statistical purposes, and public policymaking.
From Passe-Porte to Passeport
Of all the words that could have been chosen to describe the sets of data associated with building materials, passport is worth questioning. Its associations with biopolitical identification systems raises concerns—particularly given how rarely these implications are discussed within the circular economy sector.
A brief historical detour sheds light on this expression: In the Middle Ages, the passeporte (to pass through the door) referred to the fee that merchants had to pay to enter towns and access urban markets. Passports articulated the complex relationship between medieval towns and their hinterland—two worlds with distinct economies and regulations.8
Over the centuries, passports shifted from goods to people—while other devices emerged to track goods over borders: think of customs bills, Global Trade Item Numbers (GTINs), and parcels shipping schemes. The fundamental purpose of passports has remained the same: controlling flows between territories and jurisdictions.
The rise of passports for people throughout the eighteenth century drew criticism. French jurist Jacques Peuchet harshly criticized the “passports mania” that was taking place in the aftermath of the French Revolution, viewing passports contrary to the principles of freedom that were promoted then.9
More recently, Michel Foucault and sociologist Alain Desrosières have shown how passports were instrumental in the rise of biopolitical regimes and, more broadly, government models based on population census.10
Today, passports remain a primary tool for regulating the movement of people across borders. While serving legitimate administrative functions, they are also used by governments to restrict freedom of movement. Given that thousands of people have lost their lives or their loved ones attempting to cross borders without proper documentation, it raises questions about whether this terminology is appropriate for material tracking systems, regardless of intent.
Applied to commodities such as building materials, material passports function as control systems that draw definite boundaries between what is acceptable and what is not. This raises many questions, largely unanswered to date. Which institution will be in charge of this control? Who will determine the criteria, and how? What will happen to all the materials that are present in the built environment but do not have a passport? Who will gain more power from the application of material passports, and, reversely, who will see their capacity limited? At Rotor, we are uncomfortable with the implications of these questions.
Besides the conceptual limits, the passport metaphor also shows practical limits. By definition, a passport derives its validity from being issued by a single, centralized authority, whereas our experience has shown that collecting information about existing materials only works when involving multiple voices over an iterative process. For all these reasons, we avoid using the concept of material passports in our daily work and public communication.
Keeping the Reuse Potential Alive
We stand behind the principle of collecting information about materials to enable their salvage and reuse. One practice that supports this is through “reclamation audits", which Rotor has been conducting for years in hundreds of buildings of different scales throughout Europe.18
The general approach is always the same: site visits that include documentation through photography, and collection of information about materials scheduled for removal. We compile our conclusions into an illustrated report containing a catalog of the identified materials, an assessment of their reuse potential, and suggestions for reuse pathways. These catalogs often contain detailed sheets highlighting the most promising materials alongside a table of quantities.
Our approach to reclamation audits reverses the burden of proof: By default until proven otherwise, all materials that cannot be retained in the original building—which remains our priority—should be salvaged for reuse. This principle reflects the fact that most buildings we work with are slated for demolition due to exogenous factors rather than endogenous ones. In other words, buildings are not transformed because their constituent materials have seriously deteriorated, but because of desires for renewal, return on investment, or tenant changes. Many discarded materials are simply in the wrong place at the wrong time.
Yet, we do not work in Utopia. Our optimistic approach quickly faces limiting factors including contamination of materials by harmful substances, salvage costs that exceed current standards, complicated dismantling due to poorly designed assemblies, tight schedules, or lack of demand for salvaged materials. On top of these factors, we also need to account for some materials that have deteriorated due to improper use or because of time and weathering. All these factors tend to reduce—and even eliminate—the reuse potential of the audited materials.
Fortunately, other characteristics can increase reuse potential. A material is technically “easy” to salvage if it is in demand, if it is present in sufficient quantity, if the logistics of bringing it down to the ground floor are not too complex, if its reuse leads to significant environmental benefits, or if it is still in acceptable condition. If most of these “ifs” are confirmed, the reuse potential can become significant.
When conducting an audit, our task is to carefully weigh these factors to identify reusable materials, and make sure that they will effectively be reused. This can entail many adaptations to usual workflows, such as salvaging them apart from the rest of waste flows, making sure they are properly stored, or scouting possible destinations. Weighing these factors is challenging. It requires empathy for the materials and a lot of imagination to envision their extended life, while remaining realistic about logistics and planning for any worst-case scenarios that would jeopardize the whole operation. Conducting these audits can be tedious—especially in large-scale buildings where monotony is a characteristic of the architecture. It is also deeply emotional, since our analysis has a strong influence on the materials’ destiny, and requires a lot of skill and know-how.
To a large extent, determining the reuse potential of a material is a self-fulfilling prophecy, or a performative utterance, to use J. L. Austin’s concept.19 Affirming that something is reusable makes that reality happen. It is, at minimum, a precondition for triggering the chain of actions that will lead to the materials being reinstalled in a new location—and eventually moved again in a future iteration.
However, before a material is actually reused, its “reusability” remains a fragile property. The reuse potential is not an intrinsic quality of a material. It is a consistently negotiated process, opening a dialogue with the context and with several contingent and changing aspects. In practice, the reuse potential of a given material will constantly be tested against many factors including accidents during its unmounting, transport, storage.
Collective Knowledge
Thus, reuse potential is not a static property. It is also not a totally unilateral decision. In practice, the collecting of information about materials is both iterative and collective.
Knowledge about materials is consolidated through successive phases, involving many additional parties. If one site visit allows us to collect a lot of information about materials, we often complement it with documents found in archives or in prior audits (those conducted to detect harmful substances, for instance). In this sense, the reclamation audit connects us to previous specifiers and other construction experts.
For many materials, the reuse potential strongly depends on how they were originally installed. To confirm whether their salvage is viable or not, dismantling tests often need to be carried out. These are usually undertaken by salvage specialists, who help us to refine the content of the reclamation audits by sharing their own experience with materials and advising us on the best method to salvage them. Similarly, in later stages, some materials may need laboratory testing to assess whether they remain fit for a specific use. This creates new connections with additional parties. In general, designers of the new projects also play a crucial role; their decisions can open up worlds of possibilities in terms of reusing existing elements. They need to be brought on board as soon as possible, and our reclamation audits are usually a good starting point.
In summary, the characterization of reusable materials is best thought of as a process taking place over a longer trajectory involving many different parties. These findings call for a more committed engagement in building collective knowledge about the materials that shape our built environment.
1 This text is adapted from a contribution to a seminar organized on 11 April 11, 2024, by the Faculty of Architecture of Liège University (Belgium), “‘URA Dialogues #4: Material Passport. Which Data to Make It a Real Support for Reuse?”’
The text was published in Room One Thousand in 2026, for which it was edited by Jacqueline Zhao.
2 William McDonough and Michael Braungart, Cradle to Cradle: Remaking the Way We Make Things (North Point Press, 2002).
3For a reading of why this call often falls short when applied in practice, see Lionel Billiet, Michaël Ghyoot, and Maarten Gielen (Rotor), “La plaque de plâtre et le cerisier” [On Plasterboard and Cherry Trees], Criticat, no. 9 (March 2012): 102–13. A shorter version of this text has been translated into English in the journal A+U 499, no. 12:04 (April 2012): 94–99.
4Katja Hansen, Michael Braungart, and Douglas Mulhall, “Resource Re-Pletion: Role of Buildings. Introducing Nutrient Certificates a.k.a Materials Passports as a Counterpart to Emissions Trading Schemes,” in The Springer Encyclopedia of Sustainability Science and Technology Meyers, ed. Robert A. Meyers, July 2012, https://doi.org/10.1007/978-1-4419-0851-3_420.
5Beckers was an important relay for C2C ideas in Belgium and more largely in Europe. He was close to Michael Braungart, and he founded a consultancy company, Lateral Thinking Factory (established in 2011), which contributed to popularizing many concepts of the circular economy.
6Rotor was also a contributor to the catalog. See Lionel Billiet and Michaël Ghyoot (Rotor), “La brique belge de réemploi” [Belgian reclaimed brick], in Matière grise, ed. Nicolas Delon and Julien Choppin, Matériaux / Réemploi / Architecture, Paris: Pavillon de l’Arsenal, 2014, 205–10.
7See https://www.bamb2020.eu/epea/.
8Lewis Mumford, The City in History: Its Origins, Its Transformations, and Its Prospects (Harcourt, Brace and World, 1961).
9Jacques Peuchet, Encyclopédie méthodique. Jurisprudence. Tome dixième, contenant la police et les municipalités (Paris: chez Panckoucke, Libraire, 1791), 621. The quote is worth citing in full: “It is during these unfortunate times that we mostly live in that this passport mania has made astonishing progress. With all the fuss about human rights and oaths to die for freedom, who would have thought that one does not even have the freedom to travel twenty leagues without stupid formalities, or to leave the kingdom unless one is a trader or a foreigner?” (my translation).
10Michel Foucault, Security, Territory, Population: Lectures at the Collège de France, 1977–1978, ed. Michel Senellart. trans. Graham Burchell (Palgrave MacMillan, 2008). And, by the same, The Birth of Biopolitics: Lectures at the Collège de France, 1978–1979. See also Alain Desrosières, The Politics of Large Numbers: A History of Statistical Reasoning (Harvard University Press, 2010).
11Luc Boltanski and Arnaud Esquerre, Enrichment: A Critique of Commodities, trans. by Catherine Porter (Wiley, 2020 [2017]).
12Jeanne Guien, Le désir de nouveautés. L'obsolescence au cœur du capitalisme (XVe–XXIe siècle) [The desire of newness. Obsolescence at the heart of capitalism (15th–21st century)] (La Découverte, 2025).
13See Lionel Devlieger, Livia Cahn, and Maarten Gielen (Rotor), Behind the Green Door: A Critical Look at Sustainable Architecture Through 600 Objects (Oslo Architecture Triennale, 2014); Michaël Ghyoot and Tom Schoonjans (Rotor), “Break the Cycle: The Limits of Circular Construction,” Architectural Review 521, May 2025.
14David Edgerton, The Shock of the Old: Technology and Global History Since 1900 (Profile Books, 2008); Jean-Baptiste Fressoz, More and More and More: An All-Consuming History (Penguin Books, 2025).
15On dismantling, see Emmanuel Bonnet, Diego Landivar, and Alexandre Monnin, Héritage et fermeture. Une écologie du démantèlement [Heritage and closing. An ecology of dismantling] (Divergences, 2021); Les Soulèvements de la Terre, Premières Secousses [The Earth Uprisings Collective, First Jolts] (La Fabrique, 2024).
16J. B. Fressoz, More and More and More.
17Entangled Matter was the title of our last exhibition, presented at Bozar, Brussels, between October 2024 and January 2025. See https://rotordb.org/en/projects/entangled-matter.
18During a collaboration with UK-based reuse pioneering organization Salvo, we were presented a very early version of a reclamation audit conducted in 1995. The vocabulary used to refer to this process varies from region to region. It is sometimes called a “salvage assessment,” “an inventory of reusable materials,” a “diagnosis,” a “pre-demolition audit.” Searching for and collecting information about salvaged materials is also a central aspect at RotorDC’s, a spin-off company that we launched in 2016 that specializes in selling salvaged building components and furniture. In their case too, information is paramount to bring materials back to the market. See https://rotordc.com.
19John Langshaw Austin, How to Do Things with Words: The William James Lectures Delivered at Harvard University in 1955 (Harvard University Press, 1962).