What Goes in a Passport

Every passport starts with the three fields nobody argues about - identity, quantity and location - because without them there is nothing to hang anything else on. They sound trivial. They are not, and getting them right at the level of a whole building is most of the work.

What it is - identity - is more than a name. 'Steel beam' is nearly useless to a recoverer; 'S355 universal beam, 305x165, hot-rolled section, product reference and manufacturer' is actionable, because it tells an engineer what they are dealing with and lets them decide whether re-qualification is even plausible. The right level of identity is the level at which the material could be recovered and reused as a unit: a whole window unit, a specific brick type, a batch of insulation with a known specification. Too coarse and the record is vague; too fine and it becomes unmaintainable. Choosing the right granularity is a design decision, not a clerical one.

How much - quantity - is what turns a passport from a description into an asset register. A recoverer, a valuer or a city-scale urban-mine map needs numbers: twelve beams, 3.9 tonnes of steel, forty thousand bricks, so many square metres of a given cladding. Quantity is what lets anyone judge whether recovery is worth the effort and lets materials be aggregated across a building or a district into meaningful stocks. It is best expressed in units that survive - mass and count - because these are what a future market trades in.

Where - location - is the field most often underrated and most often the reason a passport fails in practice. A material you cannot locate is a material you cannot recover; 'somewhere in the east wing' is not a location. Good location data ties each entry to a real position in the building - a grid reference, a level, a room, ideally a link back to the model or a physical tag - so that decades later someone can walk to the material rather than hunt for it. Location is also what makes a passport spatial: it is the difference between a spreadsheet of stuff and a map of a material bank you can navigate. Get identity, quantity and location right and you have a genuine inventory; get them vague and everything built on top inherits the vagueness.

An inventory tells you a material exists; the next layer tells you whether it can be trusted enough to reuse. This is where properties, composition and toxicity come in - and where a passport starts to do work an ordinary asset list cannot.

Properties are the performance facts a future user needs to judge fitness for reuse: the grade and strength of a structural member, the fire rating of a partition, the thermal performance of insulation, the load rating of a floor, the durability of a finish. Crucially, properties should point to evidence, not just assertions - the grade certificate, the test data, the original specification - because reuse of anything that matters structurally will hinge on being able to re-establish those properties, and a claimed grade with no supporting record is far weaker than one backed by traceable test data. The passport does not certify the property; it records it and points to the evidence, so that an engineer later has something to work from rather than starting blind.

Composition - what the material is actually made of - matters for two reasons. First, recovery: a material you can identify as a single, clean substance (solid timber, mono-material steel, a known polymer) is far more recoverable than a bonded composite whose layers cannot be separated. Recording composition surfaces exactly the bonded-composite problem that Module 2 warns against, at the level of data. Second, and more urgently, toxicity and hazardous content: whether a material contains anything dangerous to handle, reuse or dispose of - legacy asbestos, certain treatments and coatings, substances of concern. This is not optional detail; it is a safety field. A recoverer who does not know a material is hazardous can be harmed by it, and a hazardous material quietly reused can carry the danger into the next building. Flagging composition and toxicity honestly is one of the most important things a passport does - and one of the strongest arguments for making passports at all, because this knowledge is exactly what gets lost over decades.

Together these fields answer the recoverer's real question, which is never simply 'what is it?' but 'can I trust it, is it safe, and is it clean enough to be worth recovering?' A passport that lists materials but leaves properties vague and toxicity blank has recorded the easy half and skipped the half that decides whether reuse is safe or even legal - decisions that, as ever, belong to qualified engineers, certified testing and the governing codes, with the passport there to inform them, not replace them.

The core inventory and the property fields describe a material well enough to appreciate it. Three further families are what make a passport actually circular - what turn a good description into an instruction for recovery: fixings and recoverability, provenance, and the end-of-life pathway.

Fixings and recoverability is arguably the field that distinguishes a circular passport from an ordinary one. It records how each material is connected to the rest of the building and, from that, whether it can be recovered whole: is the beam bolted (unbolt it and it comes out intact) or welded and encased (it comes out as scrap)? Is the flooring clipped and demountable or glued down? Are the layers separable or bonded? This field is the data-side mirror of design for disassembly: it captures, for the recoverer, exactly how to get the material out and in what condition they can expect to get it. A passport that says 'steel beam, S355, 3.9 t' but does not say 'bolted - unbolt to recover whole' has told the recoverer what treasure is there but not whether they can get to it. Recoverability is the field that connects the record to the physical act of withdrawal.

Provenance records where the material came from and what has happened to it: the original source or mill, the batch, the installation date, and any repairs or modifications along the way. Provenance does for materials what it does for art - it establishes trust and authenticity. For reuse, provenance matters because a material's history bears on its fitness: a beam of known origin and batch is easier to re-qualify than an anonymous one; a material with a documented service history is more trustworthy than a mystery. Provenance is also what lets a second-hand market price and warrant materials honestly rather than selling everything as anonymous scrap by weight.

End-of-life pathway records the intended next step for the material when the building or element reaches the end of its use: reuse first, then recycling, then, only as a last resort, safe disposal - and any specific instructions for doing each safely. This field is where the passport states its circular intent explicitly: it is the difference between leaving the fate of a material to whoever happens to be holding the excavator and having designed, and recorded, a plan for keeping it in use. Together, these three fields - how to get it out, where it came from, and where it should go - are what make a passport a tool for keeping materials in use rather than just a catalogue of what is about to become waste.

Now the discipline that matters more than the field list. Faced with all these families of data, the instinct is to capture everything about everything - and that instinct produces the passport's characteristic failure: the data dump. A data dump is a passport with thousands of rows and no trust: data entered once and never updated, keyed to nothing physical, with the hard fields (recoverability, toxicity) left blank because they were hard, generated to tick a box and then abandoned. It looks impressive and is useless, because no future recoverer will stake a recovery decision on data they cannot trust and cannot act on.

A useful passport is defined by the opposite properties, and none of them is 'has the most fields'. It is accurate - the data is right, not aspirational. It is current - maintained across the building's life, because a record that was true at handover and never touched again is a fossil, and buildings change. It is actionable - tied to real locations, machine-readable, and focused on the questions a recoverer actually asks. And it is honest about gaps - a field marked 'unknown' is more useful than a field filled with a confident guess, because the recoverer knows to verify rather than being misled. Less data, well chosen and trustworthy, beats more data nobody can act on, every time.

The practical way to avoid the dump is to design the passport backward from its purpose. Ask: what will a future recoverer need to decide whether, and how, to recover this material? Then capture the fields that answer that, at the granularity of recovery, and stop. For most materials the decisive fields are identity, quantity, location, recoverability and toxicity - the rest is valuable but secondary. Prioritising the high-value materials (the steel, the timber, the metals worth recovering) over exhaustive coverage of everything is not laziness; it is the difference between a passport someone will use and one that dies in a folder.

There is a deeper point here about effort proportionate to value. Capturing perfect data on a low-value, unrecoverable finish is waste; capturing trustworthy data on the recoverable structure is gold. A good passport is a curated, maintained, purpose-built record, not a comprehensive one - and building it well is a design skill in its own right. The measure of a passport is never how much it contains; it is whether, decades from now, someone can and will act on it. Everything binding that follows from that action - certifying a reused element, approving it under the codes, warranting it - still belongs to the engineers, the testing and the legal professionals; the passport's job is to make their decision possible, not to make it.