taxonomy - Recreate

August 17, 2026

José Hernández Vargas

Architect and PhD student at KTH Royal Institute of Technology

In an essay on the analytical language of John Wilkins, Jorge Luis Borges presents a fictional taxonomy, allegedly taken from an old Chinese encyclopaedia, which divides animals into fourteen categories: those belonging to the Emperor, embalmed ones, trained ones, suckling pigs, mermaids, fabled creatures, stray dogs, those included in this classification, those that shake like mad, uncountable ones, those drawn with a very fine brush made of camel hair, et cetera, those that have just smashed the vase, and those that resemble flies from afar. Besides its evident humour, what unsettles is the fact that the list holds together at all. The eighth category the whole scheme, category twelve abandons it, and no apparent principle joins the rest, despite each entry being intelligible on its own.

Every classification carries this risk, including the ones the construction sector relies on daily. To classify is to organise objects into classes according to criteria, and the criteria chosen determine what can subsequently be found. For precast elements recovered from buildings due for demolition, the available criteria were established for an entirely different purpose, namely the design and manufacture of new components. Reuse asks a different question of the same objects, and existing taxonomies have no place to record the answer.

From hierarchies to facets

Most construction classification systems are enumerative, that is, they attempt to list every class within a domain and arrange them in a tree. Such structures are intuitive but rigid. They accommodate objects belonging to several categories poorly, and tend to accumulate residual groups such as ‘et cetera’ in Borges’ classification. Faceted systems take the opposite approach, describing an object through several independent attributes that can be combined as required. The taxonomy proposed here is a hybrid, faceted at the top level, with each facet internally organised as an enumerative hierarchy.

Two naming conventions

For individual elements, the facets are element type, country, manufacturer and factory, production year, and a local code. The resulting string SH_SE_ABTG-STRN_1973C_ASYS-B39 reads as a hollow-core slab produced in Sweden by A-Betong at its Strängnäs factory, in a building completed in 1973, listed as B39 in the A-System catalogue. The final facet is deliberate, as it preserves the original terminology of the archives instead of overwriting it.

Naming convention for element taxonomies. Each facet is separated by an underscore, with the hyphen reserved for compound facets such as manufacturer and factory.

Systems are named through a parallel string covering structural principle, building typology, country, manufacturer, system name, and year. The Råslätt neighbourhood in Jönköping thus becomes CW_RE2_SE_ABTG-VIS_ASYS_1968C, a cross-wall system for multi-family housing.

Naming convention for system taxonomies. The facets follow the same syntax as the element codes, with structural principle and building typology replacing element type.

Both conventions distinguish the ‘blank element’ defined in a catalogue from the physical instance surveyed in a donor building, which inherits the metadata of its class and accumulates its own record of tests, defects, and interventions as it moves towards reuse.

Workflow for the classification of elements. The blank element is the type defined in a catalogue, whereas the donor building element is a surveyed instance that inherits the properties of its class and accumulates its own record of tests, defects, and interventions.

Tested against five systems

The taxonomy was applied to the Swedish A-system, the Finnish BES and LBU, the Dutch VAM, and the East German WBS-70. Reconciling them proved the most demanding part of the work. Distinctions that are unambiguous in one national context become blurred in another, and each facet had to be negotiated as a compromise between precision and usability.

Alignment with ISO 12006-2, ISO 19650, and ISO 22274 keeps the scheme compatible with existing taxonomies such as CoClass. The remaining obstacle is archival rather than conceptual. The documentation is dispersed and incomplete, and most of the manufacturers that produced these elements no longer exist. Even so, these codes now provide the indexing layer for the project’s database of reclaimed elements, the point at which a naming convention may become a searchable stock.

The full report is publicly available in the reports section.

by ReCreate project

April 14, 2026

Introduction to the report: Building, component, and connector typologies of precast concrete building systems of the ReCreate project. The full report is available here.

Erik Stenberg, KTH

What kinds of different precast concrete elements (PCE) are there out there and what do we call them?

The Recreate report D1.2 Building, component, and connector typologies of precast concrete building systems explores how precast concrete elements (PCEs) can be organized and named more effectively. To support reuse, it proposes a simple way of organizing knowledge about these elements at three different scales: 1. the building scale, 2. the component scale, and 3. the connector scale. Looking at PCEs across these scales helps describe how they relate to one another and how their physical characteristics influence reuse.

The report introduces an ordering system and naming convention for PCEs. Diagrams and short explanations show how elements behave and interact at each scale. Key diagrams summarize the main findings at three scales separately and then combined into one shared system for naming and understanding reused precast elements.

A key step in enabling reuse is understanding the material and functional characteristics of PCEs. This step is often overlooked. In this report, both quantitative data (such as dimensions and structural capacity) and qualitative aspects (such as typology or function) are analyzed at the three scales to show how they influence reuse.

At 1. The building scale, precast elements are part of a larger structural and functional system. The way elements are combined affects what kinds of buildings they can form. In turn, building types also influence which element types are suitable. For example, certain structural systems or building layouts work better with specific precast elements.

At 2. The component scale, the report examines the properties of individual precast elements. These include their form, dimensions, and historical use. Information from past building practices and Building Information Modeling (BIM) is compared to better understand typical element types and how they might be reused.

At 3. The connector scale, the focus is on how elements are joined together. The type of connection affects how easily elements can be assembled, disassembled, and reused. Some elements are more compatible with certain connectors than others.

Together, these three scales show how elements, connections, and building systems are closely linked.

The report also proposes a common nomenclature for describing PCEs across the three scales. This naming system provides basic categories for identifying and classifying elements. The typological names used in the diagrams and charts act as references that help interpret and categorize elements.

Overall, this work is an early step toward creating a taxonomy of precast building systems. This taxonomy provides a framework for classifying precast systems, elements, and structural details. In the future, it will serve as a shared knowledge base that supports the reuse of precast concrete elements and the development of digital databases of reusable building components.