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OpenCirc, bSDD, and IFC 4x3: How We Get Denmark to Speak the Same BIM Language

Climate requirements, LCA, building regulations, product passports, and building logbooks generate enormous amounts of data, but without a common language, they become impossible to use in practice.

With OpenCirc, bSDD, and IFC 4x3, we now have a very concrete opportunity to clean up the language – and make it easy to connect regulatory data, material passports, and BIM models. One of the best examples is the new Table 6 dictionary in bSDD, which translates the Danish LCA requirements directly into BIM.

What Is bSDD – and Why Is It Important?

bSDD (buildingSMART Data Dictionary) is an online collection of data dictionaries that describe concepts in the built environment: classes (e.g., "Duct", "External wall") and properties (e.g., "Diameter", "FireRating").

Some key points:

  • bSDD contains definitions, not project-specific data.

  • The content is published by independent organizations – e.g., standardization bodies, universities, industry organizations, and manufacturers.

  • The dictionaries can describe classes, properties, relations, mappings, translations, etc.

  • bSDD is used as a reference library in IFC models, IDS specifications, and other data standards.

  • Each definition receives a stable URI that does not change once it is active – new versions get new URIs.

In short: bSDD gives us a place where the entire industry can look up: "What exactly do we mean by this wall type, this property, this classification?" – and use the same definition across software.

Table 6 – The LCA Requirements from the Building Regulations as a Data Dictionary

In Denmark, the building regulations require climate calculations (LCA) for new buildings. The official list of which building components must be included is in BR18, Appendix 2, Table 6 – "Building components for calculation of climate impact".

This has now been elevated from a "dumb table" to a machine-readable data dictionary in bSDD:

  • Dictionary: br18B2T6

  • Organization: Technical University of Denmark (dtu.construct)

  • Version: 1.1.1

  • URI:
    https://identifier.buildingsmart.org/uri/dtu.construct/br18B2T6/1.1.1

The dictionary contains, among other things:

  • 587 classes – each representing a type of building component in Table 6

  • the property KlimapåvirkningBe18Tabel6 (br18P297stk4), which is a boolean (either-or):

    • TRUE = the building component must be included in LCA

    • FALSE = exempted

The definition directly states that the property corresponds to the requirements in BR18 §297, para. 4, and that the table is implemented as a property set that marks whether a building component should be included in the climate calculation or not.

This means you can now point to precisely the same definition in all BIM models, calculation tools, and material passports, instead of each actor "inventing" their own variant.

Mapping to IFC 4x3 – One Common BIM Ontology

Having Table 6 in bSDD is only the first step. The crucial part is that the dictionary is mapped to IFC 4x3 – the latest version of the open BIM standard.

Simplified, one can say:

  • Each Table 6 class in bSDD can be linked to one or more IFC classes (e.g., IfcWall, IfcSlab, IfcBeam, IfcRoof, IfcDoor …)

  • The property KlimapåvirkningBe18Tabel6 can be used in an IFC property set (Pset) or as a reference from an IFC object to the bSDD URI

  • An IFC 4x3 model can thus unambiguously mark whether a given building component is covered by the LCA requirement.

The result is that:

The BIM model becomes the supporting ontology, and bSDD delivers the semantics.

When we say that IFC is a superior ontology when used correctly, this is precisely what we mean:

  • IFC describes the building's spatial and technical structure (walls, slabs, installations, zones, systems)

  • bSDD describes the meaning of classes and properties

  • Mapping between IFC and bSDD binds it all together in one semantic whole.

With the Table 6 dictionary, Denmark gets a common, machine-readable understanding of "which building components count in the climate accounting" – and it can be used directly in IFC models across software and projects.

Where Does OpenCirc Fit In?

OpenCirc is built to be the material passport infrastructure for the circular economy in construction. When we connect OpenCirc to bSDD and IFC, we get three strong building blocks:

  1. IFC 4x3 – the structure for the building (the BIM ontology)

  2. bSDD – the vocabulary (classes, properties, relations)

  3. OpenCirc – the material passport layer that makes data about materials and components accessible throughout the building's lifetime.

OpenCirc + bSDD

OpenCirc is integrated with bSDD via the official bSDD API. This means that:

  • Material passports in OpenCirc can reference bSDD definitions directly (e.g., Table 6 classes and KlimapåvirkningBe18Tabel6)

  • OpenCirc can fetch property definitions, translations, and mappings from bSDD

  • All actors – from consultants to demolition contractors – work with the same concepts, regardless of which tool they use.

OpenCirc + IFC 4x3

When a project already has an IFC 4x3 model, OpenCirc can:

  • Read the IFC model and see which objects are linked to Table 6 definitions via bSDD URIs

  • Connect these objects to corresponding material passports in OpenCirc

  • Support LCA, circularity analyses, reuse scenarios, and documentation directly at the building component level.

In other words:

IFC tells where the building component is.
bSDD tells what it is.
OpenCirc tells what it consists of, and what we can do with it.

Why Is This Important for Denmark?

Denmark has (perhaps the world's most) ambitious climate requirements and a strong focus on digital construction. But without a common BIM language, we risk that:

  • Each consultant creates their own property names

  • Each client demands their own data structures

  • Each software solution uses its own codes

  • Climate calculations and material passports become manual and expensive to maintain.

The Table 6 dictionary in bSDD, mapped to IFC 4x3 – and used by OpenCirc – is a concrete step toward:

  • National semantic alignment of BIM data

  • Automatic identification of which building components are covered by LCA requirements

  • Connection between regulation and practice – from the building regulations text to data in the model

  • Better quality in material passports, because they reference the same definitions as the BIM model.

When more Danish actors – consultants, software vendors, clients, manufacturers – begin to use the same bSDD definitions and IFC mapping, we will in practice get:

A Denmark that speaks the same BIM language.

OpenCirc as a Guarantor for Data Longevity

bSDD ensures that definitions and URIs do not disappear: active definitions are immutable, and new versions are created as new objects. OpenCirc builds on this thinking, but with a focus on the material passport data itself:

  • Designed to live as long as the building

  • Open source and open data models (MIT / Creative Commons)

  • No lock-in to any particular platform or vendor

This means that:

  • Data about materials, climate impact, disassembly, and recycling are still available when the building needs to be renovated or demolished in 30–80 years

  • The digital traces can be read by future systems because they are built on open standards (IFC, bSDD, open APIs).

What Is the Next Step?

If you:

  • Work with LCA and climate requirements

  • Develop BIM tools or data platforms

  • Are a client, facility manager, or manufacturer

  • Or are simply curious about digital circularity

… then now is the time to take a closer look at:

  • bSDD Table 6 dictionary (br18B2T6)

  • IFC 4x3 as the primary BIM ontology

  • OpenCirc as the material passport layer and integration engine

OpenCirc is open source, and we invite both developers, practitioners, and researchers to participate – through code, use cases, pilot projects, data dictionary work, and everything in between.

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