BSDD (buildingSMART Data Dictionary)
Online registry of shared BIM property definitions, classifications, and values with persistent identifiers for consistent terminology across tools and teams.
Why does property naming matter in IFC models?
The IFC standard specifies the file format and defines the core entity types (Wall, Slab, Door, Property) that all software must use. But it does not mandate what you call a property, or what values are allowed. Two teams working on the same building can model it in perfectly valid IFC and still be unable to check whether they mean the same thing. Architect A labels a property FireRating, structural engineer B uses Fire_Rating, and a MEP specialist in Slovakia writes Poziarna odolnost. The model parses. No syntax error. But now the property is unstandardized: a tool cannot check it, a consultant cannot trust it, and a future user cannot reuse it without guessing.
This is the gap that bSDD fills. It is the persistent, machine-readable dictionary that lets a property in a model point to one canonical definition instead of relying on local spelling conventions.
What does the buildingSMART Data Dictionary actually contain?
A bSDD dictionary is a structured collection of definitions for concepts used across building and construction work. Each entry has a persistent identifier (a stable URL or code), a definition in multiple languages, and metadata about how that concept relates to others. A dictionary entry typically includes:
| Element | Purpose |
|---|---|
| Property definition | Name, description, and semantic meaning of a property (e.g., ThermalTransmittance) |
| Allowed values | Legal or typical values for that property, with constraints |
| Units | The measurement units the property uses (W/(m²K) for U-value) |
| Classifications | How a concept fits into broader systems (e.g., thermal performance, fire safety) |
| Relations | Links between related properties, alternate names, and dependencies |
A property entry for ThermalTransmittance might specify that the allowed unit is W/(m²K), that it applies to building elements, and that it is related to energy performance. A value entry specifies what range of U-values is legal or typical for different material types. When your model tags an element with this persistent ID instead of a local property name, any tool or consultant can look up exactly what was meant.
Who publishes and maintains bSDD dictionaries?
buildingSMART International maintains core dictionaries for widely used concepts. But bSDD is designed as a decentralized ecosystem: manufacturers can publish product-specific dictionaries (e.g., a window vendor publishes a dictionary of glazing properties and technical specifications), and national bodies or local organizations can maintain national or domain-specific dictionaries alongside them. All dictionaries share the same persistent-identifier system, so a reference to a Swedish national dictionary and a German national dictionary resolve to the same underlying concept through the master registry.
| Dictionary Type | Maintained By | Scope |
|---|---|---|
| buildingSMART core | buildingSMART International | General building concepts, IFC entity properties, common classifications |
| Manufacturer dictionaries | Vendors, product makers | Specific product lines, materials, technical specifications |
| National dictionaries | National standards bodies, local practices | Local building codes, terminology, regulatory requirements |
| Domain dictionaries | Specialist organisations (energy, safety, conservation) | Niche concepts not in general use |
This approach allows a small Slovak practice to reference Czech, German, or English dictionaries seamlessly, while also supporting local terminology when it exists.
How does bSDD pair with IDS for model validation?
bSDD and IDS solve complementary problems. IDS (Information Delivery Specification) defines what data must be present in a model at a given stage: this wall must have a FireRating property, and this slab must include a Thickness property. But IDS is written in a shared vocabulary. Without bSDD, an IDS requirement is only as portable as the local naming convention. If your model uses Fire_Rating instead of FireRating, the IDS check fails, even though you have the information. bSDD provides the canonical vocabulary so that an IDS check can say this property must be present, and it must resolve to bSDD definition XYZ, not this must be spelled exactly as FireRating. This makes model checks portable across teams and borders.
Why does bSDD matter for multilingual and cross-border teams?
One identifier can carry multiple language labels. A property in bSDD can be published with an English definition, a Slovak label, a Polish label, and a German label, all pointing to the same persistent concept. When your model references that definition ID, a Slovak consultant, an English architect, and a Czech engineer can all see the property in their working language without re-translating or re-defining. The same definition ID works everywhere. This is essential for residential and sustainability projects where cross-border collaboration is common. A Slovak practice working with Austrian or German consultants on a passive-house project benefits immediately: shared thermal properties, airtightness data, and construction classifications resolve to the same meaning in every language. The alternative is manual translation in every handoff, which introduces transcription errors and delays.
What are the current limits of bSDD?
bSDD is powerful but has honest limitations. Coverage is uneven. English and core construction terms are well represented; specialized or emerging topics are sparse. A published dictionary is only as good as its maintainer, and if a dictionary is not updated, definitions fall out of sync with practice. Slovak-language coverage is particularly thin: while buildingSMART publishes some content in Slovak, many dictionaries are English-only or German-first. As a result, much practical work in Slovakia still defaults to English property names, with Slovak labels applied only where a translation already exists. The standard exists to eliminate this friction, but adoption requires critical mass. A solo practice cannot unilaterally impose bSDD terminology; you can only benefit from it when your consultants and software also support it. For now, treating bSDD as an aspirational target rather than a mandate is realistic.
Frequently asked questions
- Do I need to use bSDD on every project?
- Not yet. bSDD adoption is voluntary on most residential projects, but required or strongly expected on EU public-procurement work and large openBIM workflows. For solo practices, bSDD matters most when consulting with partners who use it, or when model handover needs to survive beyond the originating software's lifecycle.
- What is the difference between bSDD and IFC?
- IFC is the file format and entity data model; bSDD is the shared vocabulary service that defines what property names, values, and units mean. IFC lets you exchange a model; bSDD lets you check it reliably because everyone agreed on terminology.
- Can a small residential practice benefit from bSDD?
- Yes, if you work with structural engineers or MEP consultants using different software, or if you hand models to foreign consultants. The biggest benefit is reduction of transcription errors and rework when property definitions are mismatched between disciplines. For entirely in-house work in one tool, the benefit is less immediate.
- How do I actually access and use bSDD dictionaries in my work?
- Most users access bSDD indirectly: your BIM software vendor may integrate lookups, or you use it at handover to validate what was exported. The dictionaries are free online at www.bsdd.buildingsmart.org. You reference a definition via its persistent ID (a URL or unique code) in your model metadata or documentation.
- What happens if a property I need is not published in any bSDD dictionary?
- You can define it locally and document it explicitly, but it will not be portable to other software or teams without re-definition. This is common in specialized or early-stage work. If the property becomes standard practice, it can be submitted for inclusion in a dictionary maintainer's next release.
- Is there a complete Slovak-language bSDD dictionary available?
- Not yet. buildingSMART publishes core dictionaries in multiple languages including Slovak, but coverage is uneven and lags behind English. Most practical work in Slovakia still uses English property names, with Slovak labels applied locally. This is one honest limit of the current ecosystem.