The buildingSMART Data Dictionary (bSDD) is an online service that hosts classification systems, properties and their definitions from many publishers in one place, with a common structure and an API. Software can look up a class ("external wall") or a property ("thermal transmittance") with its definition, data type, units and allowed values, instead of every project inventing its own.
At a glance
| Run by | buildingSMART International |
| Contains | Dictionaries from many publishers: IFC itself, Uniclass, ETIM, national and company dictionaries |
| Access | Web search and a public API |
| Used by | Authoring tools, IDS editors, checkers, product data platforms |
| Related standards | ISO 12006-3 (the data dictionary framework), ISO 23386 and 23387 |
What a dictionary holds
| Concept | Example |
|---|---|
| Class | Fire door, centrifugal pump, a Uniclass product code |
| Property | Fire resistance, nominal flow rate |
| Property details | Definition, data type, unit, allowed values, IFC mapping |
| Relations | Class A is a kind of class B; this class maps to IFC entity IfcDoor |
Every concept has a stable web address (URI), so models and requirement files can point to it.
How it is used
- Writing requirements: an IDS can reference bSDD properties and classes, so the meaning of each requirement is fixed.
- Authoring: plug-ins let modellers pick classifications and properties from bSDD rather than typing them.
- Product data: manufacturers describe products with the same properties that requirements ask for.
- Translation: dictionaries can hold names in several languages for the same concept.
Why it matters
Without a shared dictionary, one project's "FireRating" is another's "Fire_Resistance" and a third's "FR (min)". Checks fail, data cannot be combined and every project maps again. Referring to the same definitions removes that friction.
Limits
- The quality of each dictionary depends on its publisher.
- Not every authoring tool integrates bSDD yet.
- Project-specific properties still need definitions; projects can publish their own dictionaries.
Where to read more
Search the bSDD at search.bsdd.buildingsmart.org; buildingSMART's technical documentation describes the API and the data model.