Component-based entities are given more detail through the use of the ‘PredefinedType’ attribute. This links to an enumerated list of more detailed types and forms the basis of the alignment activity between Uniclass and IFC.
However, a
series of rules were identified which have been followed to mitigate any
alignment inconsistencies.
Scenario |
Description |
1 |
The Uniclass title contains more than one IFC entity.
Pr_20_85_90_11 : Carbon steel lattice floor joists and purlins
NOTE: Such occurrences can inform a required update to the Uniclass tables.
Products v1.26, April 2022: Pr_20_85_90_10 Carbon steel lattice joists Pr_20_85_90_11 Carbon steel lattice purlins
|
2 |
Multiple IFC predefined types apply.
Pr_25_93_72_37 : Hardwood shingles
Some products can be installed in different scenarios, prompting a decision to be made from the narrowed down suggestions. |
3 |
The product is multi-functional. Pr_40_20_87_17 : Combined tap and hand dryers A decision needs to be made as to what is the primary function from the narrowed down suggestions.
|
4 |
Where there is no suitable IFC entity, IfcBuildingElementProxy.USERDEFINED is to be used.
NOTE: Within IFC4 ADD2 TC1 the entity IfcSolarDeviceType contains the PredefinedType ‘SOLARPANEL’. |
5 |
Where a predefined type could be applied but there is no suitable one within the enumerated list. IfcLampTypeEnum:
NOTE: Within IFC4 ADD 2 TC1 the PredefinedType ‘LED’ is available.
|
6 |
Where a predefined type cannot be applied. |
7 |
Where there is no predefined type associated to an IFC entity i.e. no enumerated list.
NOTE: PredefinedTypes for the above entities are available in IFC4 ADD2 TC1.
|
Many alignment outcomes create one to many relationships such as scenario 2. Providing a filtered set of possible outcomes allows the user to then make a decision based upon additional information they have.
Further information:
Find a Uniclass code: https://uniclass.thenbs.com/
Acknowledgements:
Chris Vickers, NBS
Emma Hooper, Bond Bryan Digital Ltd
Nick Nisbet, COBie & IFC Workstream Consultant for Government & Industry Interoperability Group.