14 April 2022
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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
IfcBeamType.JOIST; IfcMemberType.PURLIN

 

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
IfcCoveringType.ROOFING; IfcCoveringType.CLADDING

 

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
IfcValveType_FAUCET; IfcElectricAppliance.HANDDRYER

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.


Pr_60_70_65_63 : Photovoltaic modules

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.

Pr_70_70_46_44 : Light-emitting diode (LED) lamps

IfcLampTypeEnum:

  • COMPACTFLUORESCENT
  • FLUORESCENT
  • HIGHPRESSUREMERCURY
  • HIGHPRESSURESODIUM
  • METALHALIDE
  • TUNGSTENFILAMENT

 

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.

 

  • IfcDiscreteAccessoryType
  • IfcFastenerType
  • IfcFurnitureType
  • IfcMechanicalFastenerType

 

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.