IfcBuildingElementPart represents major components as subordinate parts of a building element. Typical usage examples include precast concrete sandwich walls, where the layers can have different geometry representations. In this case the layered material representation does not sufficiently describe the element. Each layer is represented by an own instance of the IfcBuildingElementPart with its own geometry description. 

The kind of building element part is further specified by a corresponding instance of IfcBuildingElementPartType, referred to by IfcRelDefinesByType. 

This concept can be applied to the following resources:

• IfcBuildingElementPartType

changes 

• IFC4 changes:
  • Supertype changed from "IfcBuildingElementComponent" to "IfcElementComponent"
  • Moved from IfcStructuralElementsDomain schema to IfcSharedComponentElements schema