An element is a generalization of all components that make up an AEC product. Elements are physically existent objects, although they might be void elements, such as holes. Elements can be either assembled on site or pre-manufactured and built in on site.

• EXAMPLE: Examples of elements in a building construction context are walls, floors, windows and recesses.

The elements can be logically contained by a spatial structure element that constitutes a certain level within a project structure hierarchy (site, building, storey or space). This is done by using the IfcRelContainedInSpatialStructure relationship. An element can have material and quantity information assigned through the IfcRelAssociatesMaterial and IfcRelDefinesByProperties relationship. 

In addition an element can be declared to be a specific occurrence of an element type (and thereby be defined by the element type properties) using the IfcRelDefinesByType relationship. An element can also be defined as an element assembly that is a group of semantically and topologically related elements that form a higher level part of the AEC product. Those element assemblies are defined by virtue of the IfcRelAggregates relationship.

• EXAMPLE: Examples for element assembly are complete Roof Structures, made by several Roof Areas, or a Stair, composed by Flights and Landings.

Elements that performs the same function can be grouped by an "Element Group By Function". It is realized by an instance of IfcGroup with the ObjectType ='ElementGroupByFunction'. 

changes 

• IFC4 changes:
  • Name of the inverse attribute HasPorts changed to IsInterferedByElements.
• Type of the inverse attribute HasPorts changed from "SET OF [0:?] IfcRelConnectsPortToElement FOR RelatedElement" to "SET OF [0:?] IfcRelInterferesElements FOR RelatedElement".