IfcElement

Semantic definitions at the entity

Entity definition

Generalization of all components that make up an AEC product. Those elements can be logically contained by a spatial structure element that constitutes a certain level within a project structure hierarchy (e.g., site, building, storey or space). This is done by using the IfcRelContainedInSpatialStructure relationship.

Elements are physically existent objects, although they might be void elements, such as holes. Elements either remain permanently in the AEC product, or only temporarily, as formwork does. Elements can be either assembled on site or pre-manufactured and built in on site.

EXAMPLEs of elements in a building construction context are walls, floors, windows and recesses.

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.

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 may be grouped by an "Element Group By Function". It is realized by an instance of IfcGroup with the ObjectType = 'ElementGroupByFunction".

HISTORY New entity in IFC Release 1.0

Property Set Use Definition:

The property sets relating to the IfcElement are defined by the IfcPropertySet and attached by the IfcRelDefinesByProperties relationship. It is accessible by the inverse IsDefinedBy relationship. The following property set definitions specific to the IfcElement are part of this IFC release:

Pset_Draughting: common property set for elements introduced to handle the assignment of CAD related information (here layer name and object colour).
- IFC2x3 CHANGE The use of this property set is deprecated from IFC2x3 onwards, curve colours are handled by IfcCurveStyle, and layer assignment are handled by IfcPresentationLayerAssignment.
Pset_QuantityTakeOff: common property set for elements introduced to handle additional description of quantity take off.
Pset_ElementShading: common property set for elements that have shading properties to be used in energy calculations or simulations

Quantity Use Definition:

The quantities relating to the IfcElement are defined by the IfcElementQuantity and attached by the IfcRelDefinesByProperties. A detailed specification for individual quantities is introduced at the level of subtypes of IfcElement.

Geometry Use Definitions

The geometric representation of any IfcElement is given by the IfcProductDefinitionShape and IfcLocalPlacement allowing multiple geometric representations. A detailed specification for the shape representation is introduced at the level of subtypes of IfcElement.

Attribute definitions

#	Attribute	Type	Cardinality	Description	A
8	Tag	-		This attribute is out of scope for this model view definition and shall not be set.
	ConnectedTo	IfcRelConnectsElements @RelatingElement	S[0:?]	Reference to the element connection relationship. The relationship then refers to the other element to which this element is connected to.
	HasOpenings	IfcRelVoidsElement @RelatingBuildingElement	S[0:?]	Reference to the Voids Relationship that creates an opening in an element. An element can incorporate zero-to-many openings.	X
	IsConnectionRealization	IfcRelConnectsWithRealizingElements @RealizingElements	S[0:?]	Reference to the connection relationship with realizing element. The relationship then refers to the realizing element which provides the physical manifestation of the connection relationship.	X
	ConnectedFrom	IfcRelConnectsElements @RelatedElement	S[0:?]	Reference to the element connection relationship. The relationship then refers to the other element that is connected to this element.	X
	ContainedInStructure	IfcRelContainedInSpatialStructure @RelatedElements	S[0:1]	Containment relationship to the spatial structure element, to which the element is primarily associated.	X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	A
IfcRoot
1	GlobalId	IfcGloballyUniqueId	[1:1]	Assignment of a globally unique identifier within the entire software world.	X
2	OwnerHistory	IfcOwnerHistory	[1:1]	Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object, NOTE: only the last modification in stored.	X
3	Name	IfcLabel	[0:1]	Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule.	X
4	Description	IfcText	[0:1]	Optional description, provided for exchanging informative comments.	X
IfcObjectDefinition
	IsDecomposedBy	IfcRelDecomposes @RelatingObject	S[0:?]	Reference to the decomposition relationship, that allows this object to be the composition of other objects. An object can be decomposed by several other objects.	X
	Decomposes	IfcRelDecomposes @RelatedObjects	S[0:1]	References to the decomposition relationship, that allows this object to be a part of the decomposition. An object can only be part of a single decomposition (to allow hierarchical strutures only).	X
	HasAssociations	IfcRelAssociates @RelatedObjects	S[0:?]	Reference to the relationship objects, that associates external references or other resource definitions to the object.. Examples are the association to library, documentation or classification.	X
IfcObject
5	ObjectType	IfcLabel	[0:1]	The type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes. In particular it holds the user defined type, if the enumeration of the attribute PredefinedType is set to USERDEFINED.	X
	IsDefinedBy	IfcRelDefines @RelatedObjects	S[0:?]	Set of relationships to type or property (statically or dynamically defined) information that further define the object. In case of type information, the associated IfcTypeObject contains the specific information (or type, or style), that is common to all instances of IfcObject referring to the same type.	X
IfcProduct
6	ObjectPlacement	IfcObjectPlacement	[0:1]	Placement of the product in space, the placement can either be absolute (relative to the world coordinate system), relative (relative to the object placement of another product), or constraint (e.g. relative to grid axes). It is determined by the various subtypes of IfcObjectPlacement, which includes the axis placement information to determine the transformation for the object coordinate system.	X
7	Representation	IfcProductRepresentation	[0:1]	Reference to the representations of the product, being either a representation (IfcProductRepresentation) or as a special case a shape representations (IfcProductDefinitionShape). The product definition shape provides for multiple geometric representations of the shape property of the object within the same object coordinate system, defined by the object placement.	X
IfcElement
8	Tag	-		This attribute is out of scope for this model view definition and shall not be set.
	ConnectedTo	IfcRelConnectsElements @RelatingElement	S[0:?]	Reference to the element connection relationship. The relationship then refers to the other element to which this element is connected to.
	HasOpenings	IfcRelVoidsElement @RelatingBuildingElement	S[0:?]	Reference to the Voids Relationship that creates an opening in an element. An element can incorporate zero-to-many openings.	X
	IsConnectionRealization	IfcRelConnectsWithRealizingElements @RealizingElements	S[0:?]	Reference to the connection relationship with realizing element. The relationship then refers to the realizing element which provides the physical manifestation of the connection relationship.	X
	ConnectedFrom	IfcRelConnectsElements @RelatedElement	S[0:?]	Reference to the element connection relationship. The relationship then refers to the other element that is connected to this element.	X
	ContainedInStructure	IfcRelContainedInSpatialStructure @RelatedElements	S[0:1]	Containment relationship to the spatial structure element, to which the element is primarily associated.	X

Formal representations

XSD Specification

 <xs:element name="IfcElement" type="ifc:IfcElement" abstract="true" substitutionGroup="ifc:IfcProduct" nillable="true"/>

 <xs:complexType name="IfcElement" abstract="true">

  <xs:complexContent>

   <xs:extension base="ifc:IfcProduct"/>

  </xs:complexContent>

 </xs:complexType>

EXPRESS Specification


ENTITY IfcElement

 ABSTRACT SUPERTYPE OF(ONEOF(IfcBuildingElement, IfcElementAssembly, IfcElementComponent, IfcFeatureElement))

 SUBTYPE OF (IfcProduct);

  Tag : OPTIONAL IfcStrippedOptional;

 INVERSE

  ConnectedTo : SET [0:?] OF IfcRelConnectsElements FOR RelatingElement;

  HasOpenings : SET [0:?] OF IfcRelVoidsElement FOR RelatingBuildingElement;

  IsConnectionRealization : SET [0:?] OF IfcRelConnectsWithRealizingElements FOR RealizingElements;

  ConnectedFrom : SET [0:?] OF IfcRelConnectsElements FOR RelatedElement;

  ContainedInStructure : SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;

END_ENTITY;

 EXPRESS-G diagram