IfcDistributionElement

Definition from IAI: Generalization of all elements that participate in a distribution system. Typical examples of IfcDistributionElement are (among others):

• building service elements within a heating systems
• building service elements within a cooling system
• building service elements within a ventilation system
• sanitary elements
• electrical elements
• elements within a communication network

The IfcDistributionElement is further specialized in the IFC model. Direct instantiation of IfcDistributionElement without an assigned subtype of IfcDistributionElementType provides the meaning of an distribution element proxy.

HISTORY New entity in IFC Release 1.5.

Type Use Definition

The IfcDistributionElement defines the occurrence of any HVAC, electrical, sanitary or other element within a distribution system. Common information about distribution element types (or styles) is handled by subtypes of IfcDistributionElementType. The IfcDistributionElementType (if present) may establish the common type name, usage (or predefined) type, common material, common set of properties and common shape representations (using IfcRepresentationMap). The IfcDistributionElementType is attached using the IfcRelDefinedByType.RelatingType objectified relationship and is accessible by the inverse IsDefinedBy attribute.

The assignment of types to distribution element occurrences is vital for providing the additional meaning, or ontology, of the distribution element. Many specialized type are defined in other schemas of the IFC specification.

Quantity Use Definition

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

Geometry Use Definitions

The geometric representation of IfcDistributionElement is given by the IfcProductDefinitionShape, allowing multiple geometric representation.

Local Placement

The local placement for IfcDistributionElement is defined in its supertype IfcProduct. It is defined by the IfcLocalPlacement, which defines the local coordinate system that is referenced by all geometric representations.

• The PlacementRelTo relationship of IfcLocalPlacement shall point (if given) to the local placement of the same IfcSpatialStructureElement , which is used in the ContainedInStructure inverse attribute, or to a spatial structure element at a higher level, referenced by that.
• If the relative placement is not used, the absolute placement is defined within the world coordinate system.

Geometric Representations

The geometric representation of IfcDistributionElement is defined using different geometric representation types for the various subtypes. Only general recommendations are given at the level of the supertype, further constraints are defined at the level of its subtypes.

• all occurrences of IfcDistributionElement (and its subtypes) should (whenever possible) share a representation map established by the assigned type. The geometric representation of the occurrence is then an IfcMappedItem. The IfcShapeRepresentation has:
  • RepresentationIdentifier : 'Body'
  • RepresentationType : 'MappedRepresentation'

The shared geometric representation of the distribution element type (or in some cases of the distribution element) should follow (if applicable) the the following guidelines:

• all fixtures (all non distribution flow elements, i.e. everything which is not a duct, a pipe, a cable, or a cable carrier) should be defined by an b-rep geometry. This includes also the complex flow fitting elements (e.g. Y branch or T branch) or distribution flow elements with size changes (e.g. reducer). The IfcShapeRepresentation has:
  • RepresentationIdentifier : 'Body'
  • RepresentationType : 'Brep'
    
    
• if the geometric model consistency of a b-rep shape representation can not be guaranteed (arcwise connected volume bounded by faces, each being connected, oriented, finite, closed 2-manifold), a surface representation based on open shells should be used. The IfcShapeRepresentation then has:
  • RepresentationIdentifier : 'Body'
  • RepresentationType : 'SurfaceModel'
    
    
• all "simple" distribution flow elements (general ducts and pipes) are defined by sweep geometry. The IfcShapeRepresentation has:
  • RepresentationIdentifier : 'Body'
  • RepresentationType : 'SweptSolid'
    
    
• an additional representation type for all "simple" distribution flow elements (general ducts and pipes) is the ability to have a simple line based representation. The IfcShapeRepresentation has:
  • RepresentationIdentifier : 'FootPrint'
  • RepresentationType : 'GeometricCurveSet'
    
    
• if only the analytical shape is required for which the exact interpolation between the cross sections is not required, a sectioned spine can be used.
  • RepresentationIdentifier : 'Body'
  • RepresentationType : 'SectionedSpine'
    

EXPRESS specification:

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