Approvals may be associated to indicate the status of acceptance or rejection using the IfcRelAssociatesApproval relationship where RelatingApproval refers to an IfcApproval and RelatedObjects contains the IfcActionRequest. Approvals may be split into sub-approvals using IfcApprovalRelationship to track approval status separately for each party where RelatingApproval refers to the higher-level approval and RelatedApprovals contains one or more lower-level approvals. The hierarchy of approvals implies sequencing such that a higher-level approval is not executed until all of its lower-level approvals have been accepted.

As shown in Figure 1, an IfcActionRequest may be aggregated into components.

Figure 1 — Action request composition

Cost schedules may indicate the costs projected or incurred for the request.

A request may be nested into follow-up requests, in order of issue

As shown in Figure 1, an IfcActionRequest may be assigned to the following entities using relationships as indicated:

• IfcActor (IfcRelAssignsToActor): Person or organization issuing the request such as a tenant or owner.

The IfcActionRequest may have assignments of its own using the IfcRelAssignsToControl relationship where RelatingControl refers to the IfcActionRequest and RelatedObjects contains one or more objects of the following types:

• IfcActor: Person or organization(s) fulfilling the request such as a facilities manager or contractor.

Figure 1 — Action request assignment

Indicates project directives issued by the actor.

Indicates groups for which the actor is responsible.

Indicates products for which the actor is responsible.

Indicates processes for which the actor is responsible.

Indicates resources for which the actor is responsible.

Material from which the casing is constructed.

Receives signal.

Indicates a connected valve, damper, or switch controlled by the actuator.

Material from which the casing is constructed.

Supply air, typically connected from a duct segment or fitting.

Return air, typically connected to a duct segment or fitting.

Supply air, typically connected from a duct segment or fitting.

Material from which the casing is constructed.

Incoming air.

Outgoing regulated air.

Material from which the casing is constructed.

The primary media material used for heat transfer.

Conditioned air in.

Conditioned air out.

Exhausted air in.

Exhausted air out.

Material from which the casing is constructed.

Receives signal.

Any point or curve

Area for hatching

Text literal for applying text

Any point, curve or surface representing the annotation.

The operating function of an asset within an organization may be particularly valuable in situations where one organization provides and maintains core services and another organization adds and maintains terminal services. It can classify who owns and is responsible for the asset. Operating function can be designated through the use of one or more classification references.

Physical elements that comprise the asset.

Material from which the casing is constructed.

May contain IfcAudioVisualAppliance components.

Receives electrical power.

Input audio.

Audio speaker(s), which may be aggregated for separate speaker channels.

Receives electrical power.

Receives control signal.

Network access.

Captured video.

Receives electrical power.

Receives control signal.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Receives electrical power.

Captured audio.

Receives electrical power.

Receives control signal.

Rendered media content.

Receives electrical power.

Receives control signal.

Input audio/video source.

Receives electrical power.

Receives control signal.

Network access.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Output audio/video zone.

Output audio/video zone.

Audio speaker(s), which may be aggregated for separate speaker channels.

Audio speaker(s), which may be aggregated for separate speaker channels.

Amplified audio input.

Receives electrical power.

Receives control signal.

Network access.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Input audio/video source.

Output audio/video zone.

Output audio/video zone.

Output audio/video zone.

Output audio/video zone.

Output audio/video zone.

Output audio/video zone.

Output audio/video zone.

Output audio/video zone.

Receives electrical power.

Telecommunications network.

Receives electrical power.

Receives control signal.

Receives modulated data feed such as satellite, cable, or over-the-air.

Rendered media content.

The IfcBeam, as any subtype of IfcBuildingElement, may participate alternatively in one of the two different containment relationships:

• the Spatial Containment (defined here), or
• the Element Composition.

Default spatial container

Spatial container for the element if it cannot be assigned to a building storey

Spatial container for the element in case that it is placed on site (outside of building)

Special purpose composite entity

Any building element can be a composite

The material of the IfcBeam is defined by the IfcMaterialProfileSet or as fallback by IfcMaterial, and it is attached either directly or at the IfcBeamType.

NOTE  It is illegal to assign an IfcMaterialProfileSetUsage to an IfcBeam. Only the subtype IfcBeamStandardCase supports this concept.

The 'Axis' 'Curve 3D' geometry can be used to represent the system axis and length of a beam that may extent the body length.

NOTE  The 'Axis' is not used to locate the material profile set, only the subtype IfcBeamStandardCase provides this capability.

Three-dimensional reference curve for the beam.

The following additional constraints apply to the 'SweptSolid' representation type:

• Solid: IfcExtrudedAreaSolid, IfcRevolvedAreaSolid shall be supported
• Profile: all subtypes of IfcProfileDef (with exception of IfcArbitraryOpenProfileDef)
• Extrusion:  All extrusion directions shall be supported.

Figure 1 illustrates the 'SweptSolid' geometric representation. There are no restrictions or conventions on how to use the local placement (black), solid of extrusion placement (red) and profile placement (green).

Figure 1 — Beam swept solid

Figure 2 illustrates the use of non-perpendicular extrusion to create the IfcExtrudedAreaSolid.

Figure 2 — Beam non-perpendicular extrusion

The following additional constraints apply to the 'AdvancedSweptSolid' representation type:

• Solid: IfcSurfaceCurveSweptAreaSolid, IfcFixedReferenceSweptAreaSolid, IfcExtrudedAreaSolidTapered, IfcRevolvedAreaSolidTapered shall be supported.

NOTE  View definitions and implementer agreement can further constrain the allowed swept solid types.

• Profile: see 'SweptSolid' geometric representation
• Extrusion: not applicable

The following additional constraints apply to the 'Clipping' representation type:

• Solid: see 'SweptSolid' geometric representation
• Profile: see 'SweptSolid' geometric representation
• Extrusion: see 'SweptSolid' geometric representation
• Boolean result: The IfcBooleanClippingResult shall be supported, allowing for Boolean differences between the swept solid (here IfcExtrudedAreaSolid) and one or several IfcHalfSpaceSolid (or its subtypes).

Figure 1 illustrates use of IfcBooleanClippingResult between an IfcExtrudedAreaSolid and an IfcHalfSpaceSolid to create a clipped body.

Figure 1 — Beam clipping

An idealized structural member corresponding to the beam.

The IfcBeamStandardCase defines in addition that the IfcBeamType should have a unique IfcMaterialProfileSet, that is referenced by the IfcMaterialProfileSetUsage that is assigned to all occurrences of this IfcBeamType.

	EXAMPLE  Figure 1 illustrates assignment of IfcMaterialProfileSetUsage and IfcMaterialProfileSet to the IfcBeamStandardCase as the beam occurrence and to the IfcBeamType. The same IfcMaterialProfileSet shall be shared by many occurrences of IfcMaterialProfileSetUsage. This relationship shall be consistent to the relationship between the IfcBeamType and the IfcBeamStandardCase.
Figure 1 — Beam profile usage

<blockquote class="example">EXAMPLE&nbsp; Figure 2 illustrates alignment of cardinal points.</blockquote> NOTE  It has to be guaranteed that the use of IfcCardinalPointEnum is consistent to the placement of the extrusion body provided by IfcExtrudedAreaSolid.Position NOTE  The cardinal points 8 (top centre) and 6 (mid-depth right) are assigned according to the definition at IfcCardinalPointReference

Figure 2 — Beam cardinal points

	EXAMPLE  Figure 3 illustrates assignment of a composite profile by using IfcCompositeProfile for geometric representation and several IfcMaterialProfile's within the IfcMaterialProfileSet.
Figure 3 — Beam composite profiles

The following restriction is imposed:

• The local placement shall provide the location and directions for the standard beam, the x/y plane is the plane for the start profile, and the z-axis is the extrusion axis for the beam body (in case of rotation, the tangent direction).

The following additional constraints apply to the 'Axis' representation, if the 'Body' shape representation has the RepresentationType : 'SweptSolid':

• Axis
  • IfcPolyline having two Points, or IfcTrimmedCurve with BasisCurve of Type IfcLine for 'SweptSolid' provided as IfcExtrudedAreaSolid. The axis curve lies on the z axis of the object coordinate system.
  • IfcTrimmedCurve with BasisCurve of Type IfcCircle for 'SweptSolid' provided as IfcRevolvedAreaSolid. The axis curve lies on the x/z plane of the object coordinate system, the tangent at the start is along the positive z-axis.

	EXAMPLE  As shown in Figure 76, the axis shall be defined along the z axis of the object coordinate system. The axis representation can be used to represent the system length of a beam that may extent the body length of the beam.
Figure 1 — Beam axis representation

EXAMPLE  As shown in Figure 77, the axis representation shall be used to represent the cardinal point as the offset between the 'Axis' and the extrusion path of the beam. The extrusion path is provided as IfcExtrudedAreaSolid.ExtrudedDirection and should be parallel to the 'Axis' and the z axis. It has to be guaranteed that the value provided by IfcMaterialProfileSetUsage.CardinalPoint is consistent to the IfcExtrudedAreaSolid.Position.

Figure 2 — Beam axis cardinal point

The following additional constraints apply to the 'SweptSolid' representation:

• Solid: IfcExtrudedAreaSolid, IfcRevolvedAreaSolid shall be supported
• Solid Position : The IfcSweptAreaSolid.Position shall exclusively been used to correspond to the cardinal point. The x/y offset of the Position represents the cardinal point offset of the profile against the axis. No rotation shall be allowed.
• Profile: All subtypes of IfcParameterizedProfileDef
• Profile Position : For all single profiles, the IfcParameterizedProfileDef.Position shall be NIL, or having Location = 0.,0. and RefDirection = 1.,0.
• Extrusion: Perpendicular to the profile direction. The IfcExtrudedAreaSolid.ExtrudedDirection shall be [0.,0.,1.].
• Orientation: The y-axis of the profile, as determined by IfcSweptAreaSolid.Position.P[2] shall point upwards. It indicates the "role" of the beam, a role=0° means y-axis of profile pointing upwards.

Figure 1 illustrates a standard geometric representation with cardinal point applied as 1 (bottom left).

The following interpretation of dimension parameter applies for rectangular beams with linear extrusions:

• IfcRectangleProfileDef.YDim interpreted as beam height
• IfcRectangleProfileDef.XDim interpreted as beam width

The following interpretation of dimension parameter applies for circular beams:

• IfcCircleProfileDef.Radius interpreted as beam radius.

Figure 1 — Beam body extrusion

The following additional constraints apply to the 'AdvancedSweptSolid' representation type:

• Solid: IfcSurfaceCurveSweptAreaSolid, IfcFixedReferenceSweptAreaSolid, IfcExtrudedAreaSolidTapered, IfcRevolvedAreaSolidTapered shall be supported.

NOTE  View definitions and implementer agreement can further constrain the allowed swept solid types.

• Solid Position : see 'SweptSolid' geometric representation
• Profile: see 'SweptSolid' geometric representation
• Profile Position : see 'SweptSolid' geometric representation
• Extrusion: not applicable

The following constraints apply to the 'Clipping' representation:

• Solid : see 'SweptSolid' geometric representation
• Solid Position : see 'SweptSolid' geometric representation
• Profile : see 'SweptSolid' geometric representation
• Profile Position : see 'SweptSolid' geometric representation
• Extrusion : see 'SweptSolid' geometric representation
• Orientation : see 'SweptSolid' geometric representation
• Boolean result: The IfcBooleanClippingResult shall be supported, allowing for Boolean differences between the swept solid (here IfcExtrudedAreaSolid) and one or several IfcHalfSpaceSolid (or its subtypes).

Figure 1 illustrates a 'Clipping' geometric representation with use of IfcBooleanClippingResult between an IfcExtrudedAreaSolid and an IfcHalfSpaceSolid to create a clipped body, with cardinal point applied as 4 (mid-depth left)

Figure 1 — Beam body clipping

The material of the IfcBeamType is defined by the IfcMaterialProfileSet or as fall back by IfcMaterial and attached by the IfcRelAssociatesMaterial.RelatingMaterial. It is accessible by the inverse HasAssociations relationship.

NOTE  It is illegal to assign an IfcMaterial to an IfcBeamType, if there is at least one occurrence of IfcBeamStandardCase for this type.

The shared profile definition is defined by assigning an IfcMaterialProfileSet (see material use definition above). The IfcMaterialProfile refers to the subtype of IfcProfileDef that is the common profile for all beam occurrence, if used. It is only applicable if the IfcBeamType has only occurrences of type IfcBeamStandardCase (see definition of IfcBeamStandardCase for further information).

NOTE  The attribute ProfileName of the IfcProfileDef subtype, referenced in IfcMaterialProfile should contain a standardized profile name according to local standards. However, an additional geometric representation of the profile is necessary (such as IfcExtrudedAreaSolid). An importing application is allowed to check for the existence of the profile name: in case of identifying it as a standardized name, the corresponding profile geometry and possibly other cross sectional properties can be read from a library. Otherwise the geometric representation and possible non geometric IfcProfileProperties have to be used.

The IfcBeamType may define the shared geometric representation for all beam occurrences. The RepresentationMaps attribute refers to a list of IfcRepresentationMap's, that allow for multiple geometric representations (e.g. with IfcShaperepresentation's having an RepresentationIdentifier 'Box', 'Axis', or 'Body'). It is only applicable if the IfcBeamType has only occurrences of type IfcBeam (See geometric use definition of IfcBeam for further information).

NOTE  If the IfcBeamType has an associated IfcMaterialProfileSet, then no shared geometric representation shall be provided.

NOTE  The product shape representations are defined as RepresentationMaps (attribute of the supertype IfcTypeProduct), which get assigned by an element occurrence instance through the IfcShapeRepresentation.Item[n] being an IfcMappedItem. See IfcTypeProduct for further information.

NOTE  The values of attributes RepresentationIdentifier and RepresentationType of IfcShapeRepresentation are restricted in the same way as those for IfcBeam and IfcBeamStandardCase

Material from which the casing is constructed.

Gas inlet for burner.

Exhaust sent to outside.

Water feed such as from condenser.

Steam sent to heating coils and space heaters.

Gas inlet for burner.

Exhaust sent to outside.

Cold water to be heated.

Hot water heated.

An IfcBorehole may be represented by a curve in 3D space representing the drilling axis.

An IfcBorehole may be represented by a swept solid.

NOTE  By using the inverse relationship IfcBridge.Decomposes it references IfcProject || IfcSite || IfcBridge through IfcRelAggregates.RelatingObject. If it refers to another instance of IfcBridge, the referenced IfcBridge needs to have a different and higher CompositionType, i.e. COMPLEX (if the other IfcBuilding has ELEMENT), or ELEMENT (if the other IfcBridge has PARTIAL).

Direct assignment to project, if the bridgeis the outermost spatial container, and no site information is provided for bridge projects

Assignment to site, if the bridge is the spatial container for the bridge project with site information

Assignment to another bridge as spatial container, e.g. if this bridge represents a bridge section.

NOTE  By using the inverse relationship IfcBridge.IsDecomposedBy it references IfcBridge || IfcBridgePart through IfcRelAggregates.RelatedObjects. If it refers to another instance of IfcBridge, the referenced IfcBridge needs to have a different and lower CompositionType, i.e. ELEMENT (if the other IfcBridge has COMPLEX), or PARTIAL (if the other IfcBridge has ELEMENT).

Spatial decomposition into bridge parts

Spatial decomposition into other bridges, e.g. if this bridge represents a complex bridge that is subdivided into bridge sections.

NOTE  If there are building elements and/or other elements directly related to the IfcBridge, they are associated with the IfcBridge by using the objectified relationship IfcRelContainedInSpatialStructure. The IfcBridge references them by its inverse relationship: > * IfcBridge.ContainsElements -- referencing any subtype of IfcProduct (with the exception of other spatial structure element) by IfcRelContainedInSpatialStructure.RelatedElements.

Physical elements that are directly related to the building.

Annotations that are directly related to the building.

Positioning elements that are directly related to the building.

The local placement for IfcBridge is defined in its supertype IfcProduct. It is defined by IfcLocalPlacement or by IfcLinearPlacement>/em> which defines the local coordinate system that is referenced by all geometric representations.

• The PlacementRelTo relationship of IfcLocalPlacement shall point (if relative placement is used) to the IfcSpatialStructureElement of type IfcSite, or of type IfcBuilding (e.g. to position a building relative to a building complex, or a building section to a building).
• If the relative placement is not used, the absolute placement is defined within the world coordinate system.

The body (or solid model) geometric representation (if the bridge has an independent geometric representation) of IfcBridge is defined using faceted B-Rep capabilities (with or without voids), based on the IfcFacetedBrep or on the IfcFacetedBrepWithVoids. In the case of alignment based infrastructure, the geometric representation can be defined using IfcSectionedSolidHorizontal optionally IfcSweptAreaSolid.

NOTE  Since the bridge shape is usually described by the exterior building elements, an independent shape representation shall only be given, if the bridge is exposed independently from its constituting elements and such independent geometric representation may be prohibited in model view definitions.

NOTE  By using the inverse relationship IfcBridgePart.Decomposes it references (IfcBridge || IfcBridgePart) through IfcRelAggregates.RelatingObject_IfcBridgePart, the referenced IfcBridgePart needs to have a different and higher CompositionType, i.e. COMPLEX (if the other IfcBridgePart has ELEMENT), or ELEMENT (if the other IfcBridgePart has PARTIAL)._

Assignment to the bridge, where the bridge part is a part of.

Assignment to another bridge part, e.g. if this bridge part is a part that refers to another bridge part.

NOTE  By using the inverse relationship IfcBridgePart.IsDecomposedBy it references IfcBridgePart through IfcRelAggregates.RelatedObjects. If it refers to another instance of IfcBridgePart, the referenced IfcBridgePart needs to have a different and lower CompositionType, i.e. ELEMENT (if the other IfcBuildingStorey has COMPLEX), or PARTIAL (if the other IfcBuildingStorey has ELEMENT).

NOTE  Multi storey spaces shall be spatially contained by only a single building storey, usually it is the building storey where the base of the space lies.

Spatial decomposition into bridge parts, if this bridge part is a main bridge part having subdivisions.

If there are building elements and/or other elements directly related to the IfcBridgePart (like most building elements, such as walls, columns, etc.), they are associated with the IfcBridgePart by using the objectified relationship IfcRelContainedInSpatialStructure. The IfcBridgePart references them by its inverse relationship:

• IfcBridgePart.ContainsElements -- referencing any subtype of IfcProduct (with the exception of other spatial structure element) by IfcRelContainedInSpatialStructure.RelatedElements.

Elements can also be referenced in an IfcBridgePart, for example, if they span through several storeys. This is expressed by using the objectified relationship IfcRelReferencedInSpatialStructure. Systems, such as building service or electrical distribution systems, zonal systems, or structural analysis systems, relate to IfcBridgePart by using the objectified relationship IfcRelServicesBuildings.

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

• The PlacementRelTo relationship of IfcLocalPlacement or IfcLinearPlacement shall point (if relative placement is used) to the IfcSpatialStructureElement of type IfcBridge, or of type IfcBridgePart (e.g. to position a bridge part relative to a bridge part complex, or a partial bridge part to a bridge part).
• If the relative placement is not used, the absolute placement is defined within the world coordinate system.

The body (or solid model) geometric representation (if the bridge part has an independent geometric representation) of IfcBridgePart is defined using faceted B-Rep capabilities (with or without voids), based on the IfcFacetedBrep or on the IfcFacetedBrepWithVoids. In the case of alignment based infrastructure, the geometric representation can be defined using IfcSectionedSolidHorizontal optionally IfcSweptAreaSolid.

NOTE  Since the bridge part shape is usually described by the exterior building elements, an independent shape representation shall only be given, if the bridge part is exposed independently from its constituting elements and such independent geometric representation may be prohibited in model view definitions.

NOTE  By using the inverse relationship IfcBuilding.Decomposes it references IfcProject || IfcSite || IfcBuilding through IfcRelAggregates.RelatingObject. If it refers to another instance of IfcBuilding, the referenced IfcBuilding needs to have a different and higher CompositionType, i.e. COMPLEX (if the other IfcBuilding has ELEMENT), or ELEMENT (if the other IfcBuilding has PARTIAL).

Direct assignment to project, if the building is the outermost spatial container, and no site information is provided for building projects

Assignment to site, if the building is the spatial container for the building project with site information

Assignment to another building as spatial container, e.g. if this building represents a building section.

NOTE  By using the inverse relationship IfcBuilding.IsDecomposedBy it references IfcBuilding || IfcBuildingStorey through IfcRelAggregates.RelatedObjects. If it refers to another instance of IfcBuilding, the referenced IfcBuilding needs to have a different and lower CompositionType, i.e. ELEMENT (if the other IfcBuilding has COMPLEX), or PARTIAL (if the other IfcBuilding has ELEMENT).

Spatial decomposition into building stories.

Spatial decomposition into other buildings, e.g. if this building represents a complex building that is subdivided into building sections.

NOTE  If there are building elements and/or other elements directly related to the IfcBuilding (like a curtain wall spanning several stories), they are associated with the IfcBuilding by using the objectified relationship IfcRelContainedInSpatialStructure. The IfcBuilding references them by its inverse relationship: > * IfcBuilding.ContainsElements -- referencing any subtype of IfcProduct (with the exception of other spatial structure element) by IfcRelContainedInSpatialStructure.RelatedElements.

Physical elements contained in the building.

Annotations that are directly related to the building.

Grids that are directly related to the building.

The local placement for IfcBuilding 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 relative placement is used) to the IfcSpatialStructureElement of type IfcSite, or of type IfcBuilding (e.g. to position a building relative to a building complex, or a building section to a building).
• If the relative placement is not used, the absolute placement is defined within the world coordinate system.

The foot print representation of IfcBuilding is given by either a single 2D curve (such as IfcPolyline or IfcCompositeCurve), or by a list of 2D curves (in case of inner boundaries), if the building has an independent geometric representation.

NOTE  The independent geometric representation of IfcBuilding may not be allowed in certain model view definitions. In those cases only the contained elements and spaces have an independent geometric representation.

The body (or solid model) geometric representation (if the building has an independent geometric representation) of IfcBuilding is defined using faceted B-Rep capabilities (with or without voids), based on the IfcFacetedBrep or on the IfcFacetedBrepWithVoids.

NOTE  Since the building shape is usually described by the exterior building elements, an independent shape representation shall only be given, if the building is exposed independently from its constituting elements and such independent geometric representation may be prohibited in model view definitions.

The usage of building address, elevation measures and composition type is governed by this concept.

NOTE  The IfcBuildingElementProxyType can be used to share common information among many occurrences of the same proxy without establishing a particular semantic meaning of the type.

If no IfcBuildingElementProxyType is attached (i.e. if only occurrence information is available) the PredefinedType should be provided. If set to .USERDEFINED. a user defined value has to be provided by the ObjectType attribute.

The material of the IfcBuildingElementProxy is defined by IfcMaterial and attached by the IfcRelAssociatesMaterial.RelatingMaterial. It is accessible by the inverse HasAssociations relationship.

NOTE  It is illegal to assign an IfcMaterial to an IfcBuildingElementProxy with the PredefinedType = ProvisionForVoid.

Material information can also be given at the IfcBuildingElementProxyType, defining the common attribute data for all occurrences of the same type. It is then accessible by the inverse IsTypedBy relationship pointing to IfcBuildingElementProxyType.HasAssociations and via IfcRelAssociatesMaterial.RelatingMaterial to IfcMaterial. If both are given, then the material directly assigned to IfcBuildingElementProxy overrides the material assigned to IfcBuildingElementProxyType.

The IfcBuildingElementProxy, as any subtype of IfcBuildingElement, may participate alternatively in one of the two different containment relationships:

• the Spatial Containment (defined here), or
• the Element Composition.

Default spatial container

Spatial container for the element if it cannot be assigned to a building storey

Spatial container for the element in case that it is placed on site (outside of building)

NOTE  By using the inverse relationship IfcBuildingStorey.Decomposes it references (IfcBuilding || IfcBuildingStorey) through IfcRelAggregates.RelatingObject_IfcBuildingStorey, the referenced IfcBuildingStorey needs to have a different and higher CompositionType, i.e. COMPLEX (if the other IfcBuildingStorey has ELEMENT), or ELEMENT (if the other IfcBuildingStorey has PARTIAL)._

Assignment to the building, where the building storey is a part of.

Assignment to another building storey, e.g. if this building storey is a partial storey that refer to another storey.

NOTE  By using the inverse relationship IfcBuildingStorey.IsDecomposedBy it references IfcBuildingStorey || IfcSpace through IfcRelAggregates.RelatedObjects. If it refers to another instance of IfcBuildingStorey, the referenced IfcBuildingStorey needs to have a different and lower CompositionType, i.e. ELEMENT (if the other IfcBuildingStorey has COMPLEX), or PARTIAL (if the other IfcBuildingStorey has ELEMENT).

NOTE  Multi storey spaces shall be spatially contained by only a single building storey, usually it is the building storey where the base of the space lies.

Reference to the spaces that are assigned to this storey.

Spatial decomposition into partial stories, if this storey is a main storey having subdivisions.

If there are building elements and/or other elements directly related to the IfcBuildingStorey (like most building elements, such as walls, columns, etc.), they are associated with the IfcBuildingStorey by using the objectified relationship IfcRelContainedInSpatialStructure. The IfcBuildingStorey references them by its inverse relationship:

• IfcBuildingStorey.ContainsElements -- referencing any subtype of IfcProduct (with the exception of other spatial structure element) by IfcRelContainedInSpatialStructure.RelatedElements.

Elements can also be referenced in an IfcBuildingStorey, for example, if they span through several storeys. This is expressed by using the objectified relationship IfcRelReferencedInSpatialStructure. Systems, such as building service or electrical distribution systems, zonal systems, or structural analysis systems, relate to IfcBuildingStorey by using the objectified relationship IfcRelServicesBuildings.

The local placement for IfcBuildingStorey 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 relative placement is used) to the IfcSpatialStructureElement of type IfcBuilding, or of type IfcBuildingStorey (e.g. to position a building storey relative to a building storey complex, or a partial building storey to a building storey).
• If the relative placement is not used, the absolute placement is defined within the world coordinate system.

The foot print representation of IfcBuildingStorey is given by either a single 2D curve (such as IfcPolyline or IfcCompositeCurve), or by a list of 2D curves (in case of inner boundaries), if the building storey has an independent geometric representation.

NOTE  The independent geometric representation of IfcBuildingStorey may not be allowed in certain model view definitions. In those cases only the contained elements and spaces have an independent geometric representation.

The body (or solid model) geometric representation (if the building storey has an independent geometric representation) of IfcBuildingStorey is defined using faceted B-Rep capabilities (with or without voids), based on the IfcFacetedBrep or on the IfcFacetedBrepWithVoids.

NOTE  Since the building storey shape is usually described by the exterior building elements, an independent shape representation shall only be given, if the building storey is exposed independently from its constituting elements and such independent geometric representation may be prohibited in model view definitions.

Building systems may be aggregated into subsystems.

Building elements participating in the building system.

Task for operating upon the building element.

Some IfcBuildingElement may be represented by an surface as an abstract geometric representation. See each subtype for specific guidance.

Material from which the casing is constructed.

Material designed to be burned.

Gas inlet for burner.

Material from which the casing is constructed.

Head connection.

Tail connection.

Head connection.

Tail connection.

Left connection.

Right connection.

Head connection.

Tail connection.

Head connection.

Left connection.

Right connection.

Material from which the casing is constructed.

Head connection.

Tail connection.

Material from which the casing is constructed.

Material from which the conductors are constructed, such as Aluminium or Copper.

For equipotential bonding, may represent a clamp that is attached from a pipe or other conducting element of an earthing system.

For equipotential bonding, may represent a clamp that is attached from a pipe or other conducting element of an earthing system.

The input of the connector.

The output of the connector.

The output of the connector.

The input of the connector.

The input of the connector.

An output of the connector.

An output of the connector.

The input of the connector.

The output of the connector.

Material from which the conductors are constructed, such as Aluminium or Copper.

The material from which the insulation is constructed such as PVC, PEX, or EPR.

The material from which the screen that covers the sheath is constructed (mantel) such as Aluminium, Copper, Steel, or Lead.

The outer sheathing of the cable which may be color-coded.

Cable segments may be aggregated into cable cores.

Cable cores may be aggregated into cable conductors.

The input end of the cable. While many cables may be bidirectional, port direction is indicated for connectivity purposes.

The output end of the cable. While many cables may be bidirectional, port direction is indicated for connectivity purposes.

Material from which the casing is constructed.

Refrigerant material.

Chillers may aggregate distribution flow elements forming a refrigeration cycle (compressor, condenser, valve, evaporator), as well as control elements.

Receives electrical power.

Control unit accessing internal sensors and actuators.

Chilled water return.

Chilled water supply.

Incoming cooler air.

Outgoing hotter air.

Receives electrical power.

Control unit accessing internal sensors and actuators.

Chilled water return.

Chilled water supply.

Incoming cooler condenser water.

Outgoing hotter condenser water.

The IfcChimney, as any subtype of IfcBuildingElement, may participate alternatively in one of the two different containment relationships:

• the Spatial Containment (defined here), or
• the Element Composition.

Default spatial container (in most cases the storey where the base of the chimney is placed)

Spatial container for the element if it cannot be assigned to a building storey

Spatial container for the element in case that it is placed on site (outside of building)

Material from which the casing is constructed.

Refrigerant entering the coil.

Refrigerant leaving the coil.

Air entering the surface of the coil.

Air leaving the surface of the coil.

Chilled water entering the coil.

Chilled water leaving the coil.

Air entering the surface of the coil.

Air leaving the surface of the coil.

Heated water entering the coil.

Heated water leaving the coil.

Air entering the surface of the coil.

Air leaving the surface of the coil.

The material of the IfcColumn is defined by the IfcMaterialProfileSet or as fallback by IfcMaterial, and it is attached either directly or at the IfcColumnType.

NOTE  It is illegal to assign an IfcMaterialProfileSetUsage to an IfcColumn. Only the subtype IfcColumnStandardCase supports this concept.

The IfcColumn, as any subtype of IfcBuildingElement, may participate alternatively in one of the two different containment relationships:

• the Spatial Containment (defined here), or
• the Element Composition.

Default spatial container

Spatial container for the element if it cannot be assigned to a building storey

Spatial container for the element in case that it is placed on site (outside of building)

The axis representation can be used to represent the system length of a column that may extent the body length of the column.

NOTE  The 'Axis' is not used to locate the material profile set, only the subtype IfcColumnStandardCase provides this capability.

Three-dimensional reference curve for the column.

The following additional constraints apply to the 'SweptSolid' representation:

• Solid: IfcExtrudedAreaSolid, IfcRevolvedAreaSolid shall be supported
• Profile: all subtypes of IfcProfileDef (with exception of IfcArbitraryOpenProfileDef)
• Extrusion: All extrusion directions shall be supported

Figure 1 illustrates a 'SweptSolid' geometric representation. There are no restrictions or conventions on how to use the local placement (black), solid of extrusion placement (red) and profile placement (green).

Figure 1 — Column swept solid

Figure 2 illustrates use of a special profile type (here IfcIShapeProfileDef) for the definition of the IfcExtrudedAreaSolid.

Figure 2 — Column extrusion of I-Shape

The following additional constraints apply to the 'AdvancedSweptSolid' representation type:

• Solid: IfcSurfaceCurveSweptAreaSolid, IfcFixedReferenceSweptAreaSolid, IfcExtrudedAreaSolidTapered, IfcRevolvedAreaSolidTapered shall be supported.

NOTE  View definitions and implementer agreements can further constrain the allowed swept solid types.

• Profile: see 'SweptSolid' geometric representation
• Extrusion: not applicable

The following constraints apply to the 'Clipping' representation:

• Solid: see 'SweptSolid' geometric representation
• Profile: see 'SweptSolid' geometric representation
• Extrusion: see 'SweptSolid' geometric representation
• Boolean result: The IfcBooleanClippingResult shall be supported, allowing for Boolean differences between the swept solid (here IfcExtrudedAreaSolid) and one or several IfcHalfSpaceSolid.

Figure 1 illustrates a 'Clipping' geometric representation with use of IfcBooleanClippingResult between an IfcExtrudedAreaSolid and an IfcHalfSpaceSolid to create a clipped body.

Figure 1 — Column clipping

An idealized structural member corresponding to the column.

A task for operating on the column.

The IfcColumnStandardCase defines in addition that the IfcColumnType should have a unique IfcMaterialProfileSet, that is referenced by the IfcMaterialProfileSetUsage assigned to all occurrences of this IfcColumnType. Composite profile columns can be represented by refering to several IfcMaterialProfile's within the IfcMaterialProfileSet that is referenced from the IfcMaterialProfileSetUsage.

Figure 1 illustrates assignment of IfcMaterialProfileSetUsage and IfcMaterialProfileSet to the IfcColumnStandardCase as the column occurrence and to the IfcColumnType. The same IfcMaterialProfileSet shall be shared by many occurrences of IfcMaterialProfileSetUsage. This relationship shall be consistent to the relationship between the IfcColumnType and the IfcColumnStandardCase.

Figure 1 — Column profile usage

Figure 2 illustrates cardinal point alignment.

NOTE  It has to be guaranteed that the use of IfcCardinalPointEnum is consistent to the placement of the extrusion body provided by IfcExtrudedAreaSolid.Position

NOTE  The cardinal points 7 (top left), and 6 (mid-depth right) are assigned according to the definition at IfcCardinalPointReference

Figure 2 — Column cardinal points

Figure 3 illustrates assignment of a composite profile by using IfcCompositeProfile for geometric representation and several IfcMaterialProfile's within the IfcMaterialProfileSet. The number of IfcMaterialProfile's within the IfcMaterialProfileSet is restricted to maximal 2 and requires the use of IfcExtrudedAreaSolidTapered, or IfcRevolvedAreaSolidTapered for the correct 'Body' shape representation.

Figure 3 — Column composite profiles

The following restriction is imposed:

• The local placement shall provide the location and directions for the standard column, the x/y plane is the plane for the start profile, and the z-axis is the extrusion axis for the column body (in case of rotation, the tangent direction).

The following additional constraints apply to the 'Axis' representation, if the 'Body' shape representation has the RepresentationType : 'SweptSolid':

• Axis
  • IfcPolyline having two Points, or IfcTrimmedCurve with BasisCurve of Type IfcLine for 'SweptSolid' provided as IfcExtrudedAreaSolid. The axis curve lies on the z axis of the object coordinate system.
  • IfcTrimmedCurve with BasisCurve of Type IfcCircle for 'SweptSolid' provided as IfcRevolvedAreaSolid. The axis curve lies on the x/z plane of the object coordinate system, the tangent at the start is along the positive z-axis.

	EXAMPLE  As shown in Figure 1, the axis shall be defined along the z axis of the object coordinate system. The axis representation can be used to represent the system length of a column that may extent the body length of the column.
Figure 1 — Column axis representation

EXAMPLE  As shown in Figure 2, the axis representation shall be used to represent the cardinal point as the offset between the 'Axis' and the extrusion path of the column. The extrusion path is provided as IfcExtrudedAreaSolid.ExtrudedDirection and should be parallel to the 'Axis'. It has to be guaranteed that the value provided by IfcMaterialProfileSetUsage.CardinalPoint is consistent to the IfcExtrudedAreaSolid.Position.

Figure 2 — Column axis cardinal point

The following additional constraints apply to the 'SweptSolid' representation:

• Solid: IfcExtrudedAreaSolid, IfcRevolvedAreaSolid shall be supported
• Profile: all subtypes of IfcProfileDef (with exception of IfcArbitraryOpenProfileDef)
• Profile Position : For all single profiles, the IfcParameterizedProfileDef.Position shall be NIL, or having Location = 0.,0. and RefDirection = 1.,0.
• Extrusion: perpendicular to the profile direction. The IfcExtrudedAreaSolid.ExtrudedDirection shall be [0.,0.,1.].
• Orientation: The y-axis of the profile, as determined by IfcSweptAreaSolid.Position.P[2] shall point to the Y-Axis. It indicates the "role" of the column, a role=0° means y-axis of profile = Y-axis of reference coordinate system.

Figure 1 illustrates a standard geometric representation with cardinal point applied as 5 (mid-depth centre).

The following interpretation of dimension parameter applies for rectangular columns:

• IfcRectangleProfileDef.YDim interpreted as column width
• IfcRectangleProfileDef.XDim interpreted as column depth

The following interpretation of dimension parameter applies for circular columns:

• IfcCircleProfileDef.Radius interpreted as column radius.

Figure 1 — Column body extrusion

The following additional constraints apply to the 'AdvancedSweptSolid' representation type:

• Solid: IfcSurfaceCurveSweptAreaSolid, IfcFixedReferenceSweptAreaSolid, IfcExtrudedAreaSolidTapered, IfcRevolvedAreaSolidTapered shall be supported.

NOTE  View definitions and implementer agreement can further constrain the allowed swept solid types.

• Profile: see 'SweptSolid' geometric representation
• Profile Position : see 'SweptSolid' geometric representation
• Extrusion: not applicable

The following constraints apply to the 'Clipping' representation:

• Solid: see 'SweptSolid' geometric representation
• Profile: see 'SweptSolid' geometric representation
• Profile Position : see 'SweptSolid' geometric representation
• Extrusion: see 'SweptSolid' geometric representation
• Orientation: see 'SweptSolid' geometric representation
• Boolean result: The IfcBooleanClippingResult shall be supported, allowing for Boolean differences between the swept solid (here IfcExtrudedAreaSolid) and one or several IfcHalfSpaceSolid (or its subtypes).

Figure 1 illustrates a 'Clipping' geometric representation with use of IfcBooleanClippingResult between an IfcExtrudedAreaSolid and an IfcHalfSpaceSolid to create a clipped body, with cardinal point applied as 2 (bottom centre).

Figure 1 — Column body clipping

The material of the IfcColumnType is defined by the IfcMaterialProfileSet or as fall back by IfcMaterial and attached by the IfcRelAssociatesMaterial.RelatingMaterial. It is accessible by the inverse HasAssociations relationship.

NOTE  It is illegal to assign an IfcMaterial to an IfcColumnType, if there is at least one occurrences of IfcColumnStandardCase for this type.

The shared profile definition is defined by assigning an IfcMaterialProfileSet (see material use definition above). The IfcMaterialProfile refers to the subtype of IfcProfileDef that is the common profile for all column occurrence, if used. It is only applicable if the IfcColumnType has only occurrences of type IfcColumnStandardCase (see definition of IfcColumnStandardCase for further information).

NOTE  The attribute ProfileName of the IfcProfileDef subtype, referenced in IfcMaterialProfile should contain a standardized profile name according to local standards. However, an additional geometric representation of the profile is necessary (e.g. as IfcExtrudedAreaSolid). An importing application is allowed to check for the existence of the profile name: in case of identifying it as a standardized name, the corresponding profile geometry and possibly other cross sectional properties can be read from a library. Otherwise the geometric representation and possible non geometric IfcProfileProperties have to be used.

The IfcColumnType may define the shared geometric representation for all column occurrences. The RepresentationMaps attribute refers to a list of IfcRepresentationMap's, that allow for multiple geometric representations (e.g. with IfcShapeRepresentation's having an RepresentationIdentifier 'Box', 'Axis', or 'Body'). It is only applicable if the IfcColumnType has only occurrences of type IfcColumn (See geometric use definition of IfcColumn for further information).

NOTE  If the IfcColumnType has an associated IfcMaterialProfileSet, then no shared geometric representation shall be provided.

NOTE  The product shape representations are defined as RepresentationMaps (attribute of the supertype IfcTypeProduct), which get assigned by an element occurrence instance through the IfcShapeRepresentation.Item[n] being an IfcMappedItem. See IfcTypeProduct for further information.

NOTE  The values of attributes RepresentationIdentifier and RepresentationType of IfcShapeRepresentation are restricted in the same way as those for IfcColumn and IfcColumnStandardCase

Material from which the casing is constructed.

Computers may be aggregated into audio-visual components such as displays, cameras, speakers, or microphones.

Receives electrical power.

Electromagnetic waves.

The modulated analog signal in a circuit, such as a cable connected to a modem.

Receives electrical power.

A network connection, may be wired or wireless (implicit antenna), such as a cable connected from a data outlet jack or from a router communications appliance. While communication is bidirectional, the router-end is considered to be the source.

A device connection such as USB or serial, which may connect to equipment such as a building automation controller.

Audio/video output, such as a cable connected to a display, which may be aggregated into separate channels.

Receives electrical power.

Telephone connection.

Receives electrical power.

Modulated analog signal, typically a cable connecting from a communications junction box or an antenna.

Internet data network.

Television modulated signal.

Telephone communications.

Receives electrical power.

A network connection, may be wired or wireless.

Telephone connection for fax support.

Receives electrical power.

The receiving signal.

The transmitted amplified signal.

Receives electrical power.

Uplink from another network, such as a cable connected to another router or modem accessing the Internet.

A wireless access point.

A network link to a routed device such as a cable connecting to a computer.

A network link to a routed device such as a cable connecting to a computer.

A network link to a routed device such as a cable connecting to a computer.

A network link to a routed device such as a cable connecting to a computer.

A network link to a routed device such as a cable connecting to a computer.

A network link to a routed device such as a cable connecting to a computer.

A network link to a routed device such as a cable connecting to a computer.

A network link to a routed device such as a cable connecting to a computer.

Material from which the casing is constructed.

Refrigerant material.

Uncompressed vapor refrigerant entering the compressor.

Compressed vapor refrigerant leaving the compressor.

Material from which the casing is constructed.

Refrigerant material.

Vapor refrigerant entering the condenser.

Liquid refrigerant leaving the condenser.

Cooler air entering the condenser.

Warmer air leaving the condenser.

Vapor refrigerant entering the condenser.

Liquid refrigerant leaving the condenser.

Makeup water entering the condenser.

Purged water leaving the condenser.

Air entering the condenser.

Air leaving the condenser.

Vapor refrigerant entering the condenser.

Liquid refrigerant leaving the condenser.

Cooler water entering the condenser, optionally from cooling tower.

Warmer water leaving the condenser, optionally to cooling tower.

Indicates a physical element manifesting the resource such as a crane.

The amount incurred for acquiring the equipment, such as rental fees or depreciation.

The amount incurred for operating the equipment, such as fuel and maintenance.

The amount incurred for mobilizing and decomissioning the equipment.

The unit basis for operating the equipment, such as an hour.

Indicates a physical element manifesting the resource such as a pile of sand.

The amount incurred per unit volume of the material.

The unit volume of material used, such as cubic meters of concrete.

Indicates a physical element manifesting the resource such as nails (in bulk).

The unit cost for purchasing the product.

The unit cost for transporting the product.

The unit count of the product used such as 1 for each or 12 for a dozen.

Documents may be published for work plans consisting of schedules, calendars, tasks, and resources. The relationship IfcRelAssociatesDocument may be used to preserve mappings to such document where RelatingDocument points to an IfcDocumentReference and RelatedObjects includes the IfcConstructionResource as shown in Figure 184. IfcDocumentReference.ItemReference identifies the resource within the scope of the document, such as an integer or guid. The IfcDocumentReference.ReferencedDocument corresponds to the document which is uniquely identified by IfcDocumentInformation.DocumentId and/or IfcDocumentInformation.PublicationLocation. Such document mapping allows items in the document to be updated from the building information model and vice-versa.

Figure 1 — Construction resource document use

Constraints may be applied to a resource to indicate fixed work (such as total person-hours) or fixed usage (such as simultaneous workers).

Indicate fixed usage (such as simultaneous workers) such that changes to ScheduleWork should impact the assigned IfcTask.TaskTime.ScheduleDuration and vice-versa.

Indicate fixed work (such as total person-hours) such that changes to ScheduleUsage should impact the assigned IfcTask.TaskTime.ScheduleDuration and vice-versa.

The resource type may provide shared productivity and cost information, allowing tasks and resources to be selected according to lowest cost and/or shortest duration. Given an IfcProduct of a particular IfcTypeProduct type, an IfcTypeProcess may be selected from those assigned to the product type using IfcRelAssignsToProduct, and an IfcTypeResource may be selected from those assigned to the process type using IfcRelAssignsToProcess. Then IfcTask and IfcConstructionResource occurrences may be instantiated from the type definitions, applying productivitity and rate information to assigned quantities to calculate ResourceTime.ScheduleWork. Task durations can then be calculated by dividing ResourceTime.ScheduleWork by ResourceTime.ScheduleUsage.

Figure 1 — Construction resource type use

For time series properties as shown in Figure 180, each IfcTimeSeriesValue indicates a LIST of values, where the sequence of the value corresponds to the IfcCostValue at IfcConstructionResource.CostRatesConsumed. For example, if CostRatesConsumed has two IfcCostValue items in the LIST, "Standard" and "Overtime", then IfcTimeSeriesValue(IfcDuration('T8H0M0S'),IfcDuration('T2H0M0S')) would indicate 8 hours at Standard rate and 2 hours at Overtime rate. If the list of values at IfcTimeSeriesValue.ListValues is less than the size of CostRatesConsumed, then subsequent values are considered to be zero.

Figure 1 — Construction resource time series use

Resources may be decomposed into allocation pools using the IfcRelNests relationship as shown in Figure 181. For example, an IfcLaborResource for "Electrician" may be decomposed into three task-specific IfcLaborResource objects: "Electrical Rough-in", "First Floor Circuits", and "Second Floor Circuits". Both relating and related sides may represent the same ResourceTime.ScheduleUsage quantity (for example, 6 workers time-shared), or the related side may break out ResourceTime.ScheduleUsage quantities for reserved use (for example, 4 workers and 2 workers).

A common scenario is two nesting levels where the first-level resources have no task assignments; while second-level resources have specific task assignments indicating that the resource is subdivided into allocations for specific tasks. While the model allows unlimited nesting of resources, implementer agreements may restrict to two nesting levels with task assignments specifically at the second level.

Figure 1 — Construction resource composition use

Controls have assignments from products, processes, or other objects by using the relationship object IfcRelAssignsToControl.

Figure 1 illustrates controller composition use.

Figure 1 — Controller composition use

May contain IfcController components. Programmable Logic Controllers may be decomposed into logical elements for values and operations.

Material from which the casing is constructed.

Receives the first parameter.

Receives the second parameter (if applicable).

Sets the output value.

Receives the first parameter.

Receives the second parameter (if applicable).

Sets the output value.

Receives electrical power.

Direct communication to the device (e.g. serial port).

Network communication to the device (e.g. TCP/IP network).

Analog or digital inputs.

Analog or digital outputs.

Receives the first parameter.

Receives the second parameter (if applicable).

Sets the output value.

Receives the first parameter.

Receives the second parameter (if applicable).

Sets the output value.

Material from which the casing is constructed.

Chilled water entering.

Chilled water leaving.

Material from which the casing is constructed.

Fill material.

May contain fan components for forcing air into the cooling tower.

May contain fan components for inducing air into the cooling tower.

Warmer water entering the cooling tower.

Cooler water leaving the cooling tower.

Instances of IfcCostItem are used for cost estimates, budgets, and other forms, where a variety of identification codes are used extensively to identify the meaning of the cost. Examples include project phase codes, CSI codes, takeoff sequence numbers, and cost accounts. The model allows for all classes that are ultimately subtypes of IfcObject to inherit the ability to have one or more instances of IfcClassificationReference to be assigned. Where identification codes are required, the generic IfcRelAssociatesClassification facility should be used.

An IfcCostItem can nest other instances of IfcCostItem through its relationships to IfcRelNests. This can be used to enable the development of complex groups of costs as may be found in cost schedules through to pages, sections and complete cost schedules.

There is always a summary cost item as the root item of the tree representing the cost item nesting. Subsequent instances of IfcCostItem are assigned to the summary cost item using IfcRelNests. The summary cost item itself is assigned to IfcCostSchedule through the IfcRelAssignsToControl relationship.

Figure 1 illustrates a cost item composition used for a cost schedule. Each line item has a quantity and separate unit costs where IfcCostValue.CostType indicates the category of cost. The summary item has a hierarchy of costs calculated according to IfcAppliedValueRelationship.ArithmeticOperator, where IfcCostValue.CostType identifies the category to be totalled. The Tax component has IfcCostValue.CostType set to 'Material' which indicates it is the sum of all nested values of the 'Material' category ($3 x 3000 + $118 x 100 = $20800). The Subtotal component has IfcCostValue.CostType set to an asterisk ('*') which indicates it is the sum of all nested values of all categories.

Figure 1 — Cost composition

An IfcCostItem can be calculated based on quantities from objects through its relationship to IfcRelAssignsToControl.

For quantity-based costing, IfcElement, IfcTask, or IfcResource occurrence subtypes may be used. Multiple elements may be assigned of the same or different types, using IfcPhysicalQuantity entities defined at each object. Each IfcPhysicalQuantity type must be identical (for example, all values are IfcAreaQuantity) such that they can be added together.

For rate-based costing (specifically for IfcCostScheduleTypeEnum.SCHEDULEOFRATES), a single IfcTypeProduct, IfcTypeProcess, or IfcTypeResource subtype may be used to reflect rates for occurrences of such types. This enables the possibility to generate a quantity-based cost schedule for occurrences based on types with rate-based cost schedules.

IfcRelAssignsToControl is also used in the opposite direction to link the root IfcCostItem to an IfcCostSchedule where RelatingControl is the IfcCostSchedule.

Figure 1 illustrates cost item assignment derived from building elements. The IfcRelAssignsToControl relationship indicates building elements for which quantities are derived. Not shown, costs may also be derived from building elements by traversing assignment relationships from the assigned IfcProduct to IfcProcess to IfcResource, where all costs ultimately originate at resources. It is also possible for cost items to have assignments from processes or resources directly.

Figure 1 — Cost assignment

For quantity-based costs based on product occurrences, spatial structures, or other physical artifacts.

For quantity-based costs based on tasks, procedures, or events.

For quantity-based costs based on resource allocations.

For cost rates based on product models.

For cost rates based on process models of historical or projected duration.

For cost rates based on resource models of historical or projected productivity.

Approvals may be associated to indicate the status of acceptance or rejection using the IfcRelAssociatesApproval relationship where RelatingApproval refers to an IfcApproval and RelatedObjects contains the IfcCostSchedule. Approvals may be split into sub-approvals using IfcApprovalRelationship to track approval status separately for each party where RelatingApproval refers to the higher-level approval and RelatedApprovals contains one or more lower-level approvals. The hierarchy of approvals implies sequencing such that a higher-level approval is not executed until all of its lower-level approvals have been accepted.

The IfcCostSchedule may be assigned to the following entities using relationships as indicated:

• IfcActor (IfcRelAssignsToActor): Persons and organizations involved in the preparation, submittal, and as target users.

The IfcCostSchedule may have assignments of its own using the IfcRelAssignsToControl relationship where RelatingControl refers to the IfcCostSchedule and RelatedObjects contains one or more objects of the following types:

• IfcCostItem: Indicates costs published within this cost schedule, typically a single root cost item forming a hierarchy of nested cost items.

The IfcCovering has a containment relationship within the hierarchical spatial structure.

• The IfcCovering is places within the project spatial hierarchy using the objectified relationship IfcRelContainedInSpatialStructure, referring to it by its inverse attribute SELF\IfcElement.ContainedInStructure. Subtypes of IfcSpatialStructureElement are valid spatial containers, with IfcSpace being the default container.

Coverings for surfaces (CEILING, FLOORING, CLADDING, CEILING, ROOFING) may have materials defined according to layers.

Optional front-facing material of layer-based coverings such as drywall paper.

The solid material of layer-based coverings such as drywall gypsum.

Optional back-facing material of layer-based coverings such as drywall paper.

Coverings for edges (MOLDING, SKIRTINGBOARD) may have materials defined according to profiles.

Profile of trim such as crown molding or base molding.

The following additional constraints apply to the 'GeometricSet' representation of IfcCovering:

• for planar base surfaces - bounded surface representation
• for cylindrical base surfaces - swept surface representation

	EXAMPLE  Figure 1 illustrates a planar surface representation where the area of IfcCovering is given by an IfcPolyLoop for planar base surfaces (here provided by the IfcRelSpaceBoundary). The implicit planar surface of the IfcPolyLoop shall be identical with the planar surface defined by the IfcRelSpaceBoundary.
Figure 1 — Covering surface planar

EXAMPLE  Figure 2 illustrates a cylindrical surface representation where the area of the IfcCovering is given by an IfcSurfaceOfLinearExtrusion for cylindrical base surfaces (here given by the IfcRelSpaceBoundary, such as caused by a round wall). The geometry representation of the IfcCovering is given by the IfcTrimmedCurved (the Curve parameter of the IfcArbitraryOpenProfileDef - in cases of faceted representation also an IfcPolyline). It is extruded within the plane of the base surface using the Depth parameter of the IfcSurfaceOfLinearExtrusion.

Figure 2 — Covering surface cylindrical

The following additional constraints apply to the 'SweptSolid' representation of IfcCovering:

• for planar base surfaces - swept area representation
• for cylindrical base surfaces - swept area representation

	EXAMPLE  Figure 1 illustrates a body representation where the volume of IfcCovering is given by an IfcExtrudedAreaSolid for planar base surfaces (here given by the IfcRelSpaceBoundary). The extruded area (IfcArbitraryClosedProfileDef) shall be coplanar to the surface defined by the IfcRelSpaceBoundary.
Figure 1 — Covering body planar

EXAMPLE  Figure 2 illustrates a body representation where the volume of the IfcCovering is given by an IfcExtrudedAreaSolid for cylindrical base surfaces (here given by the IfcRelSpaceBoundary - such as caused by a round wall). The geometry representation of the IfcCovering is given by the IfcCompositeCurve (the OuterCurve parameter of the IfcArbitraryClosedProfileDef - in cases of faceted representation also a closed IfcPolyline). It is extruded along the plane of the base surface using the Depth parameter of the IfcSurfaceOfLinearExtrusion.

Figure 2 — Covering body circular

The material of the IfcCoveringType is defined by IfcMaterialLayerSet for layer-based coverings or as fall back by IfcMaterial and attached by the IfcRelAssociatesMaterial.RelatingMaterial. It is accessible by the inverse HasAssociations relationship.

The material of the IfcCoveringType is defined by IfcMaterialProfileSet for profile-based coverings or as fall back by IfcMaterial and attached by the IfcRelAssociatesMaterial.RelatingMaterial. It is accessible by the inverse HasAssociations relationship.

The IfcCoveringType may define the shared geometric representation for all covering occurrences. The RepresentationMaps attribute refers to a list of IfcRepresentationMap's, that allow for multiple geometric representations (e.g. with IfcShaperepresentation's having an RepresentationIdentifier 'Box', 'Surface', or 'Body'). (See geometric use definition of IfcCovering for further information).

NOTE  If the IfcCoveringType has an associated IfcMaterialLayerSet, then no shared geometric representation shall be provided.

NOTE  The product shape representations are defined as RepresentationMaps (attribute of the supertype IfcTypeProduct), which get assigned by an element occurrence instance through the IfcShapeRepresentation.Item[n] being an IfcMappedItem. See IfcTypeProduct for further information.

NOTE  The values of attributes RepresentationIdentifier and RepresentationType of IfcShapeRepresentation are restricted in the same way as those for IfcCoveringType.

Default spatial container

Spatial container for the element if it cannot be assigned to a building storey - curtain wall facades may be assigned directly to the building

Spatial container for the element in case that it is placed on site (outside of building)

The following restriction may be imposed by view definitions or implementer agreements:

• If the IfcCurtainWall establishes an aggregate, then all contained elements shall be placed relative to the IfcCurtainWall.ObjectPlacement.

The following additional constraints apply to the 'Axis' representation:

• Geometry : IfcPolyline having two Points, or IfcTrimmedCurve with BasisCurve of type IfcLine or IfcCircle.

The material from which the damper blades are constructed.

The material from which the damper frame is constructed.

The material from which the damper seals are constructed.

Air entering damper.

Air leaving damper, with flow regulated according to position of damper.

The material of the IfcDistributionChamberElement is defined by IfcMaterialConstituentSet or as a fallback by IfcMaterial, and attached by the RelatingMaterial attribute on the IfcRelAssociatesMaterial relationship. It is accessible by the HasAssociations inverse attribute. Material information can also be given at the IfcDistributionChamberElementType, defining the common attribute data for all occurrences of the same type. The following keywords for IfcMaterialConstituentSet.MaterialConstituents[n].Name shall be used:

• 'Base': The material from which the base of the duct is constructed.
• 'Cover': The material from which the access cover to the chamber is constructed.
• 'Fill': The material that is used to fill the duct (where used).
• 'Wall': The material from which the wall of the duct is constructed.

The material from which the base of the duct is constructed.

The material from which the access cover to the chamber is constructed.

The material that is used to fill the duct (where used).

The material from which the wall of the duct is constructed.

In addition to general product and project classification (UniFormat, etc.), classifications may also be applied to indicate a device address or addressing scheme according to system-based device instance classification.

Figure 1 illustrates classification usage.

Figure 1 — Distribution control classification

32-bit decimal BACnetObjectIdentifier indicating type ID and instance ID (e.g.'12.15' for Digital Input #15).

32-bit decimal address for an IPv4 network (e.g.'192.168.1.1').

128-bit hexadecimal address for an IPv6 network.

48-bit hexadecimal form of MAC address.

Hierarchical ItemID in alphanumeric form (i.e. 'B204.Tank2.Temperature)

24-bit hexadecimal instance address.

48-bit hexadecimal neuron ID.

The IfcDistributionControlElement may be assigned to the following entities using relationships as indicated:

• IfcDistributionSystem (IfcRelAssignsToGroup): Indicates a system containing interconnected devices, where control elements are typically part of a control system having PredefinedType=CONTROL.
• IfcPerformanceHistory (IfcRelAssignsToControl): Indicates realtime or historical infomation captured for the device.

Indicates tasks used to purchase, install, renovate, demolish, operate, or otherwise act upon the element. If the element has a type, available task types are assigned to the element type.

Indicates procedures used to operate the element. If the element has a type, available procedure types are assigned to the element type.

Indicates events to be handled by the element, sequenced by procedures to be followed. If the element has a type, available event types are assigned to the element type.

Indicates task types available to purchase, install, renovate, demolish, operate, or otherwise act upon occurrences of the element type. Such task types may be instantiated as task occurrences assigned to occurrences of the element type. Prices (such as for purchasing or shipping) may be established by resource types assigned to task types.

Indicates procedure types available to operate occurrences of the element type. Such procedure types may be instantiated as procedure occurrences assigned to occurrences of the element type.

Indicates event types available to be raised by occurrences of the element type, sequenced by procedures to be followed. Such event types may be instantiated as event occurrences assigned to occurrences of the element type.

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 this specification.

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.

The IfcDistributionElement may be contained within the spatial containment tree. The IfcSpace is the default spatial container.

NOTE  The 'Spatial Containment' concept is mandatory in many model view definitions.

The container for distribution elements spanning through two or more spaces.

The default container for distribution elements,

This represents the 3D flow path of the item having IfcShapeRepresentation.RepresentationType of 'Curve3D' and containing a single IfcBoundedCurve subtype such as IfcPolyline, IfcTrimmedCurve, or IfcCompositeCurve. For elements containing directional ports (IfcDistributionPort with FlowDirection of SOURCE or SINK), the direction of the curve indicates direction of flow where a SINK port is positioned at the start of the curve and a SOURCE port is positioned at the end of the curve. This representation is most applicable to flow segments (pipes, ducts, cables), however may be used at other elements to define a primary flow path if applicable.

This represents the 3D clearance volume of the item having RepresentationType of 'Surface3D'. Such clearance region indicates space that should not intersect with the 'Body' representation of other elements, though may intersect with the 'Clearance' representation of other elements. The particular use of clearance space may be for safety, maintenance, or other purposes.

This represents the 3D flow path of the item having IfcShapeRepresentation.RepresentationType of 'Curve3D' and containing a single IfcBoundedCurve subtype such as IfcPolyline, IfcTrimmedCurve, or IfcCompositeCurve. For elements containing directional ports (IfcDistributionPort with FlowDirection of SOURCE or SINK), the direction of the curve indicates direction of flow where a SINK port is positioned at the start of the curve and a SOURCE port is positioned at the end of the curve. This representation is most applicable to flow segment types (pipes, ducts, cables), however may be used at other elements to define a primary flow path if applicable.

If an element type is defined parametrically (such as a flow segment type defining common material profile but no particular length or path), then no representations shall be asserted at the type.

NOTE  The product representations are defined as representation maps (at the level of the supertype IfcTypeProduct, which get assigned by an element occurrence instance through the IfcShapeRepresentation.Item[1] being an IfcMappedItem.

This represents the 3D clearance volume of the item having RepresentationType of 'Surface3D'. Such clearance region indicates space that should not intersect with the 'Body' representation between element occurrences, though may intersect with the 'Clearance' representation of other element occurrences. The particular use of clearance space may be for safety, maintenance, or other purposes.

This represents the light emission of the item having IfcShapeRepresentation.RepresentationType of 'LightSource' and containing one or more IfcLightSource subtypes. This representation is most applicable to lamps and light fixtures, however may be used at other elements that emit light.

The placement of a port indicates the position and orientation of how it may connect to a compatible port on another product. The placement shall be relative to the nesting IfcDistributionElement, IfcDistributionElementType, or enclosing IfcDistributionPort.

The Location is the midpoint of the physical connection, unless otherwise indicated by cardinal point on a material profile.

The Axis points in the direction of the physical connection away from the product if FlowDirection equals SOURCE (or SOURCEANDSINK or NOTDEFINED), or points opposite direction (to the product) if the FlowDirection equals SINK.

NOTE  The rationale for positioning the Axis in the direction of flow is to allow for the same geometry to be used, such as for connectors with polarized cross-section.

The RefDirection points in the direction of the local X axis of the material profile, where the local Y axis points up if looking towards the Axis where the local X axis points right.

Upon connecting elements through ports with rigid connections, each object shall be aligned such that the effective Location, Axis, and RefDirection of each port is aligned to be equal (with exception for circular profiles where the RefDirection need not be equal).

Distribution ports are indicated on products and product types using the IfcRelNests relationship where RelatingObject refers to the enclosing IfcDistributionElement or IfcDistributionElementType respectively. The order of ports indicates logical ordering such within outlets, junction boxes, or communications equipment.

Ports may be further nested into sub-ports, for indicating specific connections on components or pins.

IfcDistributionPort may be connected to other objects as follows using the indicated relationship:

• IfcDistributionPort (IfcRelConnectsPorts) : Indicates a connection to another port having the same type and opposite flow direction. For port connections between elements, the RelatingPort is set to a port having FlowDirection=SOURCE and the RelatedPort is set to a port having FlowDirection=SINK. For aggregation scenarios, ports on a device may be mapped to aggregated devices within, in which case ports on the outer device indicate a single FlowDirection but have an additional connection internally to a port on an aggregated inner device. Refer to IfcUnitaryEquipment for an example.
• IfcDistributionElement (through IfcRelConnectsPortToElement): For dynamic ports, indicates the containing element.

Figure 1 illustrates distribution port connectivity.

Figure 1 — Distribution port connectivity

The IfcDistributionPort may be assigned to the following entities using relationships as indicated:

• IfcDistributionSystem (through IfcRelAssignsToGroup): Indicates a system containing interconnected devices.
• IfcPerformanceHistory< (through IfcRelAssignsToControl): Indicates real time or historical infomation captured for the device.

Indicates a system that is hosted by the port, as the origination.

Indicates a circuit that is switched by the port, as the origination.

Indicates electrical subsystems within the system.

Indicates electrical circuits within the system.

For the most common case of an IfcDistributionElement subtype containing ports of a particular PredefinedType that all belong to the same distribution system, the IfcDistributionElement is assigned to the IfcDistributionSystem via the IfcRelAssignsToGroup relationship, where IfcDistributionPort's are implied as part of the corresponding system based on their PredefinedType. An IfcDistributionElement may belong to multiple systems, however only one IfcDistributionSystem of a particular PredefinedType.

For rare cases where an IfcDistributionElement subtype contains ports of the same PredefinedType yet different ports belong to different systems, alternatively each IfcDistributionPort may be directly assigned to a single IfcDistributionSystem via the IfcRelAssignsToGroup relationship, where the PredefinedType must match. Such assignment indicates that the IfcDistributionSystem assigned from the IfcDistributionPort overrides any such system of the same PredefinedType assigned from the containing IfcDistributionElement, if any.

Additionally, an IfcDistributionSystem may in turn be assigned to an IfcDistributionPort indicating the host or origination of the system using IfcRelAssignsToProduct.

EXAMPLE  A gas-powered hot water heater may have three ports: GAS, DOMESTICCOLDWATER, and DOMESTICHOTWATER. The heater is a member of two systems (GAS and DOMESTICCOLDWATER), and hosts one system (DOMESTICHOTWATER) at the corresponding port.

Figure 1 illustrates a distribution system for an electrical circuit.

Figure 1 — Distribution system assignment

Indicates devices that are part of the system, where any ports of the same PredefinedType are considered part of the system implicitly.

Indicates port that is explicitly part of the system, which overrides any system assignment of the containing device.

The opening direction is determined by the local placement of IfcDoor and the OperationType of the IfcDoorType as shown in Figure 1.

NOTE  There are different definitions in various countries on what a left opening or left hung or left swing door is (same for right). Therefore the IFC definition may derivate from the local standard and need to be mapped appropriately.

Opening directions Definitions Reference to other standards The door panel (for swinging doors) opens always into the direction of the positive Y axis of the local placement. The determination of whether the door opens to the left or to the right is done at the level of the IfcDoorType. Here it is a left side opening door given by IfcDoorType.OperationType = SingleSwingLeft refered to as LEFT HAND (LH) in US * refered to as DIN-R (right hung) in Germany If the door should open to the other side, then the local placement has to be changed. It is still a left side opening door, given by IfcDoorType.OperationType = SingleSwingLeft refered to as RIGHT HAND REVERSE (RHR) in US * refered to as DIN-R (right hung) in Germany If the door panel (for swinging doors) opens to the right, a separate door style needs to be used (here IfcDoorTypee.OperationType = SingleSwingRight) and it always opens into the direction of the positive Y axis of the local placement. refered to as RIGHT HAND (RH) in US * refered to as DIN-L (left hung) in Germany If the door panel (for swinging doors) opens to the right, and into the opposite directions, the local placement of the door need to change. The door style is given by IfcDoorType.OperationType = SingleSwingRight. refered to as LEFT HAND REVERSE (LHR) in US * refered to as DIN-L (left hung) in Germany * it assumes that the 'inside/private/primary' space is above (top in the pictures) and the 'outside/public/secondary' space is below (bottom in the pictures).

Figure 1 — Door swing

NOTE  The OverallWidth and OverallHeight parameters are for informational purpose only.

NOTE This type is deprecated

The material of the IfcDoor is defined by the IfcMaterialConstituentSet or as fall back by IfcMaterial and attached by the IfcRelAssociatesMaterial relationship.

Indicates that the material constituent applies to the door lining.

Indicates that the material constituent applies to the door panel(s); if not provided, the 'Lining' material information applies to panel(s) as well.

Indicates that the material constituent applies to the glazing part.

The following restriction is imposed:

1. The PlacementRelTo relationship of IfcLocalPlacement shall point to the local placement of the same element (if given), in which the IfcDoor is used as a filling (normally an IfcOpeningElement), as provided by the IfcRelFillsElement relationship;
2. If the IfcDoor is part of an assembly, e.g. an IfcCurtainWall, then the PlacementRelTo relationship of IfcLocalPlacement shall point (if given) to the local placement of that assembly;
3. If the IfcDoor is not inserted into an IfcOpeningElement, then the PlacementRelTo relationship of IfcLocalPlacement shall point (if given) to the local placement of the same IfcSpatialStructureElement that is used in the ContainedInStructure inverse attribute or to a referenced spatial structure element at a higher level.

NOTE  The product placement is used to determine the opening direction of the door.

The door profile is represented by a three-dimensional closed curve within a particular shape representation. The profile is used to apply the parameter of the parametric door representation. Only a single closed curve shall be contained in the set of IfcShapeRepresentation.Items.

A 'Profile' representation has to be provided if a parametric representation is applied to the door.

The IfcDoor, as any subtype of IfcBuildingElement, may participate alternatively in one of the two different containment relationships:

• the Spatial Containment (defined here), or
• the Element Composition.

The IfcDoor may also be connected to the IfcOpeningElement in which it is placed as a filler. In this case, the spatial containment relationship shall be provided, see Figure 1.

	NOTE  The containment shall be defined independently of the filling relationship, that is, even if the IfcDoor is a filling of an opening established by IfcRelFillsElement, it is also contained in the spatial structure by IfcRelContainedInSpatialStructure.
Figure 1 — Door spatial containment

Default spatial container

Spatial container for the element if it cannot be assigned to a building storey

Spatial container for the element in case that it is placed on site (outside of building)

In particular use cases, a door maybe assigned directly to space

The door profile is represented by a three-dimensional closed curve within a particular shape representation. The profile is used to apply the parameter of the parametric door representation. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

• RepresentationIdentifier : 'Profile'
• RepresentationType : 'Curve3D' or 'GeometricCurveSet', in case of 'GeometricCurveSet' only a single closed curve shall be contained in the set of IfcShapeRepresentation.Items.

The following additional constraints apply to the 'Profile' representation type:

• Curve: being an IfcPolyline defining a rectangle.
• Position: The curve shall lie in the xz plane of the object placement coordinate (the y coordinate values of the IfcCartesianPoint's shall be 0.).

EXAMPLE  Figure 1 illustrates applying the door lining parameters to the door profile shape representation. The profile defines the outer boundary to which the door lining parameters relate as: <li class="small"><em>IfcDoorLiningProperties.LiningDepth</em> starting at distance defined by LiningOffset going into the positive y direction. <li class="small"><em>IfcDoorLiningProperties.LiningThickness</em> offset into the inner side of the rectangle. IfcDoorLiningProperties.LiningOffset distance along the positive y direction to where the LiningDepth applies. IfcDoorLiningProperties.ThresholdThickness starting at the bottom edge of the rectangle into the inner side of the rectangle <li class="small"><em>IfcDoorLiningProperties.ThresholdDepth</em> starting at distance defined by LiningOffset going into the positive y direction. <li class="small"><em>IfcDoorLiningProperties.TransomOffset</em> starting at the bottom edge of the rectangle (along local x axis) into the inner side of the rectangle, distance provided as percentage of overall height. Distance to the centre line of the transom.

Figure 1 — Door profile

Two subtypes of IfcPreDefinedPropertySet are applicable to IfcDoorType:

• IfcDoorLiningProperties - a single instance to define the shape parameters of the door lining
• IfcDoorPanelProperties - one or several instances to define the shape parameters of the door panel(s)

Material from which the duct fitting is constructed.

The outer coating, if applicable.

The insulating wrapping, if applicable.

The inner lining, if applicable.

The flow inlet.

The flow outlet.

The flow inlet.

The flow outlet.

The flow outlet.

The flow inlet.

The flow inlet.

The left flow outlet.

The right flow outlet.

The flow inlet.

The flow outlet.

Material from which the duct fitting is constructed.

The outer coating, if applicable.

The insulating wrapping, if applicable.

The inner lining, if applicable.

The flow inlet.

The flow outlet.

Material from which the casing is constructed.

The flow inlet.

The flow outlet.

Material from which the casing is constructed.

Receives electrical power.

Hot water used for washing dishes.

Drainage from used water.

Receives electrical power.

Receives electrical power.

Receives electrical power.

Cold water used for icemaking and/or drinking water.

Receives electrical power.

Receives electrical power.

Receives electrical power.

Receives electrical power.

Gas source if applicable.

Exhaust air.

Receives electrical power.

Cold water used for washing.

Hot water used for washing.

Drainage from used water.

Material from which the casing is constructed.

Incoming power, such as a cable connecting from the electrical utility or another distribution board.

Grounding connection, such as a cable connecting to a cable fitting connected to a cold water pipe segment coming from the ground.

A downstream circuit, typically connected to a circuit breaker protective device.

A downstream circuit, typically connected to a circuit breaker protective device.

A downstream circuit, typically connected to a circuit breaker protective device.

A downstream circuit, typically connected to a circuit breaker protective device.

A downstream circuit, typically connected to a circuit breaker protective device.

A downstream circuit, typically connected to a circuit breaker protective device.

A downstream circuit, typically connected to a circuit breaker protective device.

A downstream circuit, typically connected to a circuit breaker protective device.

Material from which the casing is constructed.

Incoming power used to charge the flow storage device.

Outgoing power backed by the flow storage device.

Material from which the casing is constructed.

Engine-Generator sets may optionally include an engine to indicate specific detail.

Outgoing power from generator.

Material from which the casing is constructed.

Receives electrical power.

Motor connection to a driven device.

Material from which the casing is constructed.

Receives electrical power.

Transmits electrical power according to time.

The object placement for any subtype of IfcElement is defined by the IfcObjectPlacement, either IfcLocalPlacement or IfcGridPlacement, which defines the local object coordinate system that is referenced by all geometric representations of that IfcElement.

Relative placement according to position and rotation relative to container.

Absolute placement according to position and rotation of world coordinate system.

The 'CoG', Center of Gravity, shape representation is used as a means to verify the correct import by comparing the CoG of the imported geometry with the explicily provided CoG created during export.

Any collection of points and curves representing the floor plan projection.

Any collection of points and curves, and additional hatching and text representing the floor plan projection.

Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a mixed representation, including surface and solid models.

Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple surface models, based on either shell or face based surface models. It may also include tessellated models.

	EXAMPLE  As shown in Figure 1, the surface model representation is given by an IfcShapeRepresentation, which includes a single item which is either an IfcShellBasedSurfaceModel, or an IfcFaceBasedSurfaceModel. In some cases it may also be useful to expose a simple representation as a bounding box representation of the same complex shape.
Figure 1 — Element surface model representation

Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple tessellated surface models, in particular triangulated surface models.

Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented as a single or multiple Boundary Representation models (which are restricted to be faceted Brep's with or without voids). The Brep representation allows for the representation of complex element shape.

	EXAMPLE  As shown in Figure 1, the Brep representation is given by an IfcShapeRepresentation, which includes one or more items, all of type IfcFacetedBrep. In some cases it may be useful to also expose a simple representation as a bounding box representation of the same complex shape.
Figure 1 — Building element body boundary representation

An IfcElement (so far no further constraints are defined at the level of its subtypes or by view definitions) may be represented as a single or multiple boundary representation models, which include advanced surfaces, usually refered to as NURBS surfaces. The 'AdvancedBrep' representation allows for the representation of complex free-form element shape.

NOTE  View definitions or implementer agreements may restrict or disallow the use of 'AdvancedBrep' geometry.

Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented a CSG primitive or CSG tree. The CSG representation allows for the representation of complex element shape.

NOTE  View definitions or implementer agreements may restrict or disallow the use of 'CSG' geometry.

Any IfcElement (so far no further constraints are defined at the level of its subtypes) may be represented using the 'MappedRepresentation'. This shall be supported as it allows for reusing the geometry definition of a type at all occurrences of the same type. The results are more compact data sets.

The same constraints, as given for 'SurfaceOrSolidModel', 'SurfaceModel', 'Tessellation', 'Brep', and 'AdvancedBrep' geometric representation, shall apply to the IfcRepresentationMap.

Product placement with a Product Linear Placement template. It defines the local coordinate system based on the curve which is referenced by IfcLinearPlacement.RelativePlacement which is an IfcAxis2PlacementLinear.Location using an IfcPointByDistanceExpression.BasisCurve. The local coordinate system is based on the tangent of the curve at Location, its normal in the global Z plane and the cross product of the aforementioned vectors.

Distance can be measured along any physical element that has a representation featuring an IfcBoundedCurve that can be used as an Axis in IfcLinearPositioningElement.

The IfcElementAssembly shall represent an aggregate, i.e. it should have other elements, being subtypes of IfcElement, as contained (sub)parts. The table above only represents a selection of subtypes of IfcElement that are legitimate as parts in an IfcElementAssembly

• The IfcElementAssembly is an aggregate i.e. being composed by other elements and acting as an assembly using the objectified relationship IfcRelAggregates, refering to it by its inverse attribute SELF\IfcObjectDefinition.IsDecomposedBy. Components of an assembly are described by instances of subtypes of IfcElement.
• In this case, the contained subtypes of IfcElement shall not be additionally contained in the project spatial hierarchy, i.e. the inverse attribute SELF\IfcElement.ContainedInStructure of those IfcElement's shall be NIL.

Figure 1 illustrates spatial containment and element aggregation relationships.

Figure 1 — Element assembly containment

Members within the assembly.

Plates within the assembly.

Components within the assembly.

The IfcElementAssembly should have a relationship for its containment in the hierachical spatial structure of the project. Only if the IfcElementAssembly is itself a part of another assembly this relationship should be omitted.

Default spatial container

Spatial container for element assemblies not assignable to a building storey

Spatial container for element assemblies that are placed on site (outside of building)

The mapped item, IfcMappedItem, should be used if appropriate as it allows for reusing the geometry definition of a type at all occurrences of the same type.

A single instance of a subtype of IfcElementComponent can stand for several actual element components at once. In this case, the IfcShapeRepresentation contains as many mapped items as there are element components combined within this occurrence object.

	EXAMPLE  Figure 1 illustrates multiple components modeled as a single occurrence object (here: IfcFastener)
Figure 1 — Element component mapped representation

Representation identifier and type are the same as in single mapped representation. The number of mapped items in the representation corresponds with the count of element components in the IfcElementQuantity.

Material from which the casing is constructed.

The fuel inlet.

Connection to the driven source.

Material from which the casing is constructed.

Heat exchanger media material.

Incoming water.

Incoming air.

Outgoing air saturated with vapor.

Material from which the casing is constructed.

Refrigerant material.

Liquid refrigerant entering the evaporator.

Liquid refrigerant entering the evaporator.

Air return entering the evaporator.

Air supply leaving the evaporator.

Liquid refrigerant entering the evaporator.

Liquid refrigerant entering the evaporator.

Chilled water return entering the evaporator.

Chilled water supply leaving the evaporator.

Liquid refrigerant entering the evaporator.

Vapor refrigerant leaving the evaporator.

Chilled water return entering the evaporator.

Chilled water supply leaving the evaporator.

The IfcEvent defines the anticipated or actual occurrence of any event; common information about event types is handled by IfcEventType.

IfcEvent may be contained within an IfcTask using the IfcRelNests relationship. The event is considered active during the time period of the enclosing task (including any assigned IfcWorkCalendar); that is such event may be triggered within the task time period but not outside of it. As an IfcEvent is considered to be atomic, no use is anticipated for nesting processes inside the event.