IFC 4.3.2.20250327 (IFC4X3_ADD2) under development

5.4.3.81 IfcVirtualElement

5.4.3.81.1 Semantic definition

A virtual element is a special element used to provide imaginary, placeholder, or provisional areas, volumes, and boundaries. Virtual elements are usually not displayed and do not have quantities, associated materials, and other measures.

Uses of IfcVirtualElement include:

  • An imaginary boundary such as between two adjacent, but not separated, spaces. The IfcVirtualElement may provide the 2D curve or 3D surface representation of the virtual space connection and is referenced by two instances of IfcRelSpaceBoundary, each pointing to one of the two adjacent IfcSpaces. The boundary is exchanged using PredefinedType = BOUNDARY.
  • A provision for voids. Such as where a particular volume of space is requested by an engineering function that might later be accepted or rejected. If accepted it is transformed into a void within a building element, like a wall opening, or a slab opening. The provision for voids is exchanged using the PredefinedType = PROVISIONFORVOID. Typically this shall use a swept solid geometry, where the profile of the swept solid lies on/near the surface of the referred building element and the extrusion depths is equal to or bigger then (in case of round or otherwise irregular element shape) the thickness of the building element. The appropriate property set Pset_ProvisionForVoid should be attached.
  • A clearance space. Typically a placeholder for the necessary space allocation for future designed elements, such as mechanical equipment that will be determined in a later design phase. It is also used for structure gauge. The clearance is exchanged using the PredefinedType = CLEARANCE.

Figure 5.4.3.81.A describes how to use IfcRelSpaceBoundary in conjunction with IfcVirtualElement to define space boundaries.

space boundary
Figure 5.4.3.81.A — Virtual element used as space boundaries

5.4.3.81.2 Entity inheritance

5.4.3.81.3 Attributes

# Attribute Type Description
IfcRoot (4)
IfcObjectDefinition (7)
IfcObject (5)
IfcProduct (5)
IfcElement (13)
Click to show 34 hidden inherited attributes
IfcVirtualElement (1)
9 PredefinedType OPTIONAL IfcVirtualElementTypeEnum

A list of types to further identify the object. Some property sets may be specifically applicable to one of these types.

Table 5.4.3.81.E

5.4.3.81.4 Formal propositions

Name Description
CorrectPredefinedType

Either the PredefinedType attribute is unset, or the inherited attribute ObjectType must be asserted when the value of PredefinedType is set to USERDEFINED.

NOT(EXISTS(PredefinedType)) OR
(PredefinedType <> IfcVirtualElementTypeEnum.USERDEFINED) OR
((PredefinedType = IfcVirtualElementTypeEnum.USERDEFINED) AND EXISTS (SELF\IfcObject.ObjectType))
Table 5.4.3.81.F

5.4.3.81.5 Property sets

  • Pset_Condition
    • AssessmentDate
    • AssessmentCondition
    • AssessmentDescription
    • AssessmentType
    • AssessmentMethod
    • LastAssessmentReport
    • NextAssessmentDate
    • AssessmentFrequency
  • Pset_ConstructionAdministration
    • ProcurementMethod
    • SpecificationSectionNumber
    • SubmittalIdentifer
  • Pset_ConstructionOccurence
    • InstallationDate
    • ModelNumber
    • TagNumber
    • AssetIdentifier
  • Pset_ElementKinematics
    • CyclicPath
    • CyclicRange
    • LinearPath
    • LinearRange
    • MaximumAngularVelocity
    • MaximumConstantSpeed
    • MinimumTime
  • Pset_EnvironmentalCondition
    • ReferenceAirRelativeHumidity
    • ReferenceEnvironmentTemperature
    • MaximumAtmosphericPressure
    • StorageTemperatureRange
    • MaximumWindSpeed
    • OperationalTemperatureRange
    • MaximumRainIntensity
    • SaltMistLevel
    • SeismicResistance
    • SmokeLevel
    • MaximumSolarRadiation
  • Pset_EnvironmentalImpactIndicators
    • Reference
    • FunctionalUnitReference
    • IndicatorsUnit
    • LifeCyclePhase
    • ExpectedServiceLife
    • TotalPrimaryEnergyConsumptionPerUnit
    • WaterConsumptionPerUnit
    • HazardousWastePerUnit
    • NonHazardousWastePerUnit
    • ClimateChangePerUnit
    • AtmosphericAcidificationPerUnit
    • RenewableEnergyConsumptionPerUnit
    • NonRenewableEnergyConsumptionPerUnit
    • ResourceDepletionPerUnit
    • InertWastePerUnit
    • RadioactiveWastePerUnit
    • StratosphericOzoneLayerDestructionPerUnit
    • PhotochemicalOzoneFormationPerUnit
    • EutrophicationPerUnit
  • Pset_EnvironmentalImpactValues
    • TotalPrimaryEnergyConsumption
    • WaterConsumption
    • HazardousWaste
    • NonHazardousWaste
    • ClimateChange
    • AtmosphericAcidification
    • RenewableEnergyConsumption
    • NonRenewableEnergyConsumption
    • ResourceDepletion
    • InertWaste
    • RadioactiveWaste
    • StratosphericOzoneLayerDestruction
    • PhotochemicalOzoneFormation
    • Eutrophication
    • LeadInTime
    • Duration
    • LeadOutTime
  • Pset_InstallationOccurrence
    • InstallationDate
    • AcceptanceDate
    • PutIntoOperationDate
  • Pset_MaintenanceStrategy
    • AssetCriticality
    • AssetFrailty
    • AssetPriority
    • MonitoringType
    • AccidentResponse
  • Pset_MaintenanceTriggerCondition
    • ConditionTargetPerformance
    • ConditionMaintenanceLevel
    • ConditionReplacementLevel
    • ConditionDisposalLevel
  • Pset_MaintenanceTriggerDuration
    • DurationTargetPerformance
    • DurationMaintenanceLevel
    • DurationReplacementLevel
    • DurationDisposalLevel
  • Pset_MaintenanceTriggerPerformance
    • TargetPerformance
    • PerformanceMaintenanceLevel
    • ReplacementLevel
    • DisposalLevel
  • Pset_ManufacturerOccurrence
    • AcquisitionDate
    • BarCode
    • SerialNumber
    • BatchReference
    • AssemblyPlace
    • ManufacturingDate
  • Pset_ManufacturerTypeInformation
    • GlobalTradeItemNumber
    • ArticleNumber
    • ModelReference
    • ModelLabel
    • Manufacturer
    • ProductionYear
    • AssemblyPlace
    • OperationalDocument
    • SafetyDocument
    • PerformanceCertificate
  • Pset_ProvisionForVoid PROVISIONFORVOID
    • VoidShape
    • Width
    • Height
    • Diameter
    • Depth
    • System
  • Pset_RepairOccurrence
    • RepairContent
    • RepairDate
    • MeanTimeToRepair
  • Pset_Risk
    • RiskName
    • RiskType
    • NatureOfRisk
    • RiskAssessmentMethodology
    • UnmitigatedRiskLikelihood
    • UnmitigatedRiskConsequence
    • UnmitigatedRiskSignificance
    • MitigationPlanned
    • MitigatedRiskLikelihood
    • MitigatedRiskConsequence
    • MitigatedRiskSignificance
    • MitigationProposed
    • AssociatedProduct
    • AssociatedActivity
    • AssociatedLocation
  • Pset_ServiceLife
    • ServiceLifeDuration
    • MeanTimeBetweenFailure
  • Pset_Tolerance
    • ToleranceDescription
    • ToleranceBasis
    • OverallTolerance
    • HorizontalTolerance
    • OrthogonalTolerance
    • VerticalTolerance
    • PlanarFlatness
    • HorizontalFlatness
    • ElevationalFlatness
    • SideFlatness
    • OverallOrthogonality
    • HorizontalOrthogonality
    • OrthogonalOrthogonality
    • VerticalOrthogonality
    • OverallStraightness
    • HorizontalStraightness
    • OrthogonalStraightness
    • VerticalStraightness
  • Pset_Uncertainty
    • UncertaintyBasis
    • UncertaintyDescription
    • HorizontalUncertainty
    • LinearUncertainty
    • OrthogonalUncertainty
    • VerticalUncertainty
  • Pset_Warranty
    • WarrantyIdentifier
    • WarrantyStartDate
    • IsExtendedWarranty
    • WarrantyPeriod
    • WarrantyContent
    • PointOfContact
    • Exclusions
  • Qto_BodyGeometryValidation
    • GrossSurfaceArea
    • NetSurfaceArea
    • GrossVolume
    • NetVolume
    • SurfaceGenusBeforeFeatures
    • SurfaceGenusAfterFeatures

5.4.3.81.6 Concept usage

Concept Usage Description
IfcRoot (2)
IfcObjectDefinition (9)
IfcObject (5)
IfcProduct (18)
IfcElement (44)
Click to show 78 hidden inherited concepts
IfcVirtualElement (3)
Material Single General

It is illegal to assign an IfcMaterial to an IfcVirtualElement with the PredefinedType = PROVISIONFORVOID.

Surface Geometry General

The 3D geometric representation of IfcVirtualElement is defined using a surface geometry. The following constraints apply to the 3D surface representation:

In case of an IfcSurfaceOfLinearExtrusion:

  • Profile: IfcArbitraryOpenProfileDef
  • Extrusion: The extrusion direction shall be vertically, i.e., along the positive Z Axis of the coordinate system of the containing spatial structure element.

In case of an IfcCurveBoundedPlane, IfcCurveBoundedSurface, IfcRectangularTrimmedSurface:

  • Extrusion: The BasisSurface shall be a surface that is upright, i.e. standing perpendicular to the xy place of the coordinate system of the containing spatial structure element.
Property Sets for Objects General

This concept can be applied to the following resources:

Table 5.4.3.81.G

5.4.3.81.7 Formal representation

ENTITY IfcVirtualElement
SUBTYPE OF (IfcElement);
PredefinedType : OPTIONAL IfcVirtualElementTypeEnum;
WHERE
CorrectPredefinedType : NOT(EXISTS(PredefinedType)) OR
(PredefinedType <> IfcVirtualElementTypeEnum.USERDEFINED) OR
((PredefinedType = IfcVirtualElementTypeEnum.USERDEFINED) AND EXISTS (SELF\IfcObject.ObjectType));
END_ENTITY;

5.4.3.81.8 References

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5.4.3.81.9 Changelog

5.4.3.81.9.1 IFC4.3_DEV_738df036

  • attribute, PredefinedType
  • where rule, CorrectPredefinedType