6.2.3.9 IfcDistributionSystem

6.2.3.9.1 Semantic definition

A distribution system is a network designed to receive, store, maintain, distribute, or control the flow of a distribution media. A common example is a heating hot water system that consists of a pump, a tank, and an interconnected piping system for distributing hot water to terminals.

The group IfcDistributionSystem defines the occurrence of a specialized system for use within the context of building services or utilities for built facilities.

Important functionalities for the description of a distribution system are derived from existing IFC entities:

From IfcSystem it inherits the ability to couple the built system via IfcRelReferencedInSpatialStructure to one or more IfcSpatialElement subtypes as necessary.
From IfcGroup it inherits the inverse attribute IsGroupedBy, pointing to the relationship class IfcRelAssignsToGroup. This allows the grouping of distribution elements (instances of IfcDistributionElement subtypes).
From IfcObjectDefinition it inherits the inverse attribute IsDecomposedBy pointing to the relationship class IfcRelAggregates. It provides the hierarchy between the separate (partial) distribution systems. For example, an electrical main circuit may be aggregated into branch circuits.

6.2.3.9.2 Entity inheritance

6.2.3.9.3 Attributes

#	Attribute	Type	Description
IfcRoot (4)
1	GlobalId	IfcGloballyUniqueId	Assignment of a globally unique identifier within the entire software world.
2	OwnerHistory	OPTIONAL IfcOwnerHistory	Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object, NOTE only the last modification in stored - either as addition, deletion or modification. IFC4-CHANGE The attribute has been changed to be OPTIONAL.
3	Name	OPTIONAL IfcLabel	Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule.
4	Description	OPTIONAL IfcText	Optional description, provided for exchanging informative comments.
IfcObjectDefinition (7)
	HasAssignments	SET [0:?] OF IfcRelAssigns FOR RelatedObjects	Reference to the relationship objects, that assign (by an association relationship) other subtypes of IfcObject to this object instance. Examples are the association to products, processes, controls, resources or groups.
	Nests	SET [0:1] OF IfcRelNests FOR RelatedObjects	References to the decomposition relationship being a nesting. It determines that this object definition is a part within an ordered whole/part decomposition relationship. An object occurrence or type can only be part of a single decomposition (to allow hierarchical strutures only). IFC4-CHANGE The inverse attribute datatype has been added and separated from Decomposes defined at IfcObjectDefinition.
	IsNestedBy	SET [0:?] OF IfcRelNests FOR RelatingObject	References to the decomposition relationship being a nesting. It determines that this object definition is the whole within an ordered whole/part decomposition relationship. An object or object type can be nested by several other objects (occurrences or types). IFC4-CHANGE The inverse attribute datatype has been added and separated from IsDecomposedBy defined at IfcObjectDefinition.
	HasContext	SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions	References to the context providing context information such as project unit or representation context. It should only be asserted for the uppermost non-spatial object. IFC4-CHANGE The inverse attribute datatype has been added.
	IsDecomposedBy	SET [0:?] OF IfcRelAggregates FOR RelatingObject	References to the decomposition relationship being an aggregation. It determines that this object definition is whole within an unordered whole/part decomposition relationship. An object definitions can be aggregated by several other objects (occurrences or parts). IFC4-CHANGE The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.
	Decomposes	SET [0:1] OF IfcRelAggregates FOR RelatedObjects	References to the decomposition relationship being an aggregation. It determines that this object definition is a part within an unordered whole/part decomposition relationship. An object definitions can only be part of a single decomposition (to allow hierarchical strutures only). IFC4-CHANGE The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.
	HasAssociations	SET [0:?] OF IfcRelAssociates FOR RelatedObjects	Reference to the relationship objects, that associates external references or other resource definitions to the object.. Examples are the association to library, documentation or classification.
IfcObject (5)
5	ObjectType	OPTIONAL IfcLabel	The type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes. In particular it holds the user defined type, if the enumeration of the attribute PredefinedType is set to USERDEFINED.
	IsDeclaredBy	SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects	Link to the relationship object pointing to the declaring object that provides the object definitions for this object occurrence. The declaring object has to be part of an object type decomposition. The associated IfcObject, or its subtypes, contains the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes. IFC4-CHANGE New inverse relationship, change made with upward compatibility for file based exchange.
	Declares	SET [0:?] OF IfcRelDefinesByObject FOR RelatingObject	Link to the relationship object pointing to the reflected object(s) that receives the object definitions. The reflected object has to be part of an object occurrence decomposition. The associated IfcObject, or its subtypes, provides the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes. IFC4-CHANGE New inverse relationship, change made with upward compatibility for file based exchange.
	IsTypedBy	SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects	Set of relationships to the object type that provides the type definitions for this object occurrence. The then associated IfcTypeObject, or its subtypes, contains the specific information (or type, or style), that is common to all instances of IfcObject, or its subtypes, referring to the same type. IFC4-CHANGE New inverse relationship, the link to IfcRelDefinesByType had previously be included in the inverse relationship IfcRelDefines. Change made with upward compatibility for file based exchange.
	IsDefinedBy	SET [0:?] OF IfcRelDefinesByProperties FOR RelatedObjects	Set of relationships to property set definitions attached to this object. Those statically or dynamically defined properties contain alphanumeric information content that further defines the object. IFC4-CHANGE The data type has been changed from IfcRelDefines to IfcRelDefinesByProperties with upward compatibility for file based exchange.
IfcGroup (2)
	IsGroupedBy	SET [0:?] OF IfcRelAssignsToGroup FOR RelatingGroup	Reference to the relationship IfcRelAssignsToGroup that assigns the one to many group members to the IfcGroup object. IFC4-CHANGE The cardinality has been changed from 1..1 to 0..? in order to allow the exchange of a group concept without having already group members assigned. It now also allows the use of many instances of IfcRelAssignsToGroup to assign the group members. The change has been done with upward compatibility for file based exchange.
	ReferencedInStructures	SET [0:?] OF IfcRelReferencedInSpatialStructure FOR RelatedElements	No description available.
IfcSystem (2)
	ServicesBuildings	SET [0:1] OF IfcRelServicesBuildings FOR RelatingSystem	Reference to the ~~building~~ spatial structure via the objectified relationship IfcRelServicesBuildings, which is serviced by the system.
	ServicesFacilities	SET [0:?] OF IfcRelReferencedInSpatialStructure FOR RelatedElements	No description available.
Click to show 20 hidden inherited attributes Click to hide 20 inherited attributes
IfcDistributionSystem (2)
6	LongName	OPTIONAL IfcLabel	Long name for a distribution system, used for informal purposes. It should be used, if available, in conjunction with the inherited Name attribute.\X\0D NOTE In many scenarios the Name attribute refers to the short name or number of a distribution system or branch circuit, and the LongName refers to a descriptive name.
7	PredefinedType	OPTIONAL IfcDistributionSystemEnum	A list of types to further identify the object. Some property sets may be specifically applicable to one of these types. NOTE If the object has an associated IfcTypeObject with a PredefinedType, then this attribute shall not be used.

Table 6.2.3.9.B

6.2.3.9.4 Formal propositions

Name	Description
CorrectPredefinedType	Either the PredefinedType attribute is unset, or the inherited attribute ObjectType shall be provided, if the PredefinedType is set to USERDEFINED.
`NOT(EXISTS(PredefinedType)) OR (PredefinedType <> IfcDistributionSystemEnum.USERDEFINED) OR ((PredefinedType = IfcDistributionSystemEnum.USERDEFINED) AND EXISTS (SELF\IfcObject.ObjectType))`

Table 6.2.3.9.C

6.2.3.9.5 Property sets

Pset_Condition
- AssessmentDate
- AssessmentCondition
- AssessmentDescription
- AssessmentType
- AssessmentMethod
- LastAssessmentReport
- NextAssessmentDate
- AssessmentFrequency
Pset_DistributionSystemCommon
- Reference
Pset_DistributionSystemTypeElectrical ELECTRICAL
- ElectricalSystemType
- ElectricalSystemCategory
- Diversity
- NumberOfLiveConductors
- MaximumAllowedVoltageDrop
- NetImpedance
- RatedVoltageRange
Pset_DistributionSystemTypeOverheadContactlineSystem OVERHEAD_CONTACTLINE_SYSTEM
- SpanNominalLength
- ContactWireStagger
- ContactWireNominalDrop
- PressureRange
- ContactWireNominalHeight
- ContactWireUplift
- ElectricalClearance
- NumberOfOverlappingSpans
- PantographType
- TensionLength
- OCSType
Pset_DistributionSystemTypeVentilation VENTILATION
- DesignName
- DuctSizingMethod
- PressureClass
- LeakageClass
- FrictionLoss
- ScrapFactor
- DuctSealant
- MaximumVelocity
- AspectRatio
- MinimumHeight
- MinimumWidth
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_PowerControlSystem ELECTRICAL
- AssemblyInstruction
Pset_ProcessCapacity
- ProcessItem
- ProcessCapacity
- ProcessPerformance
- DownstreamConnections
- UpstreamConnections
Pset_RepairOccurrence
- RepairContent
- RepairDate
- MeanTimeToRepair
Pset_Risk
- RiskName
- RiskType
- NatureOfRisk
- RiskAssessmentMethodology
- UnmitigatedRiskLikelihood
- UnmitigatedRiskConsequence
- UnmitigatedRiskSignificance
- MitigationPlanned
- MitigatedRiskLikelihood
- MitigatedRiskConsequence
- MitigatedRiskSignificance
- MitigationProposed
- AssociatedProduct
- AssociatedActivity
- AssociatedLocation
Pset_ServiceLifeFactors
- QualityOfComponents
- DesignLevel
- WorkExecutionLevel
- IndoorEnvironment
- OutdoorEnvironment
- InUseConditions
- MaintenanceLevel
Pset_TractionPowerSystem ELECTRICAL
- PowerSupplyMode
- ElectrificationType
- RatedFrequency
- NominalVoltage

6.2.3.9.6 Concept usage

Instance diagram for electrical circuit — Figure 6.2.3.9.A — Distribution system assignment

Concept	Usage	Description
IfcRoot (2)
Revision Control	General	Ownership, history, and merge state is captured using IfcOwnerHistory.
Software Identity	General	IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.
IfcObjectDefinition (9)
Aggregation	General	No description available.
Approval Association	General	No description available.
Classification Association	General	Any object occurrence or object type can have a reference to a specific classification reference, i.e. to a particular facet within a classification system.
Constraint Association	General	No description available.
Document Association	General	No description available.
Library Association	General	No description available.
Material Association	General	No description available.
Material Single	General	No description available.
Nesting	General	No description available.
IfcObject (5)
Assignment to Group	General	No description available.
Object Predefined Type	General	No description available.
Object Typing	General	Any object occurrence can be typed by being assigned to a common object type utilizing this concept. A particular rule, restricting the applicable subtypes of IfcTypeObject that can be assigned, is introduced by overriding this concept at the level of subtypes of IfcObject. This concept can be applied to the following resources: IfcTypeObject
Object User Identity	General	An attribute Name and optionally Description can be used for all subypes of IfcObject. For those subtypes, that have an object type definition, such as ifcBeam - IfcBeamType, the common Name and optionally Description is associated with the object type.
Property Sets with Override	General	Any object occurrence can hold property sets, either directly at the object occurrence as element specific property sets, or at the object type, as type property sets. In this case, the properties that are provided to the object occurrence are the combinations of element specific and type properties. In case, that the same property (within the same property set, is defined both, in occurrence and type properties, the property value of the occurrence property overrides the property value of the type property.
IfcGroup (2)
Group Assignment	General	The IfcGroup establishes an arbitrary collection of objects through utilizing this concept.
Property Sets for Objects	General	This concept can be applied to the following resources: Pset_Risk
IfcSystem (2)
Property Sets for Objects	General	This concept can be applied to the following resources: Pset_Condition Pset_InstallationOccurrence Pset_MaintenanceStrategy Pset_MaintenanceTriggerCondition Pset_MaintenanceTriggerDuration Pset_MaintenanceTriggerPerformance Pset_RepairOccurrence Pset_ServiceLifeFactors
System Element Attributes	General	No description available.
Click to show 20 hidden inherited concepts Click to hide 20 inherited concepts
IfcDistributionSystem (2)
Group Assignment	General	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 6.2.3.9.A — Distribution system assignment Figure 6.2.3.9.A — Distribution system assignment
Property Sets for Objects	General	This is a further elaboration on an inherited concept. This concept can be applied to the following resources: Pset_ProcessCapacity Pset_DistributionSystemTypeElectrical (only applies to `ELECTRICAL)` Pset_PowerControlSystem (only applies to `ELECTRICAL)` Pset_TractionPowerSystem (only applies to `ELECTRICAL)` Pset_DistributionSystemTypeOverheadContactlineSystem (only applies to `OVERHEAD_CONTACTLINE_SYSTEM)` Pset_DistributionSystemTypeVentilation (only applies to `VENTILATION)` Pset_DistributionSystemCommon

6.2.3.9.7 Formal representation

ENTITY IfcDistributionSystem
 SUPERTYPE OF (ONEOF
	(IfcDistributionCircuit))
 SUBTYPE OF (IfcSystem);
	LongName : OPTIONAL IfcLabel;
	PredefinedType : OPTIONAL IfcDistributionSystemEnum;
 WHERE
	CorrectPredefinedType : NOT(EXISTS(PredefinedType)) OR
 (PredefinedType <> IfcDistributionSystemEnum.USERDEFINED) OR
 ((PredefinedType = IfcDistributionSystemEnum.USERDEFINED) AND EXISTS (SELF\IfcObject.ObjectType));
END_ENTITY;