#### 6.1.3.6 IfcDistributionSystem

| Système de distribution
| haustechnische Anlage

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.

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

- From IfcSystem it inherits the ability to couple the distribution system via IfcRelServicesBuildings to one or more IfcSpatialElement subtypes as necessary.

- From IfcGroup it inherits the inverse attribute IsGroupedBy, pointing to the relationship entity IfcRelAssignsToGroup. This allows to group distribution elements (instances of IfcDistributionElement subtypes), and in special cases ports directly (instances of IfcDistributionPort).

- From IfcObject it inherits the inverse attribute IsDecomposedBy pointing to the relationship entity IfcRelAggregates. It provides the hierarchy between the separate (partial) distribution systems. For example, an electrical main circuit may be aggregated into branch circuits.

> HISTORY New entity in IFC4.

> IFC4 CHANGE For electrical power systems, IfcElectricalCircuit has been used for low-voltage (12-1000 V) power circuits and has been replaced by IfcDistributionCircuit in IFC4; IfcDistributionSystem with PredefinedType 'ELECTRICAL' should be used for overall power systems, and IfcDistributionCircuit with PredefinedType 'ELECTRICAL' should be used for each switched circuit.

## Building Automation

A project may include many distribution systems, such as for air conditioning, electrical, domestic cold water, security, etc. This MVD is focused on control systems, where IfcDistributionSystem having PredefinedType=CONTROL is of particular interest.

Systems may contain a flat list of devices (or control points), or a logical hierarchy of partitions, each containing subsets of devices. Each object has a Name that may be used for human identification (though not necessarily unique machine identification), an optional Description, an optional Type, and extensible properties.

Control points within a system are represented by IfcDistributionElement subtypes, with IfcController as the default type for raw analog or digital I/O. Many protocols such as OPC expose raw control points (digital or analog values with read and/or write access, without identification of device types). Other protocols may identify types of objects by predefined type codes (such as BACnet and SNMP) where the available properties can be deduced by the type code. Other protocols may provide extensible type codes that correspond to a domain registry which may be updated over time (such as USB, UPnP, UPB, and Insteon) where device types can be determined by matching codes with product types found in referenced product libraries. Yet other protocols may include the type information directly (such as oBIX).

If the control system forms a logical hierarchy of devices and has a concept of branch nodes or folders (such as OPC or oBIX), then such groupings may be represented by IfcZone, each of which may have assigned devices or sub-zones.

For control systems that support device detection, the classification hierarchy may be detected from the system and automatically constructed; in the absence of auto-detection, addresses may be manually specified by a user.

For control systems that support type information, specific instances of products or groups may be automatically created and linked to classification and type information; in the absence of such information, such links may be manually specified by a user.

The following concepts are inherited at supertypes:

- IfcRoot: Revision Control
- IfcSystem: Table Mapping

Instance diagram

Classification

The Classification concept applies to this entity.

Exchange |  |  |  |  |
--- | --- | --- | --- | --- | ---
Import |  |  |  |  |
Export |  |  |  |  |

Object Aggregation

The Object Aggregation concept applies to this entity as shown in Table 40.

PredefinedType | RelatedObjects | Description
--- | --- | ---
CONTROL | IfcDistributionSystem | Control systems may be organized according to a hierarchy as supported by the particular control system, where each subsystem represents a logical and/or physical grouping.
Table 40 — IfcDistributionSystem Object Aggregation

Exchange |  |  |  |  |
--- | --- | --- | --- | --- | ---
Import |  |  |  |  |
Export |  |  |  |  |

Group Assignment

The Group Assignment concept applies to this entity as shown in Table 41.

Type | Description
--- | ---
IfcDistributionElement | A control system may have assigned device instances either as a flat list, or assigned at aggregated subsystems.
Table 41 — IfcDistributionSystem Group Assignment

Exchange |  |  |  |  |
--- | --- | --- | --- | --- | ---
Import |  |  |  |  |
Export |  |  |  |  |

XSD Specification:

<xs:element name="IfcDistributionSystem" type="ifc:IfcDistributionSystem" substitutionGroup="ifc:IfcSystem" nillable="true"/>
<xs:complexType name="IfcDistributionSystem">
<xs:complexContent>
<xs:extension base="ifc:IfcSystem"/>
</xs:complexContent>
</xs:complexType>

EXPRESS Specification:

ENTITY IfcDistributionSystem

| SUPERTYPE OF()

| SUBTYPE OF IfcSystem;

LongName | : | OPTIONAL IfcLabel;
PredefinedType | : | OPTIONAL IfcDistributionSystemEnum;

END_ENTITY;

EXPRESS-G diagram

Attribute Definitions:

LongName | : | Long name for a system, used for informal purposes. It should be used, if available, in conjunction with the inherited Name attribute. 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.
PredefinedType | : | Predefined types of distribution systems.

Inheritance Graph:

ENTITY IfcDistributionSystem

| ENTITY IfcRoot

GlobalId | : | IfcGloballyUniqueId;
OwnerHistory | : | OPTIONAL IfcOwnerHistory;
Name | : | OPTIONAL IfcLabel;
Description | : | OPTIONAL IfcText;

| ENTITY IfcObjectDefinition

| INVERSE

HasAssignments | : | SET OF IfcRelAssigns FOR RelatedObjects;
Nests | : | SET [0:1] OF IfcRelNests FOR RelatedObjects;
IsNestedBy | : | SET OF IfcRelNests FOR RelatingObject;
HasContext | : | SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;
IsDecomposedBy | : | SET OF IfcRelAggregates FOR RelatingObject;
Decomposes | : | SET [0:1] OF IfcRelAggregates FOR RelatedObjects;
HasAssociations | : | SET OF IfcRelAssociates FOR RelatedObjects;

| ENTITY IfcObject

ObjectType | : | OPTIONAL IfcLabel;

| INVERSE

IsDeclaredBy | : | SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects;
Declares | : | SET OF IfcRelDefinesByObject FOR RelatingObject;
IsTypedBy | : | SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects;
IsDefinedBy | : | SET OF IfcRelDefinesByProperties FOR RelatedObjects;

| ENTITY IfcGroup

| INVERSE

IsGroupedBy | : | SET OF IfcRelAssignsToGroup FOR RelatingGroup;

| ENTITY IfcSystem

| INVERSE

| ENTITY IfcDistributionSystem

LongName | : | OPTIONAL IfcLabel;
PredefinedType | : | OPTIONAL IfcDistributionSystemEnum;

END_ENTITY;

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