The 2nd level space boundary defines the physical or virtual delimiter of a space by the relationship IfcRelSpaceBoundary2ndLevel to the surrounding elements. 2nd level space boundaries are characterized by:
2nd level space boundaries define the heat transfer surfaces on both sides of building elements that separate spaces. The generation of 2nd level space boundaries has to take building elements and spaces on the other side into account.
NOTE 2nd level space boundaries are used by many analysis packages that require a surface view of the building that can be transformed into the various simple topological models. Examples of such analysis packages include: (1) energy analysis, (2) lighting analysis, (3) fluid dynamics
HISTORY New entity in IFC4.
Relationship Use Definitions
As shown in Figure 1, the attribute ParentBoundary with inverse InnerBoundaries is provided to link the space boundaries of doors, windows, and openings to the parent boundary, such as of a wall or slab.
NOTE The space boundary of the parent is not cut by the inner boundary - both overlap.
The attribute CorrespondingBoundary with inverse Corresponds is provided to link the pair of space boundaries on the opposite sides of the building element.
NOTE Only 2nd level space boundaries of type A have corresponding boundaries.
IfcRelSpaceBoundary2ndLevel"' src="../figures/ifcrelspaceboundary2ndlevel-fig1.png" title="Figure 1 — Space boundary second level relationships"/>
Geometry Use Definitions
See the definition at the supertype IfcRelSpaceBoundary for guidance on using the connection geometry for second level space boundaries.
|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.|
|5||RelatingSpace||IfcSpaceBoundarySelect||Reference to one spaces that is delimited by this boundary.|
|6||RelatedBuildingElement||IfcElement||Reference to ~~Building~~ Element, that defines the Space Boundaries.|
> IFC2x CHANGE The data type has been changed from IfcBuildingElement to IfcElement with upward compatibility for file based exchange.
> IFC4 CHANGE The attribute has been changed to be mandatory.
|7||ConnectionGeometry||OPTIONAL IfcConnectionGeometry||Physical representation of the space boundary. Provided as a **curve or** surface given within the LCS of the space.|
> IFC2x CHANGE The data type has been changed from IfcConnectionSurfaceGeometry to IfcConnectionGeometry with upward compatibility for file based exchange.
|8||PhysicalOrVirtualBoundary||IfcPhysicalOrVirtualEnum||Defines, whether the Space Boundary is physical (Physical) or virtual (Virtual).|
|9||InternalOrExternalBoundary||IfcInternalOrExternalEnum||Defines, whether the Space Boundary is internal (Internal), or external, i.e. adjacent to open space (that can be an partially enclosed space, such as terrace (External).|
|10||ParentBoundary||OPTIONAL IfcRelSpaceBoundary1stLevel||Reference to the host, or parent, space boundary within which this inner boundary is defined.|
|InnerBoundaries||SET [0:?] OF IfcRelSpaceBoundary1stLevel FOR ParentBoundary||Reference to the inner boundaries of the space boundary. Inner boundaries are defined by the space boundaries of openings, doors and windows.|
|11||CorrespondingBoundary||OPTIONAL IfcRelSpaceBoundary2ndLevel||Reference to the other space boundary of the pair of two space boundaries on either side of a space separating thermal boundary element.|
|Corresponds||SET [0:1] OF IfcRelSpaceBoundary2ndLevel FOR CorrespondingBoundary||Reference to the other space boundary of the pair of two space boundaries on either side of a space separating thermal boundary element.|
IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.
Ownership, history, and merge state is captured using IfcOwnerHistory.
ENTITY IfcRelSpaceBoundary2ndLevel SUBTYPE OF (IfcRelSpaceBoundary1stLevel); CorrespondingBoundary : OPTIONAL IfcRelSpaceBoundary2ndLevel; INVERSE Corresponds : SET [0:1] OF IfcRelSpaceBoundary2ndLevel FOR CorrespondingBoundary; END_ENTITY;