IFC 4.3.0.1 (IFC4X3) development

5.4.3.61 IfcRelSpaceBoundary2ndLevel

5.4.3.61.1 Semantic definition

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 still represent building elements that bound the space, but are more granular in that they are subdivided in any of the following cases:
    • Differences in materials and/or material assemblies (for example, a wainscot or paneling on the lower portion of a wall).
    • Differences in spaces or zones on the other side of the building element (or virtual boundary) represented by the space boundary (for example, two different spaces on the other side of a wall)
  • 2nd level space boundaries are differentiated in two ways: virtual or physical and internal or external, whereby any space boundary that is both internal and external has to be split into segments being either or.
  • 2nd level space boundaries represent both sides of a heat transfer surface separated by the thickness of the building element. They can be further differentiated in:
    • Type 2a that occurs when there is a space on the opposite side of the building element providing the space boundary
    • Type 2b occurs if there is a building element on the opposite side of the building element providing the space boundary.
  • The connection geometry of 2nd level space boundaries is restricted to planar surfaces only. This means that curved surfaces must be segmented.

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.

Relationship Use Definitions

As shown in Figure 5.4.3.61.A, 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.

The attribute CorrespondingBoundary with inverse Corresponds is provided to link the pair of space boundaries on the opposite sides of the building element.

IfcRelSpaceBoundary2ndLevel
Figure 5.4.3.61.A — 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.

5.4.3.61.2 Entity inheritance

5.4.3.61.3 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,

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.

IfcRelSpaceBoundary (5)
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.

7 ConnectionGeometry OPTIONAL IfcConnectionGeometry

Physical representation of the space boundary. Provided as a curve or surface given within the LCS of the space.

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).

IfcRelSpaceBoundary1stLevel (2)
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.

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IfcRelSpaceBoundary2ndLevel (2)
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.

Table 5.4.3.61.B

5.4.3.61.4 Concept usage

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.

Click to show 2 hidden inherited concepts Click to hide 2 inherited concepts
Table 5.4.3.61.C

5.4.3.61.5 Formal representation

ENTITY IfcRelSpaceBoundary2ndLevel
 SUBTYPE OF (IfcRelSpaceBoundary1stLevel);
	CorrespondingBoundary : OPTIONAL IfcRelSpaceBoundary2ndLevel;
 INVERSE
	Corresponds : SET [0:1] OF IfcRelSpaceBoundary2ndLevel FOR CorrespondingBoundary;
END_ENTITY;

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5.4.3.61.6 Changelog

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