IFC 4.3.x development

5.4.3.57 IfcRelSpaceBoundary1stLevel

Change log

IFC4

added

5.4.3.57.1 Semantic definitions at the entity

The 1st level space boundary defines the physical or virtual delimiter of a space by the relationship IfcRelSpaceBoundary1stLevel to the surrounding elements. 1st level space boundaries are characterizeda by:

  • 1st level space boundaries are the boundaries of a space defined by the surfaces of building elements bounding this space (physical space boundaries) or by virtual surfaces provided by an adjacent space with no dividing wall.
  • 1st level space boundaries do not consider any change of material in the bounding building elements, or different spaces/zones behind a wall or slab (floor or ceiling).
  • 1st level space boundaries are differentiated in two ways: virtual or physical and internal,external, or undefined (internal and external) e.g. for a wall that is partially inside and outside.
  • 1st level space boundaries form a closed shell around the space (so long as the space is completely enclosed) and include overlapping boundaries representing openings (filled or not) in the building elements (see implementers agreement below).

1st level space boundaries define a space by its boundary surfaces without taking anything on the other side of the bounding elements into account.

NOTE  1st level space boundaries are used e.g. in quantity take-off and facility management as they describe the surfaces for finishes. They cannot be directly used for thermal analysis. However 1st level space boundaries can provide the input to preprocessors to thermal analysis software that take 1st level space boundaries and perform the necessary transformation into 2nd level space boundaries that are required for energy analysis.

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.

"<a href=IfcRelSpaceBoundary1stLevel"' src="../figures/ifcrelspaceboundary1stlevel-fig1.png" title="Figure 1 — Space boundary first level relationships"/>

Geometry Use Definitions

See the definition at the supertype IfcRelSpaceBoundary for guidance on using the connection geometry for first level space boundaries.

5.4.3.57.1 Attributes

# Attribute Type Description
IfcRoot
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.
IfcRelationship
IfcRelConnects
IfcRelSpaceBoundary
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 InternalOrExternalBoundaryIfcInternalOrExternalEnum 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
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 ParentBoundaryReference to the inner boundaries of the space boundary. Inner boundaries are defined by the space boundaries of openings, doors and windows.

5.4.3.57.2 Entity inheritance

dot_inheritance IfcRelSpaceBoundary2ndLevel IfcRelSpaceBoundary2ndLevel IfcRelSpaceBoundary1stLevel IfcRelSpaceBoundary1stLevel IfcRelSpaceBoundary2ndLevel->IfcRelSpaceBoundary1stLevel IfcRelSpaceBoundary IfcRelSpaceBoundary IfcRelSpaceBoundary1stLevel->IfcRelSpaceBoundary IfcRelConnects IfcRelConnects IfcRelSpaceBoundary->IfcRelConnects IfcRelConnects_children 15 more... IfcRelConnects_children->IfcRelConnects IfcRelationship IfcRelationship IfcRelConnects->IfcRelationship IfcRelationship_children 5 more... IfcRelationship_children->IfcRelationship IfcRoot IfcRoot IfcRelationship->IfcRoot IfcObjectDefinition IfcObjectDefinition IfcObjectDefinition->IfcRoot IfcPropertyDefinition IfcPropertyDefinition IfcPropertyDefinition->IfcRoot

5.4.3.57.3 Definitions applying to General Usage

5.4.3.57.3.1 Identity

IfcRoot assigns the globally unique ID. In addition it may provide for a name and a description about the concept.

5.4.3.57.3.2 Revision Control

Ownership, history, and merge state is captured using IfcOwnerHistory.

5.4.3.57.4 Formal representations

ENTITY IfcRelSpaceBoundary1stLevel
 SUPERTYPE OF (ONEOF
	(IfcRelSpaceBoundary2ndLevel))
 SUBTYPE OF (IfcRelSpaceBoundary);
	ParentBoundary : OPTIONAL IfcRelSpaceBoundary1stLevel;
 INVERSE
	InnerBoundaries : SET [0:?] OF IfcRelSpaceBoundary1stLevel FOR ParentBoundary;
END_ENTITY;