A space is (if specified) associated to a building storey (or in case of exterior spaces to a site). A space may span over several connected spaces. Therefore a space group provides for a collection of spaces included in a storey. A space can also be decomposed in parts, where each part defines a partial space. This is defined by the composition type attribute of the supertype IfcSpatialStructureElement which is interpreted as follow:

• COMPLEX = space group
• ELEMENT = space
• PARTIAL = partial space

The following guidelines should apply for using the Name, Description, LongName and ObjectType attributes.

• Name holds the unique name (or space number) from the plan.
• Description holds any additional information field the user may have specified, there are no further recommendations.
• LongName holds the full name of the space, it is often used in addition to the Name, if a number is assigned to the room, than the descriptive name is exchanged as LongName.
• ObjectType holds the space type, i.e. usually the functional category of the space .

The quantities relating to the space are defined by the IfcElementQuantity and attached by the IfcRelDefinesByProperties. The following quantities are foreseen, but will be subjected to the local standard of measurement:

HISTORY New Entity in IFC Release 1.0

Use case:

The following figure describes the heights and elevations of the IfcSpace.

Geometry Use Definitions

The geometric representation of IfcSpace is given by the IfcProductDefinitionShape and IfcLocalPlacement allowing multiple geometric representations.

NOTE1 If the surrounding instances of IfcRelSpaceBoundary define a complete geometric representation of a particular representation view for that space, than this view shall be omitted from the multiple representations of IfcSpace.

NOTE2 In cases of inconsistency between the geometric representation of the IfcSpace and its surrounding IfcRelSpaceBoundary, the geometric representation of the space should take priority over the geometric representation of the surrounding space boundaries.

Local Placement

The local placement for IfcSpace is defined in its supertype IfcProduct. It is defined by the IfcLocalPlacement, which defines the local coordinate system that is referenced by all geometric representations.

• The PlacementRelTo relationship of IfcLocalPlacement shall point to the local placement of the IfcSpatialStructureElement of type "IfcBuildingStorey", if relative placement is used, or of type "IfcSpace" (e.g. to position a space relative to a space group, or a partial space to a space).
• If the relative placement is not used, the absolute placement is defined within the world coordinate system.

Geometric Representations

Currently, the use of a 2D 'FootPrint' representation of type 'Curve2D' or 'GeometricCurveSet' and a 3D 'Body' representation of type 'SweptSolid, 'Clipping' and 'Brep' is supported.

Two-dimensional Representation using foot print representation

The 2D geometric representation of IfcSpace is defined using the 'Curve2D' or 'GeometricCurveSet' geometry. The following attribute values should be inserted

• IfcShapeRepresentation.RepresentationIdentifier = 'FootPrint'.
• IfcShapeRepresentation.RepresentationType = 'Curve2D' or 'GeometricCurveSet' .

The following constraints apply to the 2D representation:

• Profile: IfcBoundedCurve is required, using IfcPolyline for faceted space contours or IfcCompositeCurve for space contours with arc segments.

Two-dimensional bounded curve representing the foot print of IfcSpace.

Standard Geometric Representation using Swept Solid representation

The standard geometric representation of IfcSpace is defined using the swept area solid geometry. The following attribute values should be inserted

• IfcShapeRepresentation.RepresentationIdentifier = 'Body'.
• IfcShapeRepresentation.RepresentationType = 'SweptSolid'.

The following constraints apply to the standard representation:

• Solid: IfcExtrudedAreaSolid is required,
• Profile: IfcArbitraryClosedProfileDef is required, IfcArbitraryProfileDefWithVoids shall be supported.
• Extrusion: The extrusion direction shall be vertically, i.e., along the positive Z Axis of the co-ordinate system of the containing spatial structure element.

Extrusion of an arbitrary profile definition with voids into the swept area solid of IfcSpace.

Advanced Geometric Representation using Clipping representation

The advanced geometric representation of IfcSpace is defined using the swept area solid geometry that can be subjected to a Boolean expression. The following attribute values should be inserted.

• IfcShapeRepresentation.RepresentationIdentifier = 'Body'.
• IfcShapeRepresentation.RepresentationType = 'Clipping'.

The following additional constraints apply to the advanced representation:

• Solid: see standard geometric representation,
• Profile: see standard geometric representation,
• Extrusion: see standard geometric representation,
• Boolean result: The difference operation with the second operand being of type IfcHalfSpaceSolid (or one of its subtypes) shall be supported.

Extrusion of an arbitrary profile definition into the swept area solid. The solid and an half space solid are operands of the Boolean result of IfcSpace.