A space represents an area or volume bounded actually or theoretically. Spaces are areas or volumes that provide for certain functions within a building.

A space is 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 CompositionType attribute of the supertype IfcSpatialStructureElement which is interpreted as follow:

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

NOTE  View definitions and implementation agreements may restrict spaces with CompositionType=ELEMENT to be non-overlapping.

The IfcSpace is used to build the spatial structure of a building (that serves as the primary project breakdown and is required to be hierarchical). The spatial structure elements are linked together by using the objectified relationship IfcRelAggregates.

Figure 185 shows the IfcSpace as part of the spatial structure. It also serves as the spatial container for space related elements.

NOTE  Detailed requirements on mandatory element containment and placement structure relationships are given in view definitions and implementer agreements.

Figure 185 — Space composition

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, then the descriptive name is exchanged as LongName.
• ObjectType holds the space type, i.e. usually the functional category of the space .

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

Figure 186 describes the heights and elevations of the IfcSpace.

• elevation of the space (top of construction slab) equals elevation of storey: provided by IfcBuildingStorey.Elevation relative to em>IfcBuilding.ElevationOfRefHeight
• elevation of the space flooring (top of flooring on top of slab): provided by IfcSpace.ElevationWithFlooring relative to IfcBuilding.ElevationOfRefHeight
• height of space (top of slab below to bottom of slab above): provided by BaseQuantity with Name="Height"
• floor height of space (top of slab below to top of flooring): provided by BaseQuantity with Name="FinishFloorHeight"
• net height of space (top of flooring to bottom of suspended ceiling): provided by BaseQuantity with Name="FinishCeilingHeight"

Figure 186 — Space elevations

HISTORY  New entity in IFC1.0

The Spatial Composition concept applies to this entity.

By using the inverse relationship IfcSpace.IsDecomposedBy it references IfcSpace by IfcRelAggregates.RelatedObjects. If it refers to another instance of IfcSpace, the referenced IfcSpace needs to have a different and lower CompositionType, i.e. ELEMENT (if the other IfcSpace has COMPLEX), or PARTIAL (if the other IfcSpace has ELEMENT).

The Spatial Decomposition concept applies to this entity.

By using the inverse relationship IfcSpace.Decomposes it references IfcSite || IfcBuildingStorey || IfcSpace by IfcRelAggregates.RelatingObject. If it refers to another instance of IfcSpace, the referenced IfcSpace needs to have a different and higher CompositionType, i.e. COMPLEX (if the other IfcSpace has ELEMENT), or ELEMENT (if the other IfcSpace has PARTIAL).

The Spatial Container concept applies to this entity.

If there are building elements and/or other elements directly related to the IfcSpace (like most furniture and distribution elements), they are associated with the IfcSpace by using the objectified relationship IfcRelContainedInSpatialStructure. The IfcSpace references them by its inverse relationship:

• IfcSpace.ContainsElements -- referencing any subtype of IfcProduct (with the exception of other spatial structure element) by IfcRelContainedInSpatialStructure.RelatedElements.

The Property Sets for Objects concept template applies to this entity as shown in Table 68.

The Quantity Sets concept template applies to this entity as shown in Table 69.

The Space Boundaries 1st Level concept applies to this entity.

The Space Boundaries 2nd Level concept applies to this entity.

The Product Local Placement concept applies to this entity.

The local placement for IfcSpace is defined at 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 or IfcSite if relative placement is used.
• If the relative placement is not used, the absolute placement is defined within the world coordinate system.

The FootPrint GeomSet Geometry concept template applies to this entity as shown in Table 70.

The following constraints apply to the 2D representation:

• An IfcBoundedCurve is required, using IfcPolyline for faceted space contours or IfcCompositeCurve for space contours with arc segments. For spaces with inner boundaries, a set of IfcBoundedCurve's is used, that should be grouped into an IfcGeometricCurveSet.

	EXAMPLE  Figure 186 shows a two-dimensional bounded curve representing the foot print of IfcSpace.
Figure 186 — Space footprint

The Body SweptSolid Geometry concept applies to this entity.

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.

Figure 187 shows an extrusion of an arbitrary profile definition with voids into the swept area solid of IfcSpace.

Figure 187 — Space body swept solid

The Body Clipping Geometry concept applies to this entity.

The following additional constraints apply to the advanced 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.
• Boolean result: The difference operation with the second operand being of type IfcHalfSpaceSolid (or one of its subtypes) shall be supported.

Figure 188 shows an 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.

Figure 188 — Space body clipping

The Body Brep Geometry concept applies to this entity.

The space can be represented by a brep geometry representation