IfcSpace
Definition from IAI: 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 (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:
The following guidelines should apply for using the Name, Description, LongName and ObjectType attributes.
HISTORY New Entity in IFC Release 1.0
Property Set Use Definition:
The property sets relating to the IfcSpace are defined by the IfcPropertySet and attached by the IfcRelDefinesByProperties relationship. It is accessible by the inverse IsDefinedBy relationship. The following property set definitions specific to the IfcSpace are part of this IFC release:
Quantity Use Definition:
The quantities relating to the IfcSpace 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:
Name  Description  Value Type 
AverageHeight  Floor Height (without flooring) to Ceiling height (without suspended ceiling) for this space (measured from top of slab of this space to the bottom of slab of space above); the average shall be taken if room shape is not prismatic.  IfcQuantityLength 
AverageGrossHeight  Floor Height to Floor Height for this space (measured from top of slab of this space to top of slab of space above); the average shall be taken if room shape is not prismatic.  IfcQuantityLength 
AverageClearHeight  Clear Height between floor level (including finish) and ceiling level (including finish and sub construction) of this space; the average shall be taken if room shape is not prismatic.  IfcQuantityLength 
GrossPerimeter  Calculated gross perimeter at the floor level of this space. It all sides of the space, including those parts of the perimeter that are created by virtual boundaries and openings. The exact definition and calculation rules depend on the method of measurement used.  IfcQuantityLength 
NetPerimeter  Calculated net perimeter at the floor level of this space. It normally excludes those parts of the perimeter that are created by by virtual boundaries and openings. The exact definition and calculation rules depend on the method of measurement used.  IfcQuantityLength 
GrossFloorArea  Calculated sum of all floor areas covered by the space. It normally includes the area covered by elements inside the space (columns, inner walls, etc.). The exact definition and calculation rules depend on the method of measurement used.  IfcQuantityArea 
NetFloorArea  Calculated sum of all usable floor areas covered by the space. It normally excludes the area covered by elements inside the space (columns, inner walls, etc.), floor openings, or other protruding elements. Special rules apply for areas that have a low headroom. The exact definition and calculation rules depend on the method of measurement used.  IfcQuantityArea 
GrossCeilingArea  Calculated sum of all ceiling areas of the space. It normally includes the area covered by elements inside the space (columns, inner walls, etc.). The ceiling area is the real (and not the projected) area (e.g. in case of sloped ceilings). The exact definition and calculation rules depend on the method of measurement used.  IfcQuantityArea 
NetCeilingArea  Calculated sum of all ceiling areas covered by the space. It normally excludes the area covered by elements inside the space (columns, inner walls, etc.) or by ceiling openings. The ceiling area is the real (and not the projected) area (e.g. in case of sloped ceilings). The exact definition and calculation rules depend on the method of measurement used.  IfcQuantityArea 
GrossWallArea  Calculated sum of all wall areas bounded by the space. It normally includes the area covered by elements inside the wall area (doors, windows, other openings, etc.). The exact definition and calculation rules depend on the method of measurement used.  IfcQuantityArea 
NetWallArea  Calculated sum of all wall areas bounded by the space. It normally excludes the area covered by elements inside the wall area (doors, windows, other openings, etc.). Special rules apply for areas that have a low headroom. The exact definition and calculation rules depend on the method of measurement used.  IfcQuantityArea 
GrossVolume  Calculated gross volume of all areas enclosed by the space (normally including the volume of construction elements inside the space). The exact definition and calculation rules depend on the method of measurement used.  IfcQuantityVolume 
NetVolume  Calculated net volume of all areas enclosed by the space (normally excluding the volume of construction elements inside the space). The exact definition and calculation rules depend on the method of measurement used.  IfcQuantityVolume 
Spatial Structure Use Definition
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. The IfcSpace references them by its inverse relationships:
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, then 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.
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.
'Foot' Print representation
The 2D geometric representation of IfcSpace is defined using the 'Curve2D' or 'GeometricCurveSet' geometry. The following attribute values should be inserted
The following constraints apply to the 2D representation:
Twodimensional bounded curve representing the foot print of IfcSpace. 
'Swept Solid' representation
The standard geometric representation of IfcSpace is defined using the swept area solid geometry. The following attribute values should be inserted
The following constraints apply to the standard representation:
Extrusion of an arbitrary profile definition with voids into the swept area solid of IfcSpace. 
'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.
The following additional constraints apply to the advanced representation:
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. 
'Brep' representation
The fallback advanced geometric representation of IfcSpace is defined using the Brep solid geometry. may be represented as a single or multiple instances of IfcFacetedBrep or IfcFacetedBrepWithVoids. The Brep representation allows for the representation of complex element shape. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:
EXPRESS specification:

InteriorOrExteriorSpace  :  Defines, whether the Space is interior (Internal), or exterior (External), i.e. part of the outer space. 
ElevationWithFlooring  :  Level of flooring of this space; the average shall be taken, if the space ground surface is sloping or if there are level differences within this space. 
HasCoverings  : 
Reference to IfcCovering by virtue of the objectified relationship IfcRelCoversSpaces. It defines the concept of a space having coverings assigned. Those coverings may represent different flooring, or tiling areas.
NOTE Coverings are often managed by the space, and not by the building element, which they cover. 
BoundedBy  :  Reference to Set of Space Boundaries that defines the physical or virtual delimitation of that Space. 
