A building represents a structure that provides shelter for
its occupants or contents and stands in one place. The
building is also used to provide a basic element within the
spatial structure hierarchy for the components of a building
project (together with site, storey, and space).
NOTE Definition from ISO 6707-1:
that has the provision of shelter for its occupants or
contents as one of its main purpose and is normally designed
to stand permanently in one place.
A building is (if specified) associated to a site. A building
may span over several connected or disconnected buildings.
Therefore building complex provides for a collection of
buildings included in a site. A building can also be
decomposed in (vertical) parts, where each part defines a
building section. This is defined by the composition type
attribute of the supertype IfcSpatialStructureElements
which is interpreted as follow:
- COMPLEX: building complex
- ELEMENT: building
- PARTIAL: building section
The IfcBuilding 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
HISTORY New entity in IFC1.0.
Figure 111 shows the IfcBuilding as part of the spatial
structure. It also serves as the spatial container for
building and other elements.
NOTE Detailed requirements on mandatory element containment
and placement structure relationships are given in view
definitions and implementer agreements.
Figure 111 — Building composition
Systems, such as building service or electrical distribution
systems, zonal systems, or structural analysis systems,
relate to IfcBuilding by using the objectified
Attribute Use Definition
Figure 112 describes the heights and elevations of the
IfcBuilding. It is used to provide the height above
sea level of the project height datum for this building, that
is, the internal height 0.00. The height 0.00 is often used
as a building internal reference height and equal to the
floor finish level of the ground floor.
- base elevation of building provided by:
IfcBuilding.ElevationOfRefHeight, it is usually the
top of construction slab
- base elevation of terrain at the perimeter of the
building provided by: IfcBuilding.ElevationOfTerrain,
it is usually the minimum elevation is sloped terrain
- total height of building, also referred to as ridge
height (top of roof structure, e.g the ridge against
terrain): provided by BaseQuantity with Name="TotalHeight"
- eaves height of building (base of roof structure, e.g the
eaves against terrain): provided by BaseQuantity with
Figure 112 — Building elevations
Common Use Definitions
The following concepts are inherited at supertypes:
The Spatial Composition concept applies to this entity as shown in Table 23.
|IfcProject||Direct assignment to project, if the building is the outermost spatial container, and no site information is provided for building projects|
|IfcSite||Assignment to site, if the building is the spatial container for the building project with site information |
|IfcBuilding||Assignment to another building as spatial container, e.g. if this building represents a building section.|
Table 23 — IfcBuilding Spatial Composition
NOTE By using the inverse relationship IfcBuilding.Decomposes it references IfcProject || IfcSite || IfcBuilding through IfcRelAggregates.RelatingObject. If it refers to
another instance of IfcBuilding, the referenced IfcBuilding needs to have a different
and higher CompositionType, i.e. COMPLEX (if the other IfcBuilding has ELEMENT), or
ELEMENT (if the other IfcBuilding has PARTIAL).
The Spatial Decomposition concept applies to this entity as shown in Table 24.
|IfcBuildingStorey||Spatial decomposition into building stories.|
|IfcBuilding||Spatial decomposition into other buildings, e.g. if this building represents a complex building that is subdivided into building sections. |
Table 24 — IfcBuilding Spatial Decomposition
NOTE By using the inverse relationship IfcBuilding.IsDecomposedBy it references
IfcBuilding || IfcBuildingStorey through IfcRelAggregates.RelatedObjects.
If it refers to another instance of IfcBuilding, the referenced IfcBuilding needs
to have a different and lower CompositionType, i.e. ELEMENT (if the other IfcBuilding
has COMPLEX), or PARTIAL (if the other IfcBuilding has ELEMENT).
The Spatial Container concept applies to this entity as shown in Table 25.
|IfcElement||Physical elements contained in the building.|
|IfcAnnotation||Annotations that are directly related to the building.|
|IfcGrid||Grids that are directly related to the building.|
Table 25 — IfcBuilding Spatial Container
NOTE If there are building elements and/or other elements directly related to the IfcBuilding (like a curtain wall spanning several stories), they are associated with the IfcBuilding by using the objectified relationship IfcRelContainedInSpatialStructure. The IfcBuilding references them by its inverse relationship:
IfcBuilding.ContainsElements -- referencing any subtype of IfcProduct (with the
exception of other spatial structure element) by IfcRelContainedInSpatialStructure.RelatedElements.
Property Sets for Objects
The Property Sets for Objects concept applies to this entity as shown in Table 26.
Table 26 — IfcBuilding Property Sets for Objects
The Quantity Sets concept applies to this entity as shown in Table 27.
Table 27 — IfcBuilding Quantity Sets
The Product Placement concept applies to this entity.
The local placement for IfcBuilding 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 (if relative placement
is used) to the IfcSpatialStructureElement of type
IfcSite, or of type IfcBuilding (e.g. to
position a building relative to a building complex, or a
building section to a building).
- If the relative placement is not used, the absolute
placement is defined within the world coordinate system.
FootPrint GeomSet Geometry
The FootPrint GeomSet Geometry concept applies to this entity as shown in Table 28.
|FootPrint||GeometricCurveSet||IfcGeometricCurveSet||Set of curves (outer and inner) representing the floor projection,|
Table 28 — IfcBuilding FootPrint GeomSet Geometry
The foot print representation of IfcBuilding is given
by either a single 2D curve (such as IfcPolyline or
IfcCompositeCurve), or by a list of 2D curves (in case
of inner boundaries), if the building has an independent
NOTE The independent geometric representation of IfcBuilding may not be allowed in certain model view definitions. In those cases only the contained elements and spaces have an independent geometric representation.
The Body Geometry concept applies to this entity.
The body (or solid model) geometric representation (if the
building has an independent geometric representation) of
IfcBuilding is defined using faceted B-Rep
capabilities (with or without voids), based on the
IfcFacetedBrep or on the
NOTE Since the building shape is usually described by the
exterior building elements, an independent shape representation
shall only be given, if the building is exposed
independently from its constituting elements and such independent geometric representation may be prohibited in model view definitions.
XSD Specification: <xs:element name="IfcBuilding" type="ifc:IfcBuilding" substitutionGroup="ifc:IfcSpatialStructureElement" nillable="true"/>
<xs:element name="BuildingAddress" type="ifc:IfcPostalAddress" nillable="true" minOccurs="0"/>
<xs:attribute name="ElevationOfRefHeight" type="ifc:IfcLengthMeasure" use="optional"/>
<xs:attribute name="ElevationOfTerrain" type="ifc:IfcLengthMeasure" use="optional"/>
|ElevationOfRefHeight|| : ||Elevation above sea level of the reference height used for all storey elevation measures, equals to height 0.0. It is usually the ground floor level.|
|ElevationOfTerrain|| : ||Elevation above the minimal terrain level around the foot print of the building, given in elevation above sea level.|
|BuildingAddress|| : ||Address given to the building for postal purposes.|
Link to this page