IfcBuildingStorey

Definition from IAI: The building storey has an elevation and typically represents a (nearly) horizontal aggregation of spaces that are vertically bound.

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

COMPLEX = building storey complex
ELEMENT = building storey
PARTIAL = partial building storey

EXAMPLE: In split level houses, a storey is splitted into two or more partial storeys, each with a different elevation. It can be handled by defining a storey, which includes two or more partial storeys with the individual elevations.

HISTORY New entity in IFC Release 1.0

Property Set Use Definition

The property sets relating to the IfcBuildingStorey 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 IfcBuildingStorey are part of this IFC release:

Pset_BuildingStoreyCommon: common property set for all types of building stories

Quantity Use Definition

The quantities relating to the building storey 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
TotalHeight	Calculated height of this storey, from the bottom surface of the floor, to the bottom surface of the floor or roof above.	IfcQuantityLength
GrossFloorArea	Calculated sum of all areas covered by the building storey (as horizontal projections and normally including the area of construction elements). The exact definition and calculation rules depend on the method of measurement used.	IfcQuantityArea
NetFloorArea	Calculated sum of all usable areas covered by the building storey (normally excluding the area of construction elements). The exact definition and calculation rules depend on the method of measurement used.	IfcQuantityArea
GrossVolume	Calculated gross volume of all areas enclosed by the building storey (normally including the area of construction elements). The exact definition and calculation rules depend on the method of measurement used.	IfcQuantityVolume
NetVolume	Calculated net volume of all areas enclosed by the building storey (normally excluding the area of construction elements). The exact definition and calculation rules depend on the method of measurement used.	IfcQuantityVolume

Spatial Structure Use Definition

The IfcBuildingStorey 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 IfcBuildingStoreyreferences them by its inverse relationships:

IfcBuildingStorey.Decomposes -- referencing (IfcBuilding || IfcBuildingStorey) by IfcRelAggregates.RelatingObject, If it refers to another instance of IfcBuildingStorey, the referenced IfcBuildingStorey needs to have a different and higher CompositionType, i.e. COMPLEX (if the other IfcBuildingStorey has ELEMENT), or ELEMENT (if the other IfcBuildingStorey has PARTIAL).
IfcBuildingStorey.IsDecomposedBy -- referencing (IfcBuildingStorey || IfcSpace) by IfcRelAggregates.RelatedObjects. If it refers to another instance of IfcBuildingStorey, the referenced IfcBuildingStorey needs to have a different and lower CompositionType, i.e. ELEMENT (if the other IfcBuildingStorey has COMPLEX), or PARTIAL (if the other IfcBuildingStorey has ELEMENT).

If there are building elements and/or other elements directly related to the IfcBuildingStorey (like most building elements, such as walls, columns, etc.), they are associated with the IfcBuildingStorey by using the objectified relationship IfcRelContainedInSpatialStructure. The IfcBuildingStorey references them by its inverse relationship:

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

Geometry Use Definitions

The geometric representation of IfcBuildingStorey is given by the IfcProductDefinitionShape and IfcLocalPlacement, allowing multiple geometric representation.

Local Placement

The local placement for IfcBuildingStorey 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 "IfcBuilding", or of type "IfcBuildingStorey" (e.g. to position a building storey relative to a building storey complex, or a partial building storey to a building storey).
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 'GeometricCurveSet' and a 3D 'Body' representation of type 'Brep' is supported.

Foot Print Representation

The foot print representation of IfcBuildingStorey 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 storey has an independent geometric representation.

The representation identifier and type of this geometric representation of IfcBuildingStorey is:

IfcShapeRepresentation.RepresentationIdentifier = 'FootPrint'
IfcShapeRepresentation.RepresentationType = 'GeometricCurveSet'

Body Representation

The body (or solid model) geometric representation (if the building storey has an independent geometric representation) of IfcBuildingStorey is defined using faceted B-Rep capabilities (with or without voids), based on the IfcFacetedBrep or on the IfcFacetedBrepWithVoids.

The representation identifier and type of this representation of IfcBuildingStorey is:

IfcShapeRepresentation.RepresentationIdentifier = 'Body'
IfcShapeRepresentation.RepresentationType = 'Brep'

Since the building storey shape is usually described by the exterior building elements, an independent shape representation shall only be given, if the building storey is exposed independently from its constituting elements.

EXPRESS specification:

ENTITY IfcBuildingStorey

SUBTYPE OF (

IfcSpatialStructureElement);

Elevation

OPTIONAL IfcLengthMeasure;

END_ENTITY;

Attribute definitions:

Elevation

Elevation of the base of this storey, relative to the 0,00 internal reference height of the building. The 0.00 level is given by the absolute above sea level height by the ElevationOfRefHeight attribute given at IfcBuilding.

Inheritance graph

ENTITY IfcBuildingStorey;

ENTITY IfcRoot;

GlobalId

IfcGloballyUniqueId;

OwnerHistory

IfcOwnerHistory;

Name

OPTIONAL IfcLabel;

Description

OPTIONAL IfcText;

ENTITY IfcObjectDefinition;

INVERSE

HasAssignments

SET OF IfcRelAssigns FOR RelatedObjects;

IsDecomposedBy

SET OF IfcRelDecomposes FOR RelatingObject;

Decomposes

SET [0:1] OF IfcRelDecomposes FOR RelatedObjects;

HasAssociations

SET OF IfcRelAssociates FOR RelatedObjects;

ENTITY IfcObject;

ObjectType

OPTIONAL IfcLabel;

INVERSE

IsDefinedBy

SET OF IfcRelDefines FOR RelatedObjects;

ENTITY IfcProduct;

ObjectPlacement

OPTIONAL IfcObjectPlacement;

Representation

OPTIONAL IfcProductRepresentation;

INVERSE

ReferencedBy

SET OF IfcRelAssignsToProduct FOR RelatingProduct;

ENTITY IfcSpatialStructureElement;

LongName

OPTIONAL IfcLabel;

CompositionType

IfcElementCompositionEnum;

INVERSE

ReferencesElements

SET OF IfcRelReferencedInSpatialStructure FOR RelatingStructure;

ServicedBySystems

SET OF IfcRelServicesBuildings FOR RelatedBuildings;

ContainsElements

SET OF IfcRelContainedInSpatialStructure FOR RelatingStructure;

ENTITY IfcBuildingStorey;

Elevation

OPTIONAL IfcLengthMeasure;

END_ENTITY;