IfcCurtainWall

IfcCurtainWall

Definition of IAI: Exterior wall of a building which is an assembly of components, hung from the edge of the floor/roof structure rather than bearing on a floor. Curtain wall is represented as an building element assembly and implemented as subtype of IfcBuildingElement that uses an IfcRelAggregates relationship.

HISTORY New Entity in IFC Release 2.0

Geometry Use Definitions

The geometric representation of IfcCurtainWall is given by the IfcProductDefinitionShape, allowing multiple geometric representation. Independent geometric representations, as described below, should only be used when the IfcCurtainWall is not defined as an aggregate. If defined as an aggregate, the geometric representation is the sum of the representations of the components within the aggregate.

Local placement

The local placement for IfcCurtainWall 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 given) to the same IfcSpatialStructureElement , which is used in the ContainedInStructure inverse attribute, or to a spatial structure element at a higher level, referenced by that.
If the relative placement is not used, the absolute placement is defined within the world coordinate system.

If the IfcCurtainWall establishes an aggregate, than all contained elements (defined by the IsDecomposedBy inverse attribute) shall be placed relative to the IfcCurtainWall.ObjectPlacement.

Geometric Representation

The BoundingBox, the SurfaceModel and the Brep geometric representation of IfcCurtainWall is defined at the supertype IfcBuildingElement.

EXPRESS specification:

ENTITY IfcCurtainWall

SUBTYPE OF (

IfcBuildingElement);

WHERE

WR61

(HIINDEX(SELF\IfcObject.IsDecomposedBy) = 0) OR ((HIINDEX(SELF\IfcObject.IsDecomposedBy) = 1) AND (EXISTS(SELF\IfcProduct.Representation)));

END_ENTITY;

Formal Propositions:

WR61

Either the curtain wall is not decomposed into its curtain wall elements (the curtain wall can have independent geometry), or the geometry shall not be given at IfcCurtainWall directly.

References (1):

Name

Type

Referred through

Express-G

IfcBuildingElement

Entity

Subtype

Diagram 1

Inheritance graph

ENTITY IfcCurtainWall;

ENTITY IfcRoot;

GlobalId

IfcGloballyUniqueId;

OwnerHistory

IfcOwnerHistory;

Name

OPTIONAL IfcLabel;

Description

OPTIONAL IfcText;

ENTITY IfcObject;

ObjectType

OPTIONAL IfcLabel;

INVERSE

IsDefinedBy

SET OF IfcRelDefines FOR RelatedObjects;

HasAssociations

SET OF IfcRelAssociates FOR RelatedObjects;

HasAssignments

SET OF IfcRelAssigns FOR RelatedObjects;

Decomposes

SET OF IfcRelDecomposes FOR RelatedObjects;

IsDecomposedBy

SET [0:1] OF IfcRelDecomposes FOR RelatingObject;

ENTITY IfcProduct;

ObjectPlacement

OPTIONAL IfcObjectPlacement;

Representation

OPTIONAL IfcProductRepresentation;

INVERSE

ReferencedBy

SET OF IfcRelAssignsToProduct FOR RelatingProduct;

ENTITY IfcElement;

Tag

OPTIONAL IfcIdentifier;

INVERSE

ConnectedTo

SET OF IfcRelConnectsElements FOR RelatingElement;

ConnectedFrom

SET OF IfcRelConnectsElements FOR RelatedElement;

ContainedInStructure

SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;

ENTITY IfcBuildingElement;

INVERSE

ProvidesBoundaries

SET OF IfcRelSpaceBoundary FOR RelatedBuildingElement;

HasOpenings

SET OF IfcRelVoidsElement FOR RelatingBuildingElement;

FillsVoids

SET OF IfcRelFillsElement FOR RelatedBuildingElement;

END_ENTITY;