IfcOpeningElement

Semantic definitions at the entity

Entity definition

The opening element stands for opening, recess or chase, all reflecting voids. It represents a void within any element that has physical manifestation. Openings can be inserted into walls, slabs, beams, columns, or other elements.

The IFC specification provides two entities for opening elements:

IfcOpeningStandardCase is used for all openings that have a constant profile along a linear extrusion. They are placed relative to the voided elements and the extrusion direction is perpendicular to the plane of the element (horizontally for walls, vertically for slabs). Only a single extrusion body is allowed. It cuts through the whole thickness of the voided element, i.e. it reflects a true opening.
IfcOpeningElement is used for all other occurrences of openings and in particular also for niches or recesses.

NOTE View definitions or implementer agreements may restrict the types of elements which can be voided by an IfcOpeningElement or IfcOpeningStandardCase

There are two different types of opening elements:

an opening, where the thickness of the opening is greater or equal to the thickness of the element;
a recess or niche, where the thickness of the recess is smaller than the thickness of the element.

The attribute PredefinedType should be used to capture the differences,

the attribute is set to OPENING for an opening or
the attribute is set to RECESS for a recess or niche.
If the value for PredefinedType is omitted, or the value is set to NOTDEFINED, no specific information of whether it is an opening or recess shall be assumed.

An IfcOpeningElement has to be inserted into an IfcElement by using the IfcRelVoidsElement relationship. It may be filled by an IfcDoor, IfcWindow, or another filling element by using the relationship IfcRelFillsElements. Depending on the type of the IfcShapeRepresentation of the IfcOpeningElement the voiding relationship implies:

if the IfcShapeRepresentation.<emRepresentationIdentifier = 'Body', then the Body shape represntation of the opening has to be subtracted from the body shape representation of the voided element - implicit Boolean difference operation.
if the IfcShapeRepresentation.<emRepresentationIdentifier = 'Reference', then the Reference shape representation of the opening is not subtracted, it is provided in addition to the hole in the Body shape representation of the voided element.

The IfcOpeningElement shall not participate in the containment relationship, i.e. it is not linked directly to the spatial structure of the project. It has a mandatory VoidsElements inverse relationship pointing to the IfcElement that is contained in the spatial structure.

The inverse relationship ContainedInStructure shall be NIL.

NOTE See IfcRelVoidsElement for a diagram on how to apply spatial containment and the voiding relationship.

HISTORY New entity in IFC1.0

IFC2x CHANGE The intermediate ABSTRACT supertypes IfcFeatureElement and IfcFeatureSubtraction have been added.

IFC4 CHANGE The attribute PredefinedType has been added at the end of attribute list. It should be used instead of the inherited attribute ObjectType from now on.

Attribute definitions

#	Attribute	Type	Cardinality	Description	G
9	PredefinedType	IfcOpeningElementTypeEnum	?	Predefined generic type for an opening that is specified in an enumeration. There may be a property set given specificly for the predefined types. IFC4 CHANGE The attribute has been added at the end of the entity definition.	X
	HasFillings	IfcRelFillsElement @RelatingOpeningElement	S[0:?]	Reference to the Filling Relationship that is used to assign Elements as Fillings for this Opening Element. The Opening Element can be filled with zero-to-many Elements.	X

Inherited definitions from supertypes

Entity inheritance

Attribute inheritance

#	Attribute	Type	Cardinality	Description	G
IfcRoot
1	GlobalId	IfcGloballyUniqueId		Assignment of a globally unique identifier within the entire software world.	X
2	OwnerHistory	IfcOwnerHistory	?	Assignment of the information about the current ownership of that object, including owning actor, application, local identification and information captured about the recent changes of the object, NOTE only the last modification in stored - either as addition, deletion or modification. IFC4 CHANGE The attribute has been changed to be OPTIONAL.	X
3	Name	IfcLabel	?	Optional name for use by the participating software systems or users. For some subtypes of IfcRoot the insertion of the Name attribute may be required. This would be enforced by a where rule.	X
4	Description	IfcText	?	Optional description, provided for exchanging informative comments.	X
IfcObjectDefinition
	HasAssignments	IfcRelAssigns @RelatedObjects	S[0:?]	Reference to the relationship objects, that assign (by an association relationship) other subtypes of IfcObject to this object instance. Examples are the association to products, processes, controls, resources or groups.	X
	Nests	IfcRelNests @RelatedObjects	S[0:1]	References to the decomposition relationship being a nesting. It determines that this object definition is a part within an ordered whole/part decomposition relationship. An object occurrence or type can only be part of a single decomposition (to allow hierarchical strutures only). IFC4 CHANGE The inverse attribute datatype has been added and separated from Decomposes defined at IfcObjectDefinition.	X
	IsNestedBy	IfcRelNests @RelatingObject	S[0:?]	References to the decomposition relationship being a nesting. It determines that this object definition is the whole within an ordered whole/part decomposition relationship. An object or object type can be nested by several other objects (occurrences or types). IFC4 CHANGE The inverse attribute datatype has been added and separated from IsDecomposedBy defined at IfcObjectDefinition.	X
	HasContext	IfcRelDeclares @RelatedDefinitions	S[0:1]	References to the context providing context information such as project unit or representation context. It should only be asserted for the uppermost non-spatial object. IFC4 CHANGE The inverse attribute datatype has been added.	X
	IsDecomposedBy	IfcRelAggregates @RelatingObject	S[0:?]	References to the decomposition relationship being an aggregation. It determines that this object definition is whole within an unordered whole/part decomposition relationship. An object definitions can be aggregated by several other objects (occurrences or parts). IFC4 CHANGE The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.	X
	Decomposes	IfcRelAggregates @RelatedObjects	S[0:1]	References to the decomposition relationship being an aggregation. It determines that this object definition is a part within an unordered whole/part decomposition relationship. An object definitions can only be part of a single decomposition (to allow hierarchical strutures only). IFC4 CHANGE The inverse attribute datatype has been changed from the supertype IfcRelDecomposes to subtype IfcRelAggregates.	X
	HasAssociations	IfcRelAssociates @RelatedObjects	S[0:?]	Reference to the relationship objects, that associates external references or other resource definitions to the object.. Examples are the association to library, documentation or classification.	X
IfcObject
5	ObjectType	IfcLabel	?	The type denotes a particular type that indicates the object further. The use has to be established at the level of instantiable subtypes. In particular it holds the user defined type, if the enumeration of the attribute PredefinedType is set to USERDEFINED.	X
	IsDeclaredBy	IfcRelDefinesByObject @RelatedObjects	S[0:1]	Link to the relationship object pointing to the declaring object that provides the object definitions for this object occurrence. The declaring object has to be part of an object type decomposition. The associated IfcObject, or its subtypes, contains the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes. IFC4 CHANGE New inverse relationship, change made with upward compatibility for file based exchange.	X
	Declares	IfcRelDefinesByObject @RelatingObject	S[0:?]	Link to the relationship object pointing to the reflected object(s) that receives the object definitions. The reflected object has to be part of an object occurrence decomposition. The associated IfcObject, or its subtypes, provides the specific information (as part of a type, or style, definition), that is common to all reflected instances of the declaring IfcObject, or its subtypes. IFC4 CHANGE New inverse relationship, change made with upward compatibility for file based exchange.	X
	IsTypedBy	IfcRelDefinesByType @RelatedObjects	S[0:1]	Set of relationships to the object type that provides the type definitions for this object occurrence. The then associated IfcTypeObject, or its subtypes, contains the specific information (or type, or style), that is common to all instances of IfcObject, or its subtypes, referring to the same type. IFC4 CHANGE New inverse relationship, the link to IfcRelDefinesByType had previously be included in the inverse relationship IfcRelDefines. Change made with upward compatibility for file based exchange.	X
	IsDefinedBy	IfcRelDefinesByProperties @RelatedObjects	S[0:?]	Set of relationships to property set definitions attached to this object. Those statically or dynamically defined properties contain alphanumeric information content that further defines the object. IFC4 CHANGE The data type has been changed from IfcRelDefines to IfcRelDefinesByProperties with upward compatibility for file based exchange.	X
IfcProduct
6	ObjectPlacement	IfcObjectPlacement	?	Placement of the product in space, the placement can either be absolute (relative to the world coordinate system), relative (relative to the object placement of another product), or constraint (e.g. relative to grid axes). It is determined by the various subtypes of IfcObjectPlacement, which includes the axis placement information to determine the transformation for the object coordinate system.	X
7	Representation	IfcProductRepresentation	?	Reference to the representations of the product, being either a representation (IfcProductRepresentation) or as a special case a shape representations (IfcProductDefinitionShape). The product definition shape provides for multiple geometric representations of the shape property of the object within the same object coordinate system, defined by the object placement.	X
	ReferencedBy	IfcRelAssignsToProduct @RelatingProduct	S[0:?]	Reference to the IfcRelAssignsToProduct relationship, by which other products, processes, controls, resources or actors (as subtypes of IfcObjectDefinition) can be related to this product.	X
	PositionedRelativeTo	IfcRelPositions @RelatedProducts	S[0:1]		X
	ReferencedInStructures	IfcRelReferencedInSpatialStructure @RelatedElements	S[0:?]		X
IfcElement
8	Tag	IfcIdentifier	?	The tag (or label) identifier at the particular instance of a product, e.g. the serial number, or the position number. It is the identifier at the occurrence level.	X
	FillsVoids	IfcRelFillsElement @RelatedBuildingElement	S[0:1]	Reference to the IfcRelFillsElement Relationship that puts the element as a filling into the opening created within another element.	X
	ConnectedTo	IfcRelConnectsElements @RelatingElement	S[0:?]	Reference to the element connection relationship. The relationship then refers to the other element to which this element is connected to.	X
	IsInterferedByElements	IfcRelInterferesElements @RelatedElement	S[0:?]	Reference to the interference relationship to indicate the element that is interfered. The relationship, if provided, indicates that this element has an interference with one or many other elements. NOTE There is no indication of precedence between IsInterferedByElements and InterferesElements. IFC4 CHANGE New inverse relationship.	X
	InterferesElements	IfcRelInterferesElements @RelatingElement	S[0:?]	Reference to the interference relationship to indicate the element that interferes. The relationship, if provided, indicates that this element has an interference with one or many other elements. NOTE There is no indication of precedence between IsInterferedByElements and InterferesElements. IFC4 CHANGE New inverse relationship.	X
	HasProjections	IfcRelProjectsElement @RelatingElement	S[0:?]	Projection relationship that adds a feature (using a Boolean union) to the IfcBuildingElement.	X
	HasOpenings	IfcRelVoidsElement @RelatingBuildingElement	S[0:?]	Reference to the IfcRelVoidsElement relationship that creates an opening in an element. An element can incorporate zero-to-many openings. For each opening, that voids the element, a new relationship IfcRelVoidsElement is generated.	X
	IsConnectionRealization	IfcRelConnectsWithRealizingElements @RealizingElements	S[0:?]	Reference to the connection relationship with realizing element. The relationship, if provided, assigns this element as the realizing element to the connection, which provides the physical manifestation of the connection relationship.	X
	ProvidesBoundaries	IfcRelSpaceBoundary @RelatedBuildingElement	S[0:?]	Reference to space boundaries by virtue of the objectified relationship IfcRelSpaceBoundary. It defines the concept of an element bounding spaces.	X
	ConnectedFrom	IfcRelConnectsElements @RelatedElement	S[0:?]	Reference to the element connection relationship. The relationship then refers to the other element that is connected to this element.	X
	ContainedInStructure	IfcRelContainedInSpatialStructure @RelatedElements	S[0:1]	Containment relationship to the spatial structure element, to which the element is primarily associated. This containment relationship has to be hierachical, i.e. an element may only be assigned directly to zero or one spatial structure.	X
	HasCoverings	IfcRelCoversBldgElements @RelatingBuildingElement	S[0:?]	Reference to IfcCovering by virtue of the objectified relationship IfcRelCoversBldgElement. It defines the concept of an element having coverings associated.	X
IfcFeatureElement
IfcFeatureElementSubtraction
	VoidsElements	IfcRelVoidsElement @RelatedOpeningElement		Reference to the Voids Relationship that uses this Opening Element to create a void within an Element. The Opening Element can only be used to create a single void within a single Element.	X
IfcOpeningElement
9	PredefinedType	IfcOpeningElementTypeEnum	?	Predefined generic type for an opening that is specified in an enumeration. There may be a property set given specificly for the predefined types. IFC4 CHANGE The attribute has been added at the end of the entity definition.	X
	HasFillings	IfcRelFillsElement @RelatingOpeningElement	S[0:?]	Reference to the Filling Relationship that is used to assign Elements as Fillings for this Opening Element. The Opening Element can be filled with zero-to-many Elements.	X

Definitions applying to General Usage

Instance diagram

Concept usage

Property Sets for Objects

The Property Sets for Objects concept template applies to this entity as shown in Table 67.

PsetName

Properties

Pset_OpeningElementCommon

Template	PropertyName	Value	Reference
Single Value	Reference	IfcIdentifier
Enumerated Value	Status	IfcLabel	PEnum_ElementStatus
Single Value	Purpose	IfcLabel
Single Value	FireExit	IfcBoolean
Single Value	ProtectedOpening	IfcBoolean

Table 67 — IfcOpeningElement Property Sets for Objects

Quantity Sets

The Quantity Sets concept template applies to this entity as shown in Table 68.

QsetName

Quantities

Qto_OpeningElementBaseQuantities

Template	QuantityName	LengthValue	AreaValue	VolumeValue
Length Quantity	Width
Length Quantity	Height
Length Quantity	Depth
Area Quantity	Area
Volume Quantity	Volume

Table 68 — IfcOpeningElement Quantity Sets

Product Local Placement

The Product Local Placement concept template applies to this entity as shown in Table 69.

Table 69 — IfcOpeningElement Product Local Placement

The local placement for IfcOpeningElement 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 should point to the local placement of the same element, which is voided by the opening, i.e. referred to by VoidsElement.RelatingBuildingElement.

Body Geometry

The Body Geometry concept applies to this entity.

The 'Body' representation of IfcOpeningElement can be represented using the representation types 'SweptSolid', and 'Brep'. The representation type 'Brep' is explained at IfcFeatureElement

Swept Solid Representation Type with Horizontal Extrusion

The 'SweptSolid' geometric representation of IfcOpeningElement, using horizontal extrusion direction (for walls), is defined using the swept area solid geometry. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

RepresentationIdentifier : 'Body'
RepresentationType : 'SweptSolid'

The following additional constraints apply to the swept solid representation:

Solid: IfcExtrudedAreaSolid is required, the set of IfcShapeRepresentation.Items may include a single, or multiple, instances of IfcExtrudedAreaSolid.
Profile: IfcRectangleProfileDef, IfcCircleProfileDef and IfcArbitraryClosedProfileDef shall be supported.
Extrusion: The profile shall be extruded horizontally (perpendicular to the extrusion direction of the voided element such as for wall openings), or vertically (in the extrusion direction of the voided element such as for for floor openings). If multiple instances of IfcExtrudedAreaSolid are used, the extrusion direction of each extrusion should be equal.

NOTE In case of non-parallel jambs, the shape representation shall be a 'SweptSolid' representation with vertical extrusion.

Figure 158 illustrates an opening with horizontal extrusion.

NOTE The local placement directions for the IfcOpeningElement are only given as an example, other directions are valid as well.

Figure 158 — Opening with full extrusion

Figure 159 illustrates an opening for a recess.

NOTE The local placement directions for the IfcOpeningElement are only given as an example, other directions are valid as well.

NOTE Rectangles are now defined centric, the placement location has to be set:

IfcCartesianPoint(XDim/2,YDim/2)

Figure 159 — Opening with recess extrusion

Swept Solid Representation with Vertical Extrusion

The 'SweptSolid' geometric representation of IfcOpeningElement, using vertical extrusion direction (for walls), is defined using the swept area solid geometry, however the extrusion direction may be vertical, i.e. in case of a wall opening, the extrusion would be in the direction of the wall height. The following attribute values for the IfcShapeRepresentation holding this geometric representation shall be used:

RepresentationIdentifier : 'Body'
RepresentationType : 'SweptSolid'

The following additional constraints apply to the swept solid representation:

Solid: IfcExtrudedAreaSolid is required, the set of IfcShapeRepresentation.Items may include a single, or multiple, instances of IfcExtrudedAreaSolid.
Profile: IfcRectangleProfileDef, IfcCircleProfileDef and IfcArbitraryClosedProfileDef shall be supported.
Extrusion: The profile shall be extruded vertically, i.e. for wall openings along the extrusion direction of the voided element. If multiple instances of IfcExtrudedAreaSolid are used, the extrusion direction should be equal.

Vertical extrusions shall be used when an opening or recess has a non rectangular foot print geometry that does not change along the height of the opening or recess.

Figure 160 shows a vertical extrusion with multiple extrusion bodies for the opening. Each extrusion body has a different extrusion lenght.

NOTE The local placement directions for the IfcOpeningElement are only given as an example, other directions are valid as well.

Figure 160 — Opening with multiple extrusions

Reference Geometry

The Reference Geometry concept applies to this entity.

Since there are no Boolean operations, either as IfcBooleanResult or implicitly by IfcRelVoidsElement the geometry of the IfcOpeningElement shall not be used to subtract the opening from the 'Body' shape representation of the voided element.

mvdXML Specification


<?xml version="1.0" encoding="utf-8"?>

<ConceptRoot xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" uuid="2b58c57e-3ac1-4d90-b3f0-ac2daac69ed7" name="IfcOpeningElement" applicableRootEntity="IfcOpeningElement">

 <Applicability>

  <Template ref="aead99d1-e4e5-487d-948c-3780dd5079a2" />

  <TemplateRules operator="and">

  </TemplateRules>

 </Applicability>

 <Concepts>

  <Concept uuid="84c422e2-81be-487f-986c-a528195940c9" name="Property Sets for Objects" override="true">

   <Template ref="f74255a6-0c0e-4f31-84ad-24981db62461" />

   <TemplateRules operator="and">

    <TemplateRule Parameters="PsetName[Value]=&apos;Pset_OpeningElementCommon&apos;" />

   </TemplateRules>

  </Concept>

  <Concept uuid="cb4e8bac-821e-44e8-9d22-e77b021736b1" name="Quantity Sets">

   <Template ref="6652398e-6579-4460-8cb4-26295acfacc7" />

   <TemplateRules operator="and">

    <TemplateRule Parameters="QsetName[Value]=&apos;Qto_OpeningElementBaseQuantities&apos;" />

   </TemplateRules>

  </Concept>

  <Concept uuid="c3fa5292-4e42-44fa-ba31-e6444ae13ed0" name="Product Local Placement">

   <Template ref="cbe85b5f-7912-4a43-8bb7-1e63bf40b26d" />

  </Concept>

  <Concept uuid="f55ff4eb-9d4d-4329-9c16-3b7f60901a2b" name="Body Geometry">

   <Template ref="c446bd16-2de3-4b97-b34f-4446ac0badc2" />

  </Concept>

  <Concept uuid="c84c3c3f-8873-4653-a768-9b4f85380634" name="Reference Geometry">

   <Template ref="d68f9f1b-223a-4a8a-912b-b83f032a74f2" />

  </Concept>

 </Concepts>

</ConceptRoot>

Concept inheritance

#	Concept	Template	Model View
IfcRoot
	Identity	Software Identity	General Usage
	Revision Control	Revision Control	General Usage
IfcObjectDefinition
	Classification Association	Classification Association	General Usage
IfcObject
	Object User Identity	Object User Identity	General Usage
	Object Predefined Type	Object Predefined Type	General Usage
	Object Typing	Object Typing	General Usage
	Property Sets with Override	Property Sets with Override	General Usage
IfcProduct
	Product Placement	Product Placement	General Usage
	Product Geometric Representation	Product Geometric Representation	General Usage
IfcElement
	CoG Geometry	CoG Geometry	General Usage
	Box Geometry	Box Geometry	General Usage
	FootPrint Geometry	FootPrint Geometry	General Usage
	Body SurfaceOrSolidModel Geometry	Body SurfaceOrSolidModel Geometry	General Usage
	Body SurfaceModel Geometry	Body SurfaceModel Geometry	General Usage
	Body Tessellation Geometry	Body Tessellation Geometry	General Usage
	Body Brep Geometry	Body Brep Geometry	General Usage
	Body AdvancedBrep Geometry	Body AdvancedBrep Geometry	General Usage
	Body CSG Geometry	Body CSG Geometry	General Usage
	Mapped Geometry	Mapped Geometry	General Usage
	Element Voiding	Element Voiding	General Usage
	Element Projecting	Element Projecting	General Usage
	Linear Placement	Product Linear Placement	General Usage
IfcFeatureElement
	Spatial Containment	Spatial Containment	General Usage
IfcOpeningElement
	Property Sets for Objects	Property Sets for Objects	General Usage
	Quantity Sets	Quantity Sets	General Usage
	Product Local Placement	Product Local Placement	General Usage
	Body Geometry	Body Geometry	General Usage
	Reference Geometry	Reference Geometry	General Usage

Item	Change	Description
IFC2x3 to IFC4 4.0.0.0
IfcOpeningElement
OwnerHistory	MODIFIED	Instantiation changed to OPTIONAL.
PredefinedType	ADDED
IFC4 Addendum 1 4.0.1.0
IfcOpeningElement
HasCoverings	ADDED
IFC4x2 Candidate 4.2.0.0
IfcOpeningElement
PositionedRelativeTo	ADDED
IFC2x3 to IFC4 4.0.0.0
IfcOpeningElement
OwnerHistory	MODIFIED	Instantiation changed to OPTIONAL.
PredefinedType	ADDED
IFC4 Addendum 1 4.0.1.0
IfcOpeningElement
HasCoverings	ADDED
IFC4x2 Candidate 4.2.0.0
IfcOpeningElement
PositionedRelativeTo	ADDED

	Öffnung
	Opening Element
	Ouverture

IfcOpeningElement

Semantic definitions at the entity

Inherited definitions from supertypes

Definitions applying to General Usage

Formal representations