#### 5.4.3.14 IfcOpeningElement

| Ouverture
| Öffnung

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. The relationship implies a Boolean subtraction operation between the volume of the voided element and the volume of the opening. It may be filled by an IfcDoor, IfcWindow, or another filling element by using the relationship IfcRelFillsElements.

> 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.

Containment Use Definition

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.

## Plumbing System Design

Openings are required for plumbing design to determine placement of fixtures and piping.

Instance diagram

Identity

The Identity concept applies to this entity.

Exchange |  |  |  |  |  |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Import |  |  |  |  |  |  |  |  |  |  |  |  |
Export |  |  |  |  |  |  |  | R |  |  | R | R | R

Placement

The Placement concept applies to this entity.

Opening locations must be known for layout of plumbing fixtures and piping.

Exchange |  |  |  |  |  |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Import |  |  |  |  |  |  |  |  |  |  |  |  |
Export |  |  |  |  |  |  |  | R |  |  | R | R | R

Body Geometry

The Body Geometry concept applies to this entity as shown in Table 19.

RepresentationType | Geometry
--- | ---
SweptSolid | IfcExtrudedAreaSolid
Brep | IfcFacetedBrep
Table 19 — IfcOpeningElement Body Geometry

Opening geometry must be known for layout of plumbing fixtures and piping.

Exchange |  |  |  |  |  |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Import |  |  |  |  |  |  |  |  |  |  |  |  |
Export |  |  |  |  |  |  |  | R |  |  | R | R | R

XSD Specification:

<xs:element name="IfcOpeningElement" type="ifc:IfcOpeningElement" substitutionGroup="ifc:IfcFeatureElementSubtraction" nillable="true"/>
<xs:complexType name="IfcOpeningElement">
<xs:complexContent>
<xs:extension base="ifc:IfcFeatureElementSubtraction"/>
</xs:complexContent>
</xs:complexType>

EXPRESS Specification:

ENTITY IfcOpeningElement

| SUPERTYPE OF(IfcOpeningStandardCase)

| SUBTYPE OF (IfcFeatureElementSubtraction);

PredefinedType | : | OPTIONAL IfcStrippedOptional;

| INVERSE

END_ENTITY;

Attribute Definitions:

Inheritance Graph:

ENTITY IfcOpeningElement

| ENTITY IfcRoot

GlobalId | : | IfcGloballyUniqueId;
OwnerHistory | : | OPTIONAL IfcOwnerHistory;
Name | : | OPTIONAL IfcLabel;
Description | : | OPTIONAL IfcText;

| ENTITY IfcObjectDefinition

| INVERSE

HasAssignments | : | SET OF IfcRelAssigns FOR RelatedObjects;
Nests | : | SET [0:1] OF IfcRelNests FOR RelatedObjects;
IsNestedBy | : | SET OF IfcRelNests FOR RelatingObject;
HasContext | : | SET [0:1] OF IfcRelDeclares FOR RelatedDefinitions;
IsDecomposedBy | : | SET OF IfcRelAggregates FOR RelatingObject;
Decomposes | : | SET [0:1] OF IfcRelAggregates FOR RelatedObjects;
HasAssociations | : | SET OF IfcRelAssociates FOR RelatedObjects;

| ENTITY IfcObject

ObjectType | : | OPTIONAL IfcStrippedOptional;

| INVERSE

IsDeclaredBy | : | SET [0:1] OF IfcRelDefinesByObject FOR RelatedObjects;
Declares | : | SET OF IfcRelDefinesByObject FOR RelatingObject;
IsTypedBy | : | SET [0:1] OF IfcRelDefinesByType FOR RelatedObjects;
IsDefinedBy | : | SET OF IfcRelDefinesByProperties FOR RelatedObjects;

| ENTITY IfcProduct

ObjectPlacement | : | OPTIONAL IfcObjectPlacement;
Representation | : | OPTIONAL IfcProductRepresentation;

| INVERSE

ReferencedBy | : | SET OF IfcRelAssignsToProduct FOR RelatingProduct;

| ENTITY IfcElement

Tag | : | OPTIONAL IfcStrippedOptional;

| INVERSE

ConnectedTo | : | SET OF IfcRelConnectsElements FOR RelatingElement;
IsInterferedByElements | : | SET OF IfcRelInterferesElements FOR RelatedElement;
InterferesElements | : | SET OF IfcRelInterferesElements FOR RelatingElement;
HasOpenings | : | SET OF IfcRelVoidsElement FOR RelatingBuildingElement;
ProvidesBoundaries | : | SET OF IfcRelSpaceBoundary FOR RelatedBuildingElement;
ConnectedFrom | : | SET OF IfcRelConnectsElements FOR RelatedElement;
ContainedInStructure | : | SET [0:1] OF IfcRelContainedInSpatialStructure FOR RelatedElements;

| ENTITY IfcFeatureElement

| ENTITY IfcFeatureElementSubtraction

| INVERSE

VoidsElements | : | IfcRelVoidsElement FOR RelatedOpeningElement;

| ENTITY IfcOpeningElement

PredefinedType | : | OPTIONAL IfcStrippedOptional;

| INVERSE

END_ENTITY;

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