Definition from IAI: Opening Element stands for opening, recess or chase, all reflecting voids. It represents a void within any element that has physical manifestation. Openings must be handled by all sectors and disciplines in AEC/FM industry, therefore the interoperability for opening elements is provided at this high level.
The quantities relating to the space 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 |
| OpeningArea | Area of the opening as viewed by an elevation view (for wall openings) or as viewed by a ground floor view (for floor openings). The exact definition and calculation rules depend on the method of measurement used. | IfcAreaQuantity |
HISTORY New entity in IFC Release 1.0
ISSUE See issue log for changes made in IFC Release 1.5.1. See issue and change log for changes made in IFC Release 2.x
Geometry Use Definitions:
The geometric representation of IfcOpeningElement is given by the IfcProductDefinitionShape and IfcLocalPlacement allowing multiple geometric representations.
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. refered to by VoidsElement.RelatingBuildingElement.
Standard Geometric Representation using Swept Solid Representation
The standard geometric representation of IfcOpeningElement is defined using the swept area solid geometry. The attribute RepresentationType of IfcShapeRepresentation should have the value 'SweptSolid'. The following additional constraints apply to the swept solid representation:
- Solid: IfcExtrudedAreaSolid is required.
- Profile: IfcRectangleProfileDef shall be supported.
- Extrusion: The profile shall be extruded horizontally (i.e. perpendicular to the extrusion direction of the voided element), e.g. for wall openings, or vertically (i.e. in the extrusion direction of the voided element), e.g., for floor openings.
Special agreement for defining openings in round building elements, e.g., in round walls. The opening width, in case of a rectangular opening equal with the IfcRectangleProfileDef.XDim, is defined as the straight line distance between two parallel jambs. If the jambs are defined radial (to the center of the arc used to define the round wall) then the opening width is defined to be the outer arc length.
NOTE: In case of non-parallel jambs, the geometry expression is not an extruded area solid, it has to be represented using other types of representations.
EXAMPLE
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The following interpretation of dimension parameter applies for rectangular openings:
NOTE: Rectangles are now defined centric, the placement location has to be set:
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Advanced Geometric Representation using Swept Solid Representation
The advanced geometric representation of IfcOpeningElement is defined using the swept area solid geometry. The following additional constraints apply to the swept solid representation:
- Solid: see standard geometric representation,
- Profile: IfcRectangleProfileDef, IfcCircleProfileDef and IfcArbitraryClosedProfileDef shall be supported.
- Extrusion: see standard geometric representation