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ELEMENT PROPERTIES AND
QUANTITIES OF IFC4
EXTRACTION OF EXISTING PROPERTYSET (PSET) AND
QUANTITYSET (QTO) DEFINITIONS FROM IFC4 SPECS
Report of IFC Psets and Qsets
1 von 4
Cuneco
Report of IFC Psets and Qsets
1.1
Aim
Definitions of the IFC4 standard shall be extracted from available Pset and Qto specifications and shall be
stored in an Excel sheet. This Excel sheet shall help to make a gap analysis, i.e. to identify data that is not
yet able to be stored in an IFC4 data model.
1.2
IFC4 specifications
The following data sources have been used for data extraction:
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all Pset definitions of IFC4 (available as XML files, according to PSD_IFC4.xsd)
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all Qto definition of IFC4 (available as XML files, according to QTO_IFC4.xsd)
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IFC4 schema definition (available as EXPRESS specification)
1.3
Result
Properties and quantities are defined for BIM elements, but not all BIM elements are relevant for this study.
Therefore, a filter has been defined that selects all relevant BIM elements. For IFC it means to choose all
1
2
non-abstract (instantiable) IFC entities being either a subtype of IfcElement or IfcSpatialStructureElement .
For those elements all properties and quantities have been extracted from the Pset and Qto files and have
been exported to a single Excel file. Each BIM element is stored in an own sheet and provides the following
data:
-
Name of the property
-
Name of the property group (each property is part of a property group)
-
Description
-
Data type
-
Unit type (if provided)
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IFC Path (hidden column E)
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IFD GUID (if provided, hidden column F)
An example of the beam element (IfcBeam) is shown in the screenshot below.
The applicability of property and quantity sets to the individual IFC elements are defined within the property
set definitions, by “ApplicableClass” – the report resolves all these dependencies and also the dependencies
introduced by the IFC schema using sub typing.
As an example: the Pset_ManufacturerTypeInformation has the “ApplicableClass” being IfcElement,
therefore it is added to all tabs, representing the BIM elements being subtypes of IfcElement.
Please note that “ElementedCase” and “StandardCase” elements like IfcWallElementedCase or
IfcBeamStandardCase have been filtered out from export as they do not add additional properties to their
super type IfcWall or IfcBeam.
1
http://www.buildingsmart-tech.org/ifc/IFC4/final/html/schema/ifcproductextension/lexical/ifcelement.htm
2
http://www.buildingsmart-tech.org/ifc/IFC4/final/html/schema/ifcproductextension/lexical/ifcspatialstructureelement.htm
Matthias Weise
Element properties and quantities of IFC4
page 2 of 4
Cuneco
Report of IFC Psets and Qsets
BIM element
Figure 1: Report of properties and base quantities defined in IFC4 for each BIM element
1.4
Out of Scope
Besides the dynamic link to properties and quantities, stored as XML definitions linked to the IFC elements,
the IFC specification provides additional information defined by the schema (direct attributes or references to
other classes).
Those IFC Schema definitions are used to store information like:
-
-
By direct attributes
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Identification
-
Name
-
Description
-
Tag
-
Object type (selectable from a predefined list, or generic user defined type)
By link to other classes within the IFC schema
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Classification
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Link to external libraries
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Link to external documentations (such as pdf and other files)
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External to other external references
Matthias Weise
Element properties and quantities of IFC4
page 3 of 4
Cuneco
Report of IFC Psets and Qsets
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Material information, including also material properties
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Owner history (revision control)
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Assignment to tasks and processes
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Cost items
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Aggregation of subordinate parts
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Features (e.g. openings in a building element)
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Placement (logically within a building structure, and geometrically)
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Connectivity
-
Constraints
-
Approvals
-
…
This kind of information is not part of the generated Excel sheets. The currently developed report for the
Cuneco project only allows interpreting the IFC schema and the external Pset and Qset XML definitions.
In order to have a complete report of all alphanumerical information on BIM elements being specified in the
international IFC standard these additional information items need to be extracted from the IFC schema
interpreting the mvdXML definitions for those information groups (also called “concepts”). This would require
a feasible extension of the reporting functions.
Matthias Weise
Element properties and quantities of IFC4
page 4 of 4