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IFC Overview summary

HVAC model 3


IFC Standard

Industry Foundation Classes (IFC) are the open and neutral data format for openBIM.

Quick links for developers:

IFC Specification Package

The IFC specification is developed and maintained by buildingSMART International as its "Data standard". Since IFC4 it is accepted as ISO 16739 standard.  The specification of the IFC standard includes for each major and minor edition:

  • the IFC Specification html documentation (including all definitions, schemas, libraries)
  • the URL for the IFC EXPRESS long form schema
  • the URL for the ifcXML XSD schema

For a comparison between the IFC EXPRESS and XSD publication, see here.


IFC Data File Formats and Icons

IFC data files are exchanged between applications using the following formats and should be indicated by the published icons:

.ifc IFC data file using the STEP physical file structure according to ISO10303-21. The *.ifc file shall validate according to the IFC-EXPRESS specification.

This is the default IFC exchange format.
.ifcXML IFC data file using the XML document structure. It can be generated directly by the sending application, or from an IFC data file using the conversion following ISO10303-28, the XML representation of EXPRESS schemas and data.

Note: an .ifcXML file is normally 300-400% larger then an .ifc file.
.ifcZIP IFC data file using the PKzip 2.04g compression algorithm (compatible with e.g. Windows compressed folders, winzip, zlib, info-zip, etc.). It requires to have a single .ifc or *.ifcXML data file in the main directory of the zip archive.

Note: an .ifcZIP files usually compress an .ifc down by 60-80% and an .ifcXML file by 90-95%.


Icons for IFC files for use in Windows and MACoperation systems


*) provided "as is" and without any warranty expressed or implied.


For more information see also: