What is IFC?
Properties
IFC or Industry Foundation Classes is the best known and internationally leading standard for Open BIM data exchange. The vendor-neutral, open file format supports the interoperability of individual applications in the construction industry. IFC can be understood as a schema or specification that provides general information to capture all BIM information throughout the lifecycle of a building. It is an up-to-date copy of the original building model and is used, for example, for viewing, creating simulations, cost estimates or collision checks, archiving and referencing - however, the building model can only be further processed to a limited extent. Therefore, it is recommended to submit a change request to the architect in case of a change request from the project participants. IFC is available in different versions. Since 2013, IFC4 has been an international standard as ISO 16739. IFC4.3 is the latest Open BIM standard, this is currently on its way to worldwide accreditation, version IFC4.4 is currently being developed. Data is exchanged using IFC files with the extension (*.ifc), but files in the XML standard (*.ifXML) and zipped files (*.ifZIP) are also used.
How is an IFC model structured?
IFC models include geometric and non-geometric entities, they contain the building geometry and the data associated with the elements. In the IFC schema, certain classes are defined that describe building components such as walls or ceilings, and in the end represent the entire building model. Each individual class can contain additional information. IFC classes are initially structured hierarchically as follows:
- ifcProject: contains information about the project
- ifcSite: contains information about the site
- ifcBuilding: contains all necessary information about the building
- ifcBuildingStorey: contains information about the floors
- ifcBuildingElements: contains objects according to further IFC classes
In addition, the individual components of the building (walls, columns, ceilings, windows), the building services (boilers, burners, pipe systems) and the structural design (reinforcement bar, reinforcement mesh, built-in part, etc.) are divided into classes.
What is Model View Definition?
Model View Definition, or MVD, describes a subset of an IFC schema. It has the advantage that the entire building model does not have to be exchanged between the project participants, but only a filtered view with the necessary information. This facilitates and speeds up the process of data exchange. MVDs define geometric and semantic requirements and can also include dynamically defined property sets. These property sets, associated with the IFC model, can be predefined or customized (user-defined). Various MVDs are covered by buildingSMART, depending on the particular IFC version. MVDs can also be defined outside of buildingSMART, for example by individual clients. For example, an MVD can be exported for cost estimation or structural analysis.
Which software supports IFC?
Data exchange via IFC is supported by all BIM-capable modeling programs. The software provides the corresponding interfaces for import and export. Please note the supported IFC version. In the following we have listed some software examples, a complete list of the programs is provided by buildingSMART.
- Allplan Architecture
- AutoCAD Architecture
- liNear Revit
- Archicad
- BIM 360
- TRICAD MS
- Visoplan
- Vectorworks Architect
- BricksCAD BIM
Conclusion
The use of the IFC format offers several benefits and facilitates the Open BIM workflow. It enables collaboration between project stakeholders with the ability to communicate clearly and document and track changes to the digital model. The open, vendor-neutral data structure also provides the opportunity to access the information decades later. buildingSmart is still working on completing the comprehensive specifications of the individual building products and disciplines and subsequently anchoring new as well as important attributes there. IFC is currently a good standard for data exchange, but it will take some time before it is complete.
