Whats is IFC?

All you need to know about IFC

What is IFC?

IFC stands for Industry Foundation Classes which is a file format and standard developed by BuildingSMART. IFC is a type of file format used in BIM contexts so that different people can collaborate on the same project, even if they use different BIM software. It is an open, international file format, which makes it possible to, for example. a designer to use an A-model created in Revit, even if the designer uses another software.

IFC is a standard for BIM data that includes definitions of the data required for building and infrastructure projects, throughout the life cycle of projects. The file contains all or part of the information contained in the source file. It is by that a data model that contains a mixture of geometric and non-geometric data and that translates identities in a logical and standardized way. Examples of these identities can be names, unique IDs, properties and attributes, connections, objects, processes and some other things to a given structure.

Exporting a source file to IFC is a way of translating data into a common standard.


what is ifc


How is IFC used?

IFC is often used to exchange data between different people. Different contractors can, for example, be assigned an IFC file from an architect to use as a reference file for their own design.

With the help of IFC files, several disciplines’ models can be merged into a common model that can, for example, be used to perform collision checks in.

IFC can also be used to archive project information, both during design, through construction or as a database during the management of the completed project.

Something that is good to know is that an IFC file is a slightly “stupider” file than its original, as you export the model and your project components some of its intelligence and flexibility when exporting.


What are the different types of IFC formats, and which should I use?

IFC data can be written in different formats, where the formats have different advantages depending on the purpose of the file. Two important aspects to consider are the scalability and readability of the file.

The most common, and most widely recommended format to use, is the one that only has the suffix ifc. Sometimes it can also be written as IFC-SPF. This format is based on ISO standard 10303–21, and is called a STEP file. This is the most compact of the formats and can be read as text.

In addition to this, there is also the ifcZIP format, which is a format for compressed IFC files and has a much smaller size than a regular IFC. This format can be read by most software that can also read IFC. ifcZIP files can also be unpacked and make the compressed IFC file available.

IFC data can also be written in other formats, such as XML and JSON for example.


What is the difference between IFC2x3 and IFC4?

IFC2x3 and IFC4 are different releases of the standard, where IFC4 is the latest version but where both are currently used. The version that will follow IFC4 will be called IFC5.

The version most commonly used today is IFC2x3, which will probably be the most dominant version to use at least for some time to come. This is partly due to the fact that many ongoing projects per requirements are bound to use IFC2x3, and that it often takes time to develop support for new versions of the BIM software. This means that there is a certain delay before a new version can be used on a wide scale. With that said, there is support for both the export and import of IFC4 in later versions of Revit.


How do I open an IFC?

If you have a BIM software, such as Revit, you can open your IFC file in it. Opening an IFC file is usually not recommended, since the model loses some intelligence when the file is exported to IFC. If you still need to do this to, for example, continue editing in the file, you can do so after you have opened it in Revit. When you import an IFC file into Revit, all elements contained in the file are translated into Revit objects. If the file is large, this may take a long time.

  • For Revit, go to File, select Open, and then select IFC. This will open your IFC file.

If you want to use your IFC as a reference file instead, you can link it to your Revit project. If you link to an IFC, a Shared Parameters file will be created in your folder where you have your IFC saved. You can use this to, for example, create filters in your model.

  • With your project open, go to Insert, and select Link IFC.

If you have access to Autodesk Docs, you can also review your IFC files there. If you do not have access to Autodesk Docs or any BIM software, you can use Autodesk’s free web viewer. Link to it can be found here: Autodesk Viewer | Free Online File Viewer.

There are also various free viewers that can be downloaded to view IFC files in. One that is recommended by Autodesk is FZK Viewer from KIT: KIT – IAI – Downloads – FZKViewer.


How do I create an IFC?

IFC is a platform-neutral file format that can be exported and opened from most major BIM software, such as Revit or AutoCAD Architecture.

To create an IFC in Revit:

  • Load your IFC mapping file that you want to use in your export. Read more under the paragraph “What is an IFC Mapping File?”
  • With your file open, select File, Export and then IFC
  • Name the file and select a location to save it
  • Select the Setup you want to use. Read more under the paragraph “What is MVD and which Setup should I choose?”
  • Select Export


What is MVD and which Setup should I choose?

MVD stands for Model View Definition and can be seen as a filter for your export. However, as the point of IFC is to translate data from one format to another, not all data actually needs to be translated. What information is needed sometimes depends on the stage of the project you are in or what the purpose of the file is.

The requirements and need for information differ, for example, if you are to use it for coordination or to perform analyzes.

IFC2x3 Coordination view is the format most used. The primary purpose of this MVD is to create a file for visualization and collision checks. This is an option available only for IFC2x3. In IFC4, they have instead chosen to divide this into separate MVDs: IFC4 Reference view and IFC4 Design transfer view. For Revit 2022, the IFC4 Reference view is also available for separate disciplines.

IFC4 Reference view is usually used when the purpose is to create an IFC that will only be used as a reference file. It is not suitable to use if the purpose is to continue working on the geometry, as it contains only the most basic geometric definitions.

IFC4 Design transfer, on the other hand, is better intended as the recipient is expected to edit the file.

IFC2x3 COBie 2.4 Design Deliverable follows the COBie standard that is often used in the transfer of project data from design to operation and management.

These setups are predefined and cannot be edited, renamed or deleted. However, if you need to make individual settings for your export, you can duplicate and edit a copy of the existing setup.


What is an IFC Mapping File? 

For import and export of IFC, there are two different Mapping tables. These are structured lists of how all Revit categories are translated to IFC, or equivalent from IFC to Revit. This file is saved in text format and can be edited either inside Revit or in a text editor.

what is ifc

The first column is all Revit categories and subcategories. This column cannot be edited. The second column describes which IFC classes each category will be translated to.

If a category is not to be translated, you can type Not Exported for that category. The classes that are supported are continuously updated and the list in Revit must be defined in accordance with these, and with the correct spelling. Current list for Revit 2022 can be found here Help | Supported IFC Classes | Autodesk.

IFC Type can be used to get a higher level within a definition for a category and can be compared with the corresponding subcategories in Revit. These must also be defined in accordance with current classes.

By default, a predefined Mapping table is used, which is saved at: C: \ ProgramData \ Autodesk \ RVT (version) \ exportlayers-ifc-IAI.txt.

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