What is IFC?

By Mark Baldwin 3 years ago
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IFC, or industry Foundation Classes, is a standard, some would say the primary standard, for openBIM data exchange.

IFC is commonly referred to as an exchange format. This is not entirely correct. Firstly, IFC is a schema, not a format. But that is probably a discussion for another time. Let’s focus on the exchange part. The current IFC workflow doesn’t support data exchange to the extent that I can start modelling in one software, make an IFC export to another application and continue modelling uninterrupted. It’s more accurate to think of IFC as a means of referencing or archiving model content.

In the previous video of this series we presented IFC as the PDF of BIM. Like PDF, an IFC file is a frozen copy of the original content. It can be viewed, measured, used for clash detection, cost estimation, simulation and innumerable other uses, but should not be edited.

An typical IFC workflow could be the following:
An architect creates their design model and exports an IFC version to share with the HVAC engineer. The HVAC engineer can reference this file into their own software and use this for coordination. More than that, the engineer can also use the IFC model as a basis for energy analysis. Which is pretty impressive. The IFC transports enough information for the simulation software to read and analyse the IFC spaces in the referenced model.

What the engineer can’t do, however, is make a change to the referenced model. For example, if they want to move a wall, or create an opening in the wall for an air duct to pass through, they must request that change from the architect.

The architect, back in their own modeling software, then cuts the opening in their model and issues a new IFC file.

It must be said, that it is technically possible to edit an FC model, but that is not the intended workflow. Almost all software that import IFC treat the IFC model as referenced copy of the original design. Some tools allow you to make minor edits to an IFC model. For example splitting a concrete slab element for construction phasing, but this is an isolated activity and has no effect on the original design model.

The point is that in an IFC-based workflow each discipline remains author and owner of their model content.


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  BIM Software

 Mark Baldwin

  (12 articles)

Australian architect and BIM-specialist. I am drawn to the simple, the pragmatic and the innovative. BIM - the digitalisation of our construction industry - must be all of these things.