How Industry Foundation Classes Lay the Foundation for BIM Collaboration

As the world of construction technology grows, the way data gets exchanged between solutions becomes increasingly complex. Particularly for large building information modeling (BIM) files, this can get sticky. 

Each platform generally has its own proprietary file format for its BIM files, but there’s no industry-standard software solution. As a result, an architect might develop the BIM model in one platform and then send it to engineers and contractors for use in their own different platforms. 

How, then, do these files get exchanged? Industry foundation classes — or IFCs, for short — enable that data sharing. Created and continually updated by buildingSMART, IFC has become the industry standard format for exchanging 3D BIM files. 

buildingSMART International (formerly known as the International Alliance for Interoperability [IAI]) operates from the United Kingdom and has chapters and partners around the globe. The group aims to drive and dictate standardization and file exchange for models. It stands behind other standards, but IFC is buildingSMART’s core program. 

In this article, we'll discuss what industry foundation classes are and how they apply across the architecture, engineering and construction (AEC) industry.

What are industry foundation classes (IFCs)?

Industry foundation classes are a schema that provides a standardized way to codify the characteristics and relationships of various model elements. That includes concrete components like slabs, as well as intangible concepts, like costing data. 

If CSI MasterFormat is the Dewey decimal system of construction, IFC is the PDF (portable document format). It’s a neutral file schema broadly used across the AEC industry to exchange data. Primarily, files formatted with industry foundation classes' schemas are 3D models, although IFC can be used for 2D files, too. 

Industry foundation classes BIM files are based on a set of open standards. Software providers adopt these standards so that the files created within their solutions can be exported in this format. That doesn’t mean, however, that an IFC file can be exported from one solution, then opened and worked with in another.

Instead, in the same way a PDF needs to be moved to a different file type to be edited, people working with IFC files import that file into their BIM authoring tool of choice. That creates a new file and a new model of the building from which they work. 

In other words, the IFC file isn’t a living document. Instead, it’s essentially an archive of the model content. It allows a static version of that model to be moved from one platform to another. IFC is the schema that maps data so the information from a model in say, Revit, can be exported and opened in ArchiCAD, for example. This schema is, in essence, a database of information that the solution opening the file can use to rebuild the model in its own platform. 

Because IFC is a set of open standards, it can — and usually is — adopted by construction software providers that offer BIM functionality. As a result, it enables the exchange of model data across a wide range of software solutions. That, in turn, makes it easier for all stakeholders on any type of construction project to access and leverage the model. 

Versions of IFC

To make industry foundation classes continually useful as building modeling evolves, buildingSMART continually releases new specifications. The most current official version of IFC is 4.3.2.0, also called IFC 4.3. 

buildingSMART has already started developing IFC 5 with the stated intent to refactor industry foundation classes BIM content. 

Construction software providers generally make an effort to adopt the latest schema, updating their own solutions to align with the latest official set of standards. That said, different companies have kept pace differently. As a result, some tools function best when the IFC file is formatted according to a specific schema, which the user can often choose as part of the export process.

To make it easier to determine which software providers offer IFC file functionality and which schema they currently adhere to, buildingSMART maintains a directory.

Note that the standards listed by vendors are self-reported by the software provider and not verified by buildingSMART.

Industry Foundation Classes and BIM: Use Cases

IFC has a variety of use cases across the AEC industry. As an open standard, it allows model data to be shared from the architect’s authoring tool of choice to the engineers, general contractors (GCs), and subcontractors. This allows for clash detection, simulation, cost and schedule planning and more. 

It’s also possible to export only a portion of the model as an IFC file. This allows GCs to coordinate with their trade partners on specific areas as needed. 

IFC files commonly get used to exchange complex structural steel models, for example. That modeling work is often done in Tekla, and an IFC file allows the architectural model to be brought into that platform. Then, that structural steel model can be exported from Tekla as an IFC file, enabling it to be used by the GC and any applicable subcontractors. 

Opening and Viewing IFC Files

Today, the party with whom the IFC file is being shared doesn’t necessarily need their own authoring tool software. Free online IFC viewers allow anyone with the file to open and see the model (these free viewing tools usually only work with files up to a certain size). 

IFC Usage After Construction Is Complete

Industry foundation classes can have use cases beyond the project’s handover to the owner, too. If the owner uses a computerized maintenance management system (CMMS) platform for facilities management, they can intake the model information into that platform as an IFC file. 

In this case, the contract documents should specify what the owner needs in the as-built model (e.g., all serviceable equipment). With industry foundation classes, BIM models can power efficient maintenance and ideally extend the structure’s useful life. 

The Advantages and Challenges of IFC

The industry foundation classes schema delivers one huge win: it enables collaboration across the entire AEC industry. IFC files allow stakeholders through each phase of the project to view and engage with the BIM model, regardless of the software their company has adopted. 

As an open standard, it facilitates data exchange across different authoring tools. IFC includes standard mappings so, for example, when beams are exported from a model in one tool, they get classified in the beam family. This allows the platform opening the IFC file to map those beams to the appropriate category and location. It keeps model information organized so that it can be most effectively used by each party. 

IFC files can present a few challenges:

• Potential for Multiple Versions of the Model

  Like a PDF, IFC files aren’t editable. They purely serve as a reference that allows the software to build the model in its own platform. As a result, if a user opens an IFC file in a new solution and makes changes, those changes are only reflected in their file. Nothing automatically kicks back to tell the party that sent the IFC file that a change has been made in the model. 

• Long Opening Times

  These files can be cumbersome. It might take hours to open a new IFC file in the user’s platform of choice. 

• Potential for Data Loss

  Because opening an IFC file in a new solution requires that solution to rebuild the model, the software may restructure data. In some cases, that data could be buried deeper than the user may think to look. 

Still, though, assuming the software provider adheres to the latest IFC schema, all of the data from one solution should get captured in the IFC file. Consequently, it should get represented when that file is opened — and the model is rebuilt — in a different solution. 

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Looking Ahead With Industry Foundation Classes

Industry foundation classes have become increasingly open, both in terms of data exchange and the ease of viewing the exchanged data. And as buildingSMART works to improve backend schema mapping and software providers work to comply, IFC files should get cleaner. Ideally, this will help them open faster and better display the data the user expects. 

To best leverage IFC, users need to adopt a spirit of collaboration. Many platforms allow the user to choose the IFC version in which they want the file to be formatted once it exports, for example. Inquiring about the ideal version for the end user’s platform of choice, then choosing to export in that version, can facilitate more effective data sharing. It also helps to have a plan to facilitate this collaboration. A good BIM execution plan establishes an information exchange protocol, outlining how files should be formatted to drive efficiency across the project.

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