by Richard McPartland
What is IFC?
Industry Foundation Classes, or IFC for short, is a global standard used to describe, share and exchange construction and facilities management information.
As a data format IFC is neutral (not the product of or favouring any particular vendor) and non-proprietary.
IFC is one of five types of open standard in the buildingSMART portfolio that each perform different functions when it comes to the delivery and support of assets in the built environment.
Using IFC means that construction professionals can use the software application(s) of their choosing to work with data. IFC is supported by about 150 software applications worldwide and this kind of interoperability is crucial as construction becomes increasingly collaborative.
IFC is supported by about 150 software applications worldwide and this kind of interoperability is crucial as construction becomes increasingly collaborative.
Why is interoperability important?
BIM is more than just ‘technology’, but perhaps it is the development in the transfer of digital information that is providing the impetus missing in previous construction industry initiatives, such as the responses to the Latham and Egan reports into the industry. To achieve BIM’s full potential the industry requires a robust mechanism to exchange the ever increasing levels of digital data, regardless of what software package or BIM platform is used.
There are two ways you could approach the issue. You could opt to deliver what you do using proprietary product(s) from a particular company or, alternatively, deliver assets using open file formats.
Opting for a vendor with a certain degree of market dominance will likely get you a suite of interconnected products that will, with a little tweaking, deliver the outputs you require. Others on the project team may well be using the same tools and will be able to access your files with relative ease. Those who aren’t will likely be able to convert files retaining all (or most) of the information contained within and can then use these assets in the system(s) that power their own workflow.
Investing heavily in a vendor’s own file formats does leave you committed – the vendor may opt to change its format, removing features, functionality or data fields or types that you currently rely on. If development moves further adrift of your requirements cutting loose and migrating data could prove tricky.
Opting for openBIM instead, an open and documented data format allows for easy data exchange and the ability to import data into the tool(s) of your choice. Use of a standard format should also buy you a degree of surety when it comes to being able to access your data in the years ahead.
It’s important to point out that use of IFC itself is no guarantee of interoperability. Though obviously designed to facilitate sharing of data there is a reliance on software vendors to support and properly interface with the format.
To achieve BIM’s full potential the industry requires a robust mechanism to exchange the ever increasing levels of digital data, regardless of what software package or BIM platform is used.
What kind of data?
Essentially speaking, IFC provides the ‘guidelines’ or ‘rules’ to determine what information is exchanged between applications while maintaining meaning. Although it may include geometry, it is not limited to this; it presents tangible building components such as walls and doors and also enables the linking of alphanumeric information (properties, quantities, classification, etc.) to building objects and maintaining these relationships.
IFC provides a set of definitions for all object element types encountered in the building industry and a text-based structure for storing those definitions in a data file. Design packages will typically store data in their own specific file format and offer a 'Save to IFC' option. The ability to import IFC files and map data to the system's own representation of objects is also provided.
IFC files can be output and exchanged between software products using the .ifc, .ifcXML and .ifcZIP file formats.
IFC provides the ‘guidelines’ or ‘rules’ to determine what information is exchanged.
What's the history behind IFC?
The history of IFC can be traced back to 1994. IFC was an output of the Industry Alliance for Interoperability, a consortium founded by Autodesk. The consortium became the International Alliance for Interoperability in 1997 and is now known as buildingSMART – a not-for-profit organisation that describes itself as the international home of openBIM. It promotes IFC as a neutral product model supporting the building lifecycle and opens up membership to all interested parties.
In 2013 IFC was registered with the International Standardisation Organisation as ISO16739 ‘Industry Foundation Classes (IFC) for data sharing in the construction and facility management industries’.
The IFC schema is regularly evolving with the current version, released in 2013, known as IFC 4. [Prior releases were labelled 1.0, 1.5, 1.51 then 2x, 2x2, 2x3 but a change in naming convention means what would logically have been IFC 2x4 is actually labelled IFC4.]
IFC4 extends support for parametrics and geometries, extends the building services and structural domain and offers a simple XML format. IFC5 is in the pipeline with further provision for parametric capabilities and inclusion of the infrastructure domain.