Understanding BIM Data and File formats

The major selling point of BIM as a system of working has always been about collaboration. But how is data and information shared between people, systems and professionals in this 'collaborative process'?

In this our post today, we are going to be discussing the ways in which data is managed in a BIM workflow. We will be discussing the data formats used, whether proprietary (like .rvt, .dxf, etc), non-proprietary (like IFC) data sharing between software packages, OR data communication to humans using COBie. Now, let us explain what each of these mean and why they matter.

Proprietary file formats

These are file formats created by software manufacturers that are only readable/executable by their own software (or any another software they allow). A major example of this is the .rvt file format. This format works with all Revit software packages (Architectural, Structural or MEP), and those packages with which Autodesk have special arrangements, like Orion, but not software packages by other manufacturers like Tekla. Because of this, interoperability may be hampered.

Engineers and Designers, when working with specialist design software having proprietary data formats can use any one of these four options to coordinate between different software packages.

1. Remodel the chosen part (for example, a designed piping system with chosen specifications) in the main BIM authoring software (Revit or Archicad.)

2. Transfer the designed model (with all its properties)
 to the BIM authoring software if the makers of both software have a common file format for transfer between them (For example, structural engineering software, Orion, and authoring software, Revit have a CXL filetype for transferring data between the both of them.)

3. Convert the file to IFC format and send to the BIM authoring software. For this particular option, the integrity of the file being created has to be assured as there may be loss of data during conversion (that is, ensure all physical (3D information) and intrinsic information (such as quantities and types of materials) are maintained.)

4. Use a plug-in that connects the softwares which may have been developed by the companies, software resellers or independent programmers.

Non-proprietary file formats

These are file formats which are vendor-neutral (they can be read/edited by any type of software.) They are usually open source, with professionals from all over the world contributing input towards its development. For the BIM industry, the standard bearer in non-proprietary software is the Industry Foundation Classes (IFC), an open and neutral data file format. This format is being developed by the buildingSMART alliance, which coordinates the global effort towards improving the file format to capture more types of data.

There are 3 types of IFC file formats. These are;

1. .ifc: This is the default IFC file format

2. .ifcXML: This is an XML type file which is generated by sending application from an IFC data file using conversion according to ISO 10303-28, the XML representation of express schemas and data.
3. .ifcZIP: This is the compressed IFC file format created from a .ifc or .ifcXML file.

Another open source file format is CIS/2, which is used for steel projects


COBie is an acronym for Construction Operation Building information exchange. It is a data format (spreadsheet for short) that allows for multiple non-graphical/geometric (3D) data to be shared. It is used to transfer data and documents created during the design and construction to the facility managers.

COBie is not a file format as against proprietary and non-proprietary formats, rather, it just holds data in a human readable form. To better understand what COBie does, lets compare it to IFC. While IFC helps different software to understand and share BIM data, COBie helps humans understand and share BIM data.

The major advantage of COBie is the fact that it can be populated with data manually (by hand) or automatically (from BIM software). The output COBie spreadsheet is a human readable form of data gotten from the IFC model.

BIM authoring software like Revit and Archicad have functionalities for converting BIM models into COBie format.

Why does the data format and filetype even matter?

Typically, Engineering professionals and/or specialists work with specialist software made for their craft (structural engineers with Orion, Mechanical Engineers with Vectorworks, Civil Engineers with Autodesk Civil 3D, etc... so you get the point.)

But over the course of their work on a project, they need to exchange data/information with each other (for example structural Engineers knowing the positioning of the columns as designed by the architect, mechanical engineers using the building model to plan HVAC/plumbing systems, etc.)

A knowledge of the data and file formats and how it works will help the multidisciplinary design team make better informed decisions when choosing software packages, bearing in mind the need for collaboration.

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Understanding BIM Data and File formats Understanding BIM Data and File formats Reviewed by Izuchukwu Obi on 08:19:00 Rating: 5

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