The so-called open format IFC (Industry Foundation Classes) is positioned as a standard to ensure interoperability between different CAD (BIM -) systems. Its development was carried out within the framework of organizations that were created and controlled by major CAD vendors. Based on the IFC format, two CAD- companies in 2012 developed the marketing concept of OPEN BIM (А. Boiko, “Lobbykriege um Daten im Bauwesen | Techno-Feudalismus und die Geschichte von BIMs,” 2024).
IFC (Industry Foundation Classes) is an open standard for data exchange in the construction industry, designed to ensure interoperability between different CAD – (BIM-) systems.
Open BIM – concept involves working with information from CAD databases and exchanging information between systems through an open format for exchanging CAD data – IFC.
The Open BIM Program is a marketing campaign initiated by… [1 CAD vendor],… [2 CAD vendor] and other companies to encourage and facilitate global coordinated promotion of the OPEN BIM concept throughout the AEC industry, with consistent communication and common branding available to program participants.
– From CAD vendor website, OPEN BIM Program, 2012 (CAD Vendor, “OPEN BIM Program,” 2012)
IFC was adapted by the Technical University of Munich from the mechanical engineering format STEP in the late 1980s, and later registered by a major design company and a major CAD-vendor to form the IAI (Industry Alliance for Interoperability) in 1994(Wikipedia, “Industry Foundation Classes,”)(Fig. 6.1-4). The IFC format was developed to provide interoperability between different CAD -systems and was based on the principles laid down in the mechanical engineering format STEP, which, in turn, emerged from the format IGES, created back in 1979 by a group of CAD users and vendors with the support of NIST (The National Institute of Standards and Technology) and the U.S. Department of Defense (Wikipedia, “IGES,”).
However, the complex structure of IFC, its close dependence on the geometric core, as well as differences in the implementation of the format by different software solutions have led to many problems in its practical application. Similar difficulties – loss of detail, limitation of accuracy and necessity to use intermediate formats – were previously encountered by mechanical engineering specialists when working with IGES and STEP formats from which IFC was derived.
In 2000, the same CAD -vendor that registered the IFCformat and created the IAI (later bS) organization, publishes the Whitepaper “Integrated Design and Manufacturing: Benefits and Rationale” (ADSK, “Integrated Design-Through-Manufacturing: Benefits and Rationale,”). The paper stressed the importance of maintaining full data granularity when exchanging between programs within the same system, without using neutral formats such as IGES, STEP [identical to IFC]. Instead, it was proposed that applications should have direct access to the underlying CAD database to prevent loss of accuracy of information.
In 2002 the same CAD vendor buys parametric BOM product (Fig. 3.1-18, more details in of the third part) and on its basis forms the BIM concept. As a result, only closed CAD formats or the IFC format (STEP) are used in the exchange of construction project data, the limitations of which were written about by the CAD vendor himself in 2000, who brought this format to the construction industry.
A detailed history of the interaction of more than 700 development teams involved in building data creation and processing tools is presented in the map “The Evolution of CAD (BIM)” (А. Boiko, “History of CAD (BIM),” 15 Dec. 2021).
The open form IFC consists of a geometric description of the design elements and a description of the meta-information. Various methods are used to represent geometry in IFC format, such as CSG and Swept Solids: however, the parametric representation BREP has become the leading standard for transferring element geometry in IFC format, as this format is supported when exporting from CAD- (BIM-) programs and allows for potential editing of elements when importing IFC back into CAD programs.
