IFC (Industry Foundation Classes) are a vendor-neutral data repository for building information models (BIM) including both geometry and properties of ‘intelligent' building objects and their relationships, thus facilitating the sharing of data across otherwise incompatible applications. BuildingSMART International, formerly known as the International Alliance for Interoperability (IAI), is an organization of building industry stakeholders responsible for the specification and management of IFC, an industry standard for data interoperability across Building Information Modeling (BIM) applications used over a building's life cycle. This standard is regarded as a prerequisite for improving building workflows using BIM methods, thus eliminating the high cost and waste created by inadequate interoperability. Bentley is fully committed to the objectives of buildingSMART and is involved in several regional buildingSMART chapters and alliances as well as in IFC-related projects and initiatives, e.g. the adoption of IFC-based BIM technology by the US General Services Administration (GSA) and the OGC (Open Geospatial Consortium) AECOO-QTO testbed. Bentley's IFC2x interface was certified in 2003, and in March 2007, Bentley Architecture officially passed the certification for IFC2x3. Built on the Bentley Building technology platform, the IFC interface is also supported by Bentley Structural, Bentley Building Mechanical Systems, and Bentley Building Electrical Systems.
Fragmentation among project participants (architects, engineers, manufacturers, contractors, owner/operators, ...) and the lack of standard file formats for applications (CAD, BIM, FM, analysis, engineering document management, ...) is costing the building and construction industry virtually billions in lost productivity, wasted materials, and increased liability. In their 2004 report ‘Cost Analysis of Inadequate Interoperability in the U.S. Capital Facilities Industry', the NIST (National Institute of Standards and Technology) estimated the cost of fragmentation and lack of standards to be about US$15.8 billion or about 1 - 2 % of the industry's revenue.
In 1995, the IAI (‘International Alliance for Interoperability' or in Germany ‘Industrieallianz für Interoperabilität') was founded to define and develop an industry-standard, vendor-independent, and neutral file format for data interoperability across software applications used for design, construction, procurement, maintenance and operation. The key objective of this initiative was to improve communication, productivity, delivery time, cost, and quality throughout the whole building life cycle by facilitating the sharing of relevant information by project participants regardless of the applications they use. Organizations within the alliance now include architects, engineers, contractors, building owners, facility managers, manufacturers, software vendors, information providers, government agencies, research laboratories, universities and more.
Increasingly, buildingSMART is seen as a key driving force in the industry, as organizations such as the General Services Agency (GSA), the US Army Corps of Engineers, major owner/operators, and some large architectural and engineering firms are more and more demanding the specification, development, and implementation of an industry standard for interoperability between BIM applications. Greater interoperability is a prerequisite to significantly improve building processes, thus avoiding the high cost and waste as the result of inadequate interoperability. The IFC data model is regarded as the key enabler to achieve such interoperability, thus to overcome the inefficiencies of a distributed and fragmented industry.
BuildingSMART International is organized in Regional Alliances representing a country or a group of countries acting together. Currently, buildingSMART International has Regional Alliances serving Australasia, Benelux, China, the French Speaking countries, the German Speaking countries (Germany, Austria and Switzerland), the Iberian countries (Spain and Portugal), Italy, Japan, Korea, North America, the Nordic countries (Denmark, Finland, Norway and Sweden), Singapore and the United Kingdom and Ireland.
Specified by buildingSMART, IFC (Industry Foundation Classes) is a vendor-neutral BIM data repository for the semantic information of building objects, including geometry, associated properties, and relationships, to facilitate
IFC is registered by ISO as ISO/PAS 16739 and is currently in the process of becoming an official International Standard ISO/IS 16739. It is an object-oriented database of information that enables data sharing via ifcXML and aecXML. IFC-compliant applications can import IFC files and (re)use ‘intelligent' data created in other IFC-compliant application, and export ‘intelligent' model information as IFC files for (re)use in other applications. This is especially effective for interoperability between authoring applications, such as Bentley Architecture, and analysis applications, for instance to calculate quantities and costs, heat loss, cooling loads, lighting requirements, etc.
IFC are the ‘lowest common denominator' of all involved applications, therefore, high-end functionality in some applications is being reduced to the level of functionality that all applications can support.
So-called ‘round tripping' of IFC data, i.e. importing an IFC-file into the application which exported it or any other IFC-compliant application without any loss of data or functionality, is neither a current objective of the IFC2x3 Extended Coordination View nor a certification criteria, requirement, or use case for a number of reasons:
The only requirement for round tripping of IFC data is the preservation of GUIDs, even if IFC entities are downgraded to proxies and the geometry is converted to more basic geometric representations. Therefore, when a Bentley Architecture model is exported to IFC, then imported back into Bentley Architecture, it is no longer identical to the original model; hence certain application functions no longer work as before.
Thus ‘round-tripping' is an unrealistic and unjustified expectation by some people and organizations.
As a founding member of the IAI, Bentley is active at board level in several chapters (US, UK, and Germany). We provide significant funds for the definition of the IFC data format and spend considerable development resources to develop the IFC interface for the Bentley Building applications.
In May 2003, Bentley's IFC2x interface for the 3D Coordination View was certified, which allows import and export of ‘intelligent' 3D building models. Bentley did not apply for IFC2x2 certification, because this version, although used on some projects, is specifically aimed at support of the automated Code Checking system in Singapore.
In March 2007, in accordance with the official IAI facilitated approval procedure, Bentley Architecture 8.9.3 passed the certification for IFC2x Edition 3 (IFC2x3), which is based on the Extended Coordination View definition. As the IFC interface is built on the common Bentley Building technology platform, Bentley Structural, Bentley Building Mechanical Systems, and Bentley Building Electrical Systems effectively also support IFC2x3.
For export to IFC, family/part definitions of Bentley Architecture objects are mapped to IFC entities via IFC-mapping files. 3D levels and symbology of objects imported into Bentley Architecture, unless specified in the IFC file, are determined by the family/part definitions in ifc_imp_parts.xml or ifc_si_parts.xml, which are delivered with every localized dataset. These also define drawing symbology, rendering properties, and quantity takeoff rules of imported objects.
IFC2x3 supports common property sets, i.e. object attributes agreed upon by the Model Support Group of the buildingSMART and the IFC implementers. Bentley Architecture handles these properties through an IFC-specific DataGroup schema, which can be downloaded from SELECTservices and appended to a Bentley Architecture or project dataset. Non-common properties can be accommodated by customizing the Bentley Architecture DataGroup schema.
In addition to the Coordination View, there is a Building Services View and a Structural View in the early stages of specification.
The Structural Schema will not be defined until after the IFC2x3 certification and no official certification timeframe has been scheduled. However, Georgia Tech developed and is making available a free translator to exchange CIS/2 and IFC data as well as information and test cases. Therefore, Bentley will focus development effort on the CIS/2 interface provided with Bentley Structural.
As there are no Building Services or Structural Views yet to support, IFC cannot be used to export to or import from any mechanical or structural analysis applications. However, generic 3D geometry of Bentley Structural and Bentley Building Mechanical Systems can be exchanged using part mapping to IFC entities, like IfcBeam and IfcFitting, as the Coordination View supports generic structural and mechanical items.
Bentley is and was involved in a number of IFC-based project initiatives, such as:
For Bentley, IFC are just one way to share information and interoperate with other CAD, BIM, and analysis applications, as we provide
For further information, see ‘Bentley's Commitment to Open Standards and Interoperability'.