The term BIM seems to have been coined by Autodesk, a leading software vendor for AEC (Architecture, Engineering and Construction) applications. However, Graphisoft claims that their Virtual Building concept introduced with ArchiCAD in late 80’s was the first ever implementation of BIM concept in an AEC application [read Laiserin 15 & 19].

The development of BIM can be traced back to the initiatives of the International Alliance for Interoperability (IAI). IAI started as Industry Alliance for Interoperability in 1994 as a consortium of group of US companies. They demonstrated interoperability among some CAD (Computer Aided Draughting) and simulation tools at the AEC Systems Show in Georgia in 1995. It became global organization in 1996 and changed its name to International Alliance for Interoperability. In 2005, it was renamed to buildingSMART.

buildingSMART's mission is to “Contribute to sustainable built environment through smarter information sharing and communication using open international standards in the building and construction sector, private and public”. The keywords here are “information sharing and communication using open international standards”. Thus, it intends to eliminate communication boundaries between software applications, operating systems and languages. BuildingSMART is a not-for-profit organization. The organization is responsible for developing and maintaining international standards for openBIM – an open source - free to use - BIM standards. These standards cover

These are explained briefly below. Reading through this will help you to understand how BIM works.

The Processes

The construction industry is characterized by many different parties brought together in a temporary multi-organization (TMO) for each individual project. They share many different information in variety of formats. For work efficiency, it is important that parties know which and when different kind of information is to be communicated. This becomes critical when digital tools are used, because these tools have very low threshold of tolerance in data interpretation ability, compared to the human brain. BuildingSMART develops “Information Delivery Manuals” (IDM) as ISO standards (currently ISO 29481-1:2010 “Building information modelling - Information delivery manual - Part 1: Methodology and format”) in order to have a methodology to capture and specify processes and information flow during the lifecycle of a building. The main purpose of an IDM is to make sure that the relevant data are communicate in such a way they can be interpreted by the software at the receiving side [read Karlshøj].

The Data Dictionary

BuildingSMART develops the standards for terminology libraries or ontologies, known as International Framework for Dictionaries (IFD). IFD is not just a dictionary; instead, it defines the framework for development of data dictionaries for BIM technology. IFD is a structure which can hold many dictionaries (terminology libraries or ontologies). The concept for the IFD Library is derived from internationally-accepted open standards that have been developed by ISO [read Bjørkhaug & Bell]. Software developers use this framework to develop BIM enabled software. Since interoperability is inherent feature of BIM, IFD will assure interoperability among these software.

The Data Model

The data exchange format for openBIM is called Industry Foundation Classes (IFC) [read at buildingSMART Tech]. This data model is supported and complies with IFD (described above). In simple, IFD specifies concepts and IFC is used to define the individual instances of the concepts. For example, IFD may define how to specify a wall, IFC specifications for certain type of a wall is specified accordingly, and in an IFC product model it may have defined the location and geometries (and much more information) of said wall type in a particular building. IFD holds the templates while IFC standards are used to fill them in [again in Bjørkhaug & Bell]. The IFC can be called the master file format of a building project.

IFC is in fact an EXPRESS based entity-relationship model consisting of many entities organized into an object-based inheritance hierarchy. IFC consists of an information schema, i.e. a data model in a formal machine-readable notation, and associated informal human-readable semantic definitions [read buildingSMART FAQs].

The scope of IFC schema is to define a specification for sharing data throughout the project life-cycle, globally, across disciplines and across technical applications. This is enormously broad and complex. Therefore most BIM applications use a sub-set of IFC schema depending on their requirements. Software applications have their inherent information schema. Importing from and exporting to IFC involves mapping of their internal information schema with the IFC schema. Because of the differences in the two data schemes, data losses can occur during the translation process. This may be one of the reasons why proprietary BIM information schemas such as that is used in Autodesk’s Revit, are also becoming popular.