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As Building Information Modelling (BIM) becomes more prevalent in the construction industries of the world some of the practical problems of authoring and sharing models are also becoming more evident. It is generally accepted that BIM-related technologies offer considerable advantages to many, perhaps most participants in the construction sector (Eastman et al., 2008). In the UK, for example, the Government has mandated the use on all its projects of ‘fully collaborative 3D BIM … as a minimum by 2016’ (Cabinet Office, 2011).
A fundamental limiting factor in the uptake of BIM is the issue of interoperability, defined by the International Alliance for Interoperability (IAI, now ‘buildingSMART’) as ‘an environment in which computer programs can share and exchange data automatically, regardless of the type of software or where the data may be residing’ (see Fischer & Kam, 2002: p.14). Currently, there exists a whole range of commercially available BIM software platforms that have developed to suit the functional needs of their current main users (architects, structural engineers, services engineers, constructors, and so on) and consequently differ structurally and semantically. The aspirational ideal of fully collaborative BIM presumes a single model, allowing the full integration of all aspects of the design and further, for the same information to be re-used in the delivery and operation of the constructed facility. To do this effectively, secure and reliable exchange of data is essential. It is this requirement that underlies the concept of ‘interoperability’, or more specifically ‘semantic data interoperability’ (Yang & Zhang, 2006). As Cerovsek points out a key issue has been how to achieve ‘inter-operability between multiple models and multiple tools that are used in the whole product lifecycle’ (Cerovsek, 2011: p. 224) and BIM usage is still largely restricted to discrete models that relate to the contribution of each of the disciplines involved: currently, as evidenced by NBS’s National BIM Report (NBS, 2012) full collaboration is still far from a reality.
For some time the recognised basis of BIM interoperability has been the system of Industry Foundation Classes (Ifcs) designed by the International Alliance for Interoperability and maintained by buildingSMART (Tolman,1999; Fischer & Kam, 2002). However, the mere presence of Ifc is not sufficient for overcoming the problems of interoperability, and, for some critics, data exchange remains ‘unreliable and unpredictable’ (Sacks et al., 2010, p. 420). Fischer and Kam (2002) identify such problems, particularly when they result in ‘geometric misrepresentations across different software packages reading the same IFC source file’ (Fischer & Kam, 2002, p. 40).