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COBie (Construction Operations Building Information Exchange) is at the heart of the Government's Construction Strategy (GCS), requiring fully collaborative 3D BIM with all project and asset information, documentation and data being delivered electronically by 2016. It provides a means of delivering interoperable data, mainly information relating to the operation and maintenance of a building, between interested parties.

COBie, a subset of IFC, was developed in the US and subsequently taken on over here, restructured slightly in the way it handles the exchange of some of the information, to provide the answers to key questions (the American version, for instance, doesn't include data on carbon emissions, etc.).

COBie information is compiled on a spreadsheet, allowing many people to find it easy to address because of their familiarity with the technique. The Government, after all, has to sell the idea into an area where there have already been some IT-related disasters, all based round Excel based systems.

COBie has another mountain to climb. One of the hardest things in any industry is for professionals to get used to structuring what they are doing and allowing it to be used by others further down the line. Hence the main criticism of COBie, in that it represents a huge amount of information being presented in a rather strange format to the one that architects and engineers traditionally use. In fact, there is no particular reason why any relational database can't map a field in a BIM model as easily as it would in an Excel spreadsheet - and with regard to shareable data, the code 1502 will always be a concrete pile whether it relates to the model, an IFC element or the contents of an Excel data cell.

Although some in the industry believe that It might have been better to go straight to IFC, with a more direct relationship to the 3D model, the BIM Task Group, charged with shepherding the strategy through, believes that an Excel based system is perfectly valid as an intermediate step.

EARLY STAGES
All of this pontification is fairly new. It is only recently that the first stab at defining the real requirements for UK BIM have borne fruit, and with it COBie. As it stands, contractors have to complete a number of different forms that relate to the Level of BIM they have achieved on a project (with a full definition of Level 2 yet to be published), referred to as 'Drop, numbers 0 to 4'. The first, COBie Drop 0 relates to setting up the spreadsheet, what is in it, and which field is related to which element.

Besides contractors having to fulfil BIM requirements, software developers have to ensure their software allows graphical data to be converted and used in spreadsheet format, and as we have seen, the IFC format appears to be the easiest way to achieve this. Except that different software vendors have inherent issues that govern the IFC output they can produce.

To take two examples, whereas Graphisoft is capable of creating pretty generic IFC ouput, the way in which Autodesk's Revit stores information about data fields is different to Graphisoft, its internal data structures limiting its IFC import and export capabilities, and is insufficiently documented for it to be used as a COBie conduit. Autodesk is working on a solution to this through the BIM Academy, using intermediate routes. Hence, whilst both Revit and ArchiCAD are IFC 2x3 certified, Revit's version won't allow the import and export of such file formats.

STRUCTURED DATA
To confuse the situation further, we have more levels of BIM to climb, leading up to what is known as 'Structured Data'. This refers to information that lies beyond the BIM model and which relates to the role or function of a building - it is estimated that 80% of the information required for COBie is required for a facility after handover. Structured information provides rather more detailed information than an architect is used to giving. It has to be added by services and maintenance engineers or manufacturers further down the line.

To give an example, a light fitting over a stairwell will require a different level of maintenance support to change the bulb than one in the middle of a room. Different levels of costs are involved, which, if repeated over the lifetime of a building, could run into thousands of pounds. To handle it, an architect can define and label a space - but someone else has to define its function.

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