Identifying objects, in general and in projects

One of the most basic things in BIM is identifying objects, i.e. asking what an object represents. When an object is identified it becomes ‘machine readable’, which is the big difference between BIM and documents. IFC has object classes, predefined types etc. that can be pointing in the right direction, but identification is not that straight forward.

One approach that has helped me is to differentiate between ‘general identification’ and ‘project specific identification’.

• Objects often have information about what they are in a general sense, like ‘partition wall’. General identifiers are great because they always stay the same and any data wrangling automation that is based on general identifiers can be re-used across projects.
• But when you dive into the details, for example when you are taking off quantities, then you are not counting and measuring these generic things. Instead you are using identifiers that can only be understood in the context of a project. For example when the type of a partition walls is ‘IW-1’ it does not mean that ‘IW-1’ has the same meaning in different projects. Instead you need to know what ‘IW-1’ means in the project you are calculating at the moment. The meaning of these project specific identifiers is most often documented outside the model. But even if they are not documented they tell that the intention is that for example two partition walls are different because they have a different type.

One good approach is to use the general identification first and then sub-divide the object groups created this way using the project specific identifiers. For example like this:

• Partition Walls
  • IW-1
  • IW-2
  • …