Recently, there has been an increase in the number of projects for which "as-built" models have been requested. Some of these are for buildings that have recently been constructed or are due to be completed in the near future; others are for buildings that have been in existence for some time. Many clients are hoping that a BIM model of their buildings will bring added value (which cannot yet be quantified) in terms of documentation and operation; these efforts are currently referred to as "pilot projects". What difficulties can arise when creating and using such an as-built model?
Searching for information on the existing property
Let's assume that facility management needs information about the existing building. There are now several ways to find this information.
The most time-consuming - but most reliable - way is to check on site in the building. Many building products such as windows and doors have markings so that you have very precise access to component information.
The second option, which is probably the most common, is to view the as-built documentation and obtain the required data from it. Depending on the type of building and the systematization of the document storage, this can also take a long time. If successful, however, the original document (or a digital version of it, e.g. scanned) is usually available.
As such a search naturally requires a high level of knowledge about the building itself and the filing structure, so-called CAFM systems have been developed in recent decades. The aim is to make it easier to maintain the relevant data and to find important documents more quickly.
Now that everyone is talking about BIM, as-built plans are to be raised to the level of a 3D model. The idea is that this will make the management and subsequent conversion of buildings even more efficient. Facility management staff can virtually walk through the building, "only" have to click on the desired component and a list with all the required information appears.
Confidence in the data situation
We always take the best-case scenario as our starting point for such considerations. We have complete, clear and correct documentation of our building and can transfer this seamlessly and correctly into a model. The original documents become obsolete.
But the problem is that this is hardly ever the case.
In many projects, as-built documentation is an "onerous" obligation at the end of the project. It is usually very extensive and can hardly be checked with the resources available. The difficulty lies in the fact that responsibilities change, namely from the construction project to operations. This means different people, different processes and different priorities. Years can pass before an error in the documentation becomes apparent.
So when push comes to shove, what information is most likely to be trusted? A model that (we have to be honest) has not necessarily been "traced" by the most highly qualified modelers on the basis of selected parts of as-built documentation? Whereby the information in such a model (if you read the proposed terms of use ) is only of a "non-binding" and "informative" nature? Or the original documents, which were unalterably created by those responsible for the project at the time. For the content of which manufacturers, construction companies and civil engineers are also (partially) liable?
Any post-processing and editing carries the risk of errors. Creating a 3D model from a 2D PDF requires precise knowledge of the building, as many things have to be interpreted by the modelers. Documents can contradict each other, and there is not enough time during model creation to deal intensively with all documents.
Any information that is entered into such a model is potentially incorrect. The documentation could already be incorrect, the latest status could not have been transferred, it could have been misinterpreted or - mistakes are human - a typo could have been made. Even more unpleasant: BIM programs generate "dummy" information because otherwise the geometry of a 3D model cannot be generated.
Conclusio
As the owner or operator of a building, such an approach would be far too risky for me. So should you just leave it at that? An alternative approach can be found in this article .
BIM is intended to prevent this documentation chaos for new projects, and that is of course desirable. However, the starting point for older buildings is different. The aim is to transfer validated information to a new system step by step and in a comprehensible manner. It would be fatal to generate the next media disruption here and thus allow further documents to be forgotten. There can be no "single truth" for existing buildings. The desired unambiguousness is (unfortunately) an illusion.
A building model (not necessarily with 3D geometries!) can assist in finding information (especially contradictory information) in existing documents, but it can never reliably replace them. If we simply see it more as a search engine than a source of information, then we are getting "closer to the truth".