BIM and building refurbishment

Bim and building refurbishment

György Halász (Budapest University of Technology and Economics)

Building Information Modelling (BIM) plays a major role in investments in existing facilities. In the case of buildings, point clouds, laser scanners (installed, mobile) and photos and videos taken with a drone technology are increasingly popular tools for documenting existing conditions.
The generated data (a set of spatial points and the colour information associated with the points) needs to be filtered according to the purpose of use. The accuracy of the survey (and hence the amount of data storage) must be adjusted according to the purpose. Subsequent conversion of the native file format may also be necessary. There are special softwares for this purpose.
The next step is to carry out the preliminary modelling with a relevant software, i.e. the documentation of the existing state of the building (BIM model). In some cases 3D documentation of the building under demolition may be the main objective, i.e. to preserve the model for posterity.

If the aim is to renovate the building, this should be taken into account in the modelling process. This means that the participants should define the level of detail in general terms and broken down into individual elements (LOD, LOI). In addition, the development of the modelling strategy is an important task. For example, the positioning of the model in the coordinate system, the treatment of the modelled individual spatial elements (what to model, how to model elements, into which parts to decompose spatial complex shapes), the amount of information to be added to the elements, the output formats (pdf, ifc, image formats, native format, etc...).
The model prepared in this way is then managed by a number of specialised teams, since renovation often involves expansion and changes of function, and design competences are multiplied. During the design process, several rounds of information exchange (EIR) are necessary as the content changes and becomes more precise. To achieve this, it is necessary to determine before the design process whether the design will be done in Closed BIM or Open BIM, as this will determine the data exchange method and file format. There is also a question how the so-called merged model is handled, whose responsibility it is to check the correctness of the model and other data generated, and where the modelling boundaries between the different disciplines are.

The result is a complex database, where the focus is now much more on the data, of course based on the essential model. A nice visual image is no longer a sufficient expectation of BIM (nor is it a close part of the BIM mainstream. In a professional sense it is more of a separate profession with its own specific high-end software background). Of course, visuals and a model that can be walked through with VR technology will help in the saleability of the project, but many more participants will use the data set associated with the model and the benefits of its interactive modifiability. Managing these requires IT background and knowledge as much as engineering competence.

It should not be forgotten that with the advance of simulation and parametric design, today's computer facilities are increasingly helping us to support structural engineering estimates, optimal formal ideas, natural structural patterns with complex calculations, and to make the best use of the structures used. In this, the machine shortens the time-consuming mental capacity involved, thereby multiplying our choices.