Opinion

BIM For Renovation Projects

 

There is no insurmountable impediment to the application of BIM for renovation projects. However, despite all the benefits it can bring, it must be stressed that BIM for renovation projects necessitates specific procedures that are partially different from those required for new construction projects. 

If one googles the words 'BIM' and 'Renovation', one finds that around 99 percent of the results relate to 'Scan to BIM'. Nevertheless, 'Scan to BIM' is just one component of the solution: it assists geometric modelling, but contributes little to the definition of the physical and mechanical properties of building components, and to the identification of their constituent materials. Yet that information is as central to BIM as the letter 'I' is to that acronym. 

Speaking schematically and approximately, we could say that a building information model is a centralised electronic repository of information pertaining to the physical and functional aspects of a project. This repository of computable information evolves over the life cycle of a project. Essentially, BIM can be conceived of as a collection of ‘smart’ objects stored in an ‘intelligent’ database. BIM technology is object-oriented. 

Among the factors that have been fundamental to BIM’s success in the industry, such as data representation and exchange, is the availability of BIM content in the form of (smart) objects that can be used by project stakeholders to develop project-specific models.

These objects have three primary sources:

  1. BIM-authoring tools’ predefined objects
  2. In-house libraries of objects
  3. Online libraries of objects

The efficiency of a BIM model depends greatly on the quality and quantity of information that has been matched with the geometric model. Object-oriented modelling allows for extensive use of the data provided by manufacturers, which has facilitated the success of online libraries of BIM objects.

It is evident that this approach is unsuited to renovation projects – particularly those involving historic buildings – as information on the relevant architectural elements can be obtained only ex post facto through diagnostic methods, such as endoscopic, thermographic, single and double flat-jack, sonic and ultrasonic investigations.

For this reason, it is important that we consider a number of specific issues affecting the implementation of BIM procedures for obtaining real BIM models – not just beautiful 3D models – for renovation projects:

1. The BIM model should incorporate the diagnostic plan for the characterisation of building materials and related alterations.

2. For each object, a structure or building system should be specified if the data associated with it were obtained through diagnostic investigations performed on that specific element or on adjacent and/or similar elements. It would be appropriate to give a confidence rating to the BIM objects data.

3. LOD classification – that is, the specific resolution of graphical and non-graphical information required for a particular element at a particular phase of the project – should include a classification dedicated to renovation projects. This already exists in the Italian BIM standard UNI 11337.   

4. COBIe and other similar standards for BIM information management should be implemented with specific records that relate to the diagnostic plan and to the method by which data on components materials were obtained, as well as indicators relating to the confidence rating of the data.

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