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Building Information Modelling (BIM) is a working method that makes it possible for several people to work collaboratively on a project. The individual pieces of information are uploaded to the CDE (Common Data Environment) by everyone involved in the project, so that they can be viewed by everyone. The decisive advantage of this method is that there are fewer collisions and errors in the planning of a building, which also reduces costs. Deadlines and budgets can therefore be adhered to easily and all simulations, that can stretch through the entire life cycle of the building, are also taken into account.
However, there are different types and variants of this working method. The two best known are Open BIM and Closed BIM.
Open BIM
Working in an Open BIM process is software-independent and can be used effortlessly with all individual specialist planning. The most commonly used file format is called IFC (Industry Foundation Class), which enables BIM data to be transferred regardless of the platform. The BCF (BIM Collaboration Format), in turn, is a file format that can be used to export collisions that were determined with the help of special coordination software. The various planners can thus import the BFC into their own system and get the errors displayed in the model.
The organisation behind this is buildingSMART, which is constantly developing the IFC. Due to the software-independent way of working, the open BIM variant offers the possibility of using the most suitable programme for each individual stakeholder. Different participants in a project, such as architects, building services planners or structural engineers, do not always use the same software for their models. The problem that can arise here is that programmes are not compatible with each other. Therefore, the neutral file format IFC is used. With the open BIM variant, these can be unified and merged into one model. This prevents expensive errors, such as collisions, and saves money in the long term.
Closed BIM
In contrast to Open BIM, Closed BIM uses software products from a single manufacturer and proprietary formats for data exchange. This means that the entire planning team must use the same software so that the native interfaces can be used. This software must therefore be coordinated with all the individual specialist plans that belong to a building. One advantage of the closed BIM method is the use of the native format. With the use of the native format, all information is transferred in the best possible way, which is why there are no interface problems with the software solutions.
However, if a project is planned with external actors, the closed BIM variant offers little flexibility, which can make collaboration more difficult.
Closed BIM or Open BIM – Which is Better?
Ultimately, it can be said that both variants have both advantages and disadvantages. It would be desirable to have holistic software that can serve all the ideal ideas of the individual specialist disciplines. Then the closed BIM method would probably already be the standard. In reality, however, it is often the case that a closed BIM method is started, which is then switched to an Open BIM variant by external project partners. So there is no real winner and loser here. We think – as long as BIM is used, it is a well-planned project!
If you want to dive deeper into the topic of BIM, check out our BIM Beginner Webinar!
