Why BIM is not a 3D model
For such a prolific acronym, there is still confusion about “BIM” and its part within the digitalisation of the construction industry.
The acronym “Building Information Modelling” can lead to two misleading interpretations:
- The first is that this BIM is only relevant to buildings
- The second is that it is all about some sort of visual model
It is common to hear people in the industry talk about a “BIM model” to mean a 3D graphical representation of the design. We have also heard people talk about BIM as “everything on a project”, which is also not a helpful description.
One should think of BIM as the adoption of standardised processes to enable “Better Information Management”. This means focusing on the specification, delivery, exchange, and use of all types of information relating to the asset throughout its lifecycle.
What is BIM officially?
The standards surrounding BIM are constantly evolving. The industry strives to make it as inclusive as possible across sectors and countries. The most recent iteration of this suite of standards is the internationally recognised ISO 19650. This officially documents the “BIM” approach to collaborative information management processes, against which companies can be externally audited.
BIM is about how the supply chain collaborates and shares information. By following BIM processes, you’re able to generate:
- well-structured data to enable functionality like clash reporting
- construction sequencing in the 3D model (4D)
- cost estimates from a 3D model (5D)
Parts of the standard are general: generating information requirements, execution planning, developing the information and finally, its acceptance. In other aspects, it is more detailed, such as the UK edition’s (BS EN ISO 19650) description of document numbering and revision processes.
In most cases, when a project’s standards specify that it is adopting BIM, project documentation and processes to a lesser or greater degree take the ISO standard and build project specific information requirements around these concepts. Clients may, and should, ask for an audit to be conducted on their supply chain to ensure that it is adhering to the standards.
What does it mean for a project to be using BIM?
ISO 19650 identifies some key concepts such as a CDE (Common Data Environment), PIM (Project Information Model) and AIM (Asset Information Model). Understanding this terminology the concepts it represents is essential to ensure that the project is adhering to the standards and generates the necessary processes.
The standards identify 3 types of information:
- geometrical information – spatial and dimensional information captured in a 3D model or on 2D drawings
- non-graphical (or alpha-numeric) data – attributes about an asset such as a material type
- documentation – such as reports and specifications
The idea is to identify the information requirements upfront and then gather the necessary information progressively during the execution of the project. At the end of the project, this “PIM” is then handed over to the project owner, becoming responsible for maintaining the “AIM”. Teams are expected to use “CDEs” to aid the transfer of information to the various parties involved in the project.
As the information is directly related to a particular set of assets, a project must ensure all parties adopt BIM principles and adhere to the project’s procedures. Without this agreement in place, the transfer of information becomes heavy. When each organisation chooses its way of working, this leads to misunderstandings and delays in other organisations’ workflows.
If you want to know more about the UK BIM framework, visit ukbimframework.org.
