The first thing to consider is the degree of BIM you wish to implement; below are some key terms related to levels of BIM to get you started:
- 3D BIM uses three-dimensional, geometric models.
- 4D BIM adds time into the equation (project phasing, construction schedules etc).
- 5D BIM adds cost simulation (resources, materials etc).
- 6D BIM all 3D elements are linked with data to provide a Facilities Management (FM) infrastructure for the building owner/occupier.
Terminology: Levels and LODs
The next aspect to consider is the technology used in the project:
- Level 0 BIM uses unmanaged, 2D drawings (paper or CAD).
- Level 1 BIM uses a managed 2D or 3D CAD environment with collaborative standards and a common data set.
- Level 2 BIM: is a managed 3D environment that uses a range of BIM tools to coordinate the data (This is where 4D and 5D BIM come into the picture).
- Level 3 BIM: You can only really achieve this level when the project is truly collaborative via a web-service and makes best use of 4D, 5D and 6D BIM.
3D civil engineering model
Laser scan and 3D Revit model created to engineering tolerances of Heath Town footbridge, as part of the council’s residential regeneration programmeRead case study
The final piece of the puzzle is to agree the Model Progression Specification (MPS) with the project supply chain. This ensures that the right Level Of Development (LOD) is achieved as the project takes shape. The result is that everybody knows what they are going to receive downstream and that no excess detail is produced too early on (this has a major cost impact).
The industry standard terminology for the MPS is LOD Spec and the following descriptions apply:
- LOD 100: Rough size and massing of the building/elements.
- LOD 200: Approximate size, shape and location of the building/elements.
- LOD 300: Accurate size, shape and location of the building/elements.
- LOD 400: Elements modelled as specific assemblies with all fabrication and detail data attached.
- LOD 500: Elements modelled as constructed assemblies with actual shape, size data etc.
So there you have it, a highly distilled version of the core terminology required if you are getting started with BIM.