[CAD Note]
BIM levels
Level 0 BIM
Unmanaged computer aided design (CAD) including 2D drawings, and text with paper-based or electronic exchange of information but without common standards and processes. Essentially this is a digital drawing board.
Level 1 BIM
Managed CAD, with the increasing introduction of spatial coordination, standardised structures and formats as it moves towards Level 2 BIM. This may include 2D information and 3D information such as visualisations or concept development models. Level 1 can be described as 'Lonely BIM' as models are not shared between project team members.
This typically comprises a mixture of 3D CAD for concept work, and 2D for drafting of statutory approval documentation and Production Information. CAD standards are managed to BS 1192:2007, and electronic sharing of data is carried out from a common data environment (CDE), often managed by the contractor. This is the level at which many organisations are currently operating, although there is no collaboration between different disciplines – each publishes and maintains its own data.
Level 2 BIM
Managed 3D environment with data attached, but created in separate discipline-based models. These separate models are assembled to form a federated model, but do not lose their identity or integrity. Data may include construction sequencing (4D) and cost (5D) information. This is sometimes referred to as 'pBIM' (proprietary BIM).
In the UK the Government Construction Strategy published in May 2011, stated that the '...Government will require fully collaborative 3D BIM (with all project and asset information, documentation and data being electronic) as a minimum by 2016'. This represents a minimum requirement for Level 2 BIM on centrally-procured public projects.
This is distinguished by collaborative working – all parties use their own 3D CAD models, but not necessarily working on a single, shared model. The collaboration comes in the form of how the information is exchanged between different parties – and is the crucial aspect of this level. Design information is shared through a common file format, which enables any organisation to be able to combine that data with their own in order to make a federated BIM model, and to carry out interrogative checks on it. Hence any CAD software that each party used must be capable of exporting to one of the common file formats such as IFC (Industry Foundation Class) or COBie (Construction Operations Building Information Exchange). This is the method of working that has been set as a minimum target by the UK government for all work on public-sector work, by 2016.
Level 3 BIM
A single collaborative, online, project model with construction sequencing (4D), cost (5D) and project lifecycle information (6D). This is sometimes referred to as 'iBIM' (integrated BIM) and is intended to deliver better business outcomes.
Level 4 BIM
Level 4 introduces the concepts of improved social outcomes and wellbeing.
https://www.designingbuildings.co.uk/wiki/BIM_maturity_levels
https://www.thenbs.com/knowledge/bim-levels-explained
