BIM levels of development

Building Information Modelling (BIM) is a very broad term that describes the process for specifying, creating, and managing digital information about a built asset such as a building, bridge, highway or tunnel.

BIM levels of development (LOD) refers to the degree of accuracy, intricacy or granularity of the model or design. In general these LODs include LOD 100, LOD 200, LOD 300, LOD 400 and LOD 500.

BIM LOD was first introduced by the American Institute of Architects (AIA) in 2008, it defined five levels of development to describe the level of detailing appropriate for early to later stages of a project. In the UK a similar approach might be considered as relating the BIM model to the stages of the RIBA plan of work. Fore further information visit the page overlays to the RIBA plan of work, in particular the BIM overlay.

Fundamentally, the purpose of BIM is to ensure that appropriate information is created in a suitable format at the right time so that better decisions can be made throughout the design, construction and operation of built assets. It is not about creating a 3D model on its own or an add-on to the model, it is a fundamentally different way of running a project from the early stages through to occupation, maximising digital capabilities. The amount of data associated with the model is referred to as the dimension or sometimes level when referring to complexity or capabilities.

ISO 19650:2019 defines BIM as the: 'Use of a shared digital representation of a built asset to facilitate design, constructionand operation processes to form a reliable basis for decisions.'

The BIM levels of development (BIM LOD) are:

• LOD 100 describes concept design stages, essentially the equivalent of hand-sketched or, symbolic digital 2Drepresentations of the design-build project.
• LOD 200 describes the schematic design stage where a partially defined idea with approximate project sizing, form and building elements are established.
• LOD 300 describes the detail stage of a project whereby a 3D digital model represents the building in terms of architectural design and engineering drawings with more exact localised dimensions and elements.
• LOD 350 is essentially a halfway stage between detailing and fabrication, a point where tools suich as clash detectionare employed to ensure individual elements are sychronised into the whole, resolving co-ordination issues and inconsistencies to produce a construction ready model.
• LOD 400 is the last stage of modelling before fabrication and assembly. The model must contain an accuraterepresentation of the elements, objects and thus building with finalised and defined elements, sizes, locations, connections, materials and so on.
• LOD 500 represents the as-built final model of the building with supplementary information such as installationprocesses, installation dates, comments on issues, notes for the users and so on. It is an important element of the process when considering concepts such as the golden thread of information or how the model might used to inform Building Management Systems (BMS) and assist facilities management team after handover. Further tools available via COBie or the Soft Landings process can assist in this.

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