Level of Development (LOD) defines the level of completeness to which model components or elements are developed. The LOD terminology is derived from the American Institute of Architects Document E203-2012, Building Information Modelling Protocol Exhibit.
These progressive levels help define consistent expectations of the content make-up through the building lifecycle. There are five defined LOD descriptions as outlined in the AIA modelling protocol.
There is a common misinterpretation that LOD terminology can be used to describe an entire model, or a project phase, when in fact they describe element development. This means you can have instances of LOD 100 to 400 model elements represented in a project model at any particular time relevant to the stage of delivery of that element.
|Overall building massing indicative of area, height, volume, location, and orientation may be modeled in 3D or represented by other data. When elements at LOD 100 are combined we see the equivalent of a conceptual design, consisting of overall building massing designed to perform whole building type analysis including daylight, wind, noise, volume, building orientation, costs per square meter, tonnage of HVAC etc.|
|Model elements are modeled as generalised systems or assemblies with approximate quantities, size, shape, location and orientation. Non-geometric information may also be attached to model elements. Similar to schematic design or design development, a model with LOD 200 elements would consist of generalised systems including approximate quantities, size, shape, location and orientation. A model of LOD 200 elements can be typically used for analysis of defined systems and general performance objectives.|
|Model elements are modeled as specific assemblies accurate in terms of quantity, size, shape, location and orientation. Non-geometric information may also be attached to model elements.LOD 300 elements are considered equivalent to traditional construction documents and shop drawings. LOD 300 elements can be combined and used for estimating as well as construction coordination, clash detection, scheduling, and visualisation.|
|The Model Element is graphically represented within the Model as a specific system, object, or assembly in terms of quantity, size, shape, orientation, and interfaces with other building systems. Non-graphic information may also be attached to the Model Element.|
|Model elements are modeled as specific assemblies accurate in terms of quantity, size, shape, location and orientation, with complete fabrication, assembly, and detailing information. Non-geometric information may also be attached to model elements.This level of development is considered to be suitable for fabrication and assembly. LOD 400 elements are most likely to be used by specialty trade contractors and fabricators.|
|Model elements are modeled as constructed assemblies, for example accurate in terms of quantity, size, shape, location and orientation. Non-geometric information may also be attached to model elements.The final level of development represents data as constructed including as-built conditions. LOD 500 elements will include completed parameters and attributes detailed in the owners BIM deliverable specification.|
Taking a light fixture as an example, its different LOD definitions would be:
- 100 Cost/sq.m attached to floor slabs.
- 200 Light fixture, generic/approximate size/shape/location.
- 300 600x1200mm troffer, specific size/shape/location.
- 350 Lightolier DPA2G12LS232, specific size/shape/location.
- 400 As 350, plus special mounting details, as in a decorative soffit.