The American Institute of Architects defines model depth in its standard G202-2013 BIM protocol format, which specifies the Level of Development (LOD). This standard divides model depth into five levels: LOD100, LOD200, LOD300, LOD400, and LOD500. Each level defines the minimum required content to meet the specified model depth.
Besides providing reference requirements for model depth, the standard includes a Model Element Table designed to help both modelers and users apply these LOD definitions by completing the table accordingly. However, the G202-2013 document does not provide sample completions of the table, nor does it offer detailed information requirements for components at each LOD level in engineering projects.
As a result, personnel or organizations wanting to use the LOD framework must define their own depth requirements for each component by filling out this table according to their standards. This approach allows the creation of an internal reference standard but may lead to inconsistencies between companies and misunderstandings during information exchange among project participants.
The definition of each LOD level in the G202-2013 standard differs from that in the BSI PAS1192-2:2013. Instead of aligning LOD with project stages, it is defined based on the model’s graphic detail and information integration, from low to high, specific to each component. Consequently, models created at different project phases may contain a mix of various LOD levels, ranging from LOD100 to LOD500.
Below are the definitions for each LOD level:
LOD100: Model elements are represented by symbols or other general indicators. Information at this level is approximate and may be derived from other model elements. It indicates existence but lacks precise shape, size, or location details.
LOD200: Model elements may appear as generic systems, assemblies, or groups with approximate quantities, sizes, shapes, positions, and orientations. Non-graphical information may also be included. Compared to LOD100, these form rough three-dimensional representations.
LOD300: Model elements are detailed systems, assemblies, or groups defined by accurate quantities, sizes, shapes, positions, and orientations. They can be directly measured from the model without needing additional non-graphical data, although such data may still be present.
LOD350: This level builds on LOD300 by adding parts that coordinate or connect with surrounding building systems or components. It serves as a transitional level between LOD300 and LOD400, reflecting the increased complexity of establishing relationships between model components.
LOD400: Model elements include detailed systems, assemblies, or groups with comprehensive descriptions, manufacturing, assembly, and installation information, alongside quantity, size, shape, position, and orientation details. Non-graphical information may still be present.
LOD500: Representing the highest level, model elements are verified through on-site measurements confirming quantities, sizes, shapes, positions, and orientations. Additional non-graphical data may be included. Since on-site verification is required, the specific details added to LOD400 elements can vary depending on the project, allowing for flexible adjustments to model depth.
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