What is BIM Model Accuracy? An Introduction to LOD
I’ve discussed BIM model accuracy before, but since many newcomers are now entering the BIM field and asking questions about model accuracy, I’d like to provide a brief overview here.
One frequently mentioned term in BIM technology is LOD, which stands for Level of Detail or Level of Development. It is often translated as “level of detail,” “degree of detail,” or “degree of development.” This concept originates from the American Institute of Architects (AIA) document E202, which defines the expected “level of completeness” at various stages of the building lifecycle. The document outlines five levels of development (LOD):
LOD 100: Represents the building in a very basic form, showing overall area, height, volume, position, orientation, and other general information through 3D models or other data formats.
LOD 200: Model elements represent generic systems or assemblies with approximate quantities, sizes, shapes, positions, and orientations. Non-geometric attribute information may also be included.
LOD 300: Model components are specific assemblies with accurate information about quantity, size, shape, position, and orientation. Non-geometric attributes can also be integrated into the model.
LOD 400: Model components are detailed assemblies with precise data on quantity, size, shape, position, orientation, and all necessary information for fabrication, assembly, and construction. Non-geometric attributes are also incorporated.
LOD 500: Represents completed assemblies that reflect the actual constructed conditions, including actual quantity, size, shape, position, and orientation. Non-geometric attributes are also part of the model.
To relate these LOD levels to traditional engineering drawings, the following equivalences can be drawn:
LOD 100 corresponds to a conceptual design diagram.
LOD 200 aligns with a preliminary design drawing.
LOD 300 matches detailed design drawings.
LOD 400 corresponds to construction drawings.
LOD 500 equates to as-built drawings.
In essence, as a project progresses through its lifecycle, the development and detail of model components become increasingly complete and refined. This means the level of detail defined by LOD essentially governs the development stage of the drawings.
That concludes the introduction to What is BIM Model Accuracy? An Introduction to LOD. I hope this helps everyone better understand the topic!
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