Fundamental LOD Definitions

The Level of Development (LOD) Specification is a reference that enables practitioners in the AEC Industry to specify and articulate with a high degree of clarity the content and reliability of Building Information Models (BIMs) at various stages in the design and construction process. The Specification is a detailed interpretation of the LOD schema developed by the American Institute of Architects (AIA) for its E202- 2009 BIM and Digital Data Exhibit and updated for its G202-2013 Project BIM Protocol Form1, defining and illustrating2 characteristics of model elements of different building systems at different Levels of Development, organized according to CSI Uniformat 20103. Its intent is to help explain the LOD framework and standardize its use so that it becomes more useful as a communication tool.
This Specification does not replace a project BIM Execution Plan or BIMXP, but rather is intended to be used in conjunction with such a plan, providing a means of defining models for specific information exchanges, milestones in a design work plan, and deliverables for specific functions.

LOD 100
The Model Element may be graphically represented in the Model with a symbol or other generic representation, but does not satisfy the requirements for LOD 200. Information related to the Model Element (i.e. cost per square foot, tonnage of HVAC, etc.) can be derived from other Model Elements.
Interpretation: LOD 100 elements are not geometric representations. Examples are information attached to other model
elements or symbols showing the existence of a component but not its shape, size, or precise location. Any information derived from LOD 100 elements must be considered approximate.

LOD 200
The Model Element is graphically represented within the Model as a generic system, object, or assembly with approximate quantities, size, shape, location, and orientation. Non-graphic information may also be attached to the Model Element.
Interpretation: At this LOD elements are generic placeholders. They may be recognizable as the components they represent, or they may be volumes for space reservation. Any information derived from LOD 200 elements must be considered approximate.

LOD 300
The Model Element is graphically represented within the Model as a specific system, object or assembly in terms of quantity, size, shape, location, and orientation. Non-graphic information may also be attached to the Model Element.
Interpretation: The quantity, size, shape, location, and orientation of the element as designed can be measured directly from
the model without referring to non-modeled information such as notes or dimension call-outs.

LOD 350
The Model Element is graphically represented within the Model as a specific system, object, or assembly in terms of quantity, size, shape, location, orientation, and interfaces with other building systems. Non-graphic information may also be attached to the Model Element.
Interpretation: Parts necessary for coordination of the element with nearby or attached elements are modeled. These parts
will include such items as supports and connections. The quantity, size, shape, location, and orientation of the element as designed can be measured directly from the model without referring to non-modeled information such as notes or dimension call-outs.

LOD 400
The Model Element is graphically represented within the Model as a specific system, object or assembly in terms of size, shape,
location, quantity, and orientation with detailing, fabrication, assembly, and installation information. Non-graphic information may also be attached to the Model Element.
Interpretation: An LOD 400 element is modeled at sufficient detail and accuracy for fabrication of the represented
component. The quantity, size, shape, location, and orientation of the element as designed can be measured directly from the model without referring to non-modeled information such as notes or dimension call-outs.

LOD 500
The Model Element is a field verified representation in terms of size, shape, location, quantity, and orientation. Non-graphic information may also be attached to the Model Elements.
Interpretation: Look here if only you have too much money for your project.

Example – Light Fixture:
– 100 cost/sf attached to floor slabs
– 200 light fixture, generic/approximate size/shape/location
– 300 Design specified 2×4 troffer, specific size/shape/location
– 350 Actual model, Lightolier DPA2G12LS232, specific size/shape/location
– 400 As 350, plus special mounting details, as in a decorative soffit

Level of Development vs. Level of Detail

LOD is sometimes interpreted as Level of Detail rather than Level of Development. This Specification uses the concept of Level of Development. There are important differences.
Level of Detail is essentially how much detail is included in the model element. Level of Development is the degree to which the
element’s geometry and attached information has been thought through – the degree to which project team members may rely on the information when using the model.
In essence, Level of Detail can be thought of as input to the element, while Level of Development is reliable output.