It is becoming more common for the Level of Development (LOD) to be specified on projects that require Building Information Modeling (BIM). Many times, the “LOD” term is thrown around and utilized without the specifier being familiar with what the term really means. As a result, confusion abounds and clients may say they want “a LOD 500 project”, although it does not really exist.
The AIA® Document E202™ – 2008 contract document is dedicated to defining the BIM requirements for a project and describes the LODs of 100, 200, 300, 400 and 500. Level of Development (often called Level of Detail) refers to the amount of graphical and non-graphical information that is put into a model element. That degree of development gets progressively more complex as you move from LOD 100 to LOD 500.
It is important to note that the LOD refers to Model Elements, and not the project. Model Elements are individual items, such as Revit families, ArchiCAD elements, and AutoCAD blocks. A different LOD can be assigned to each different category of model elements. This allows for the author of the E202 to determine how important they deem the LOD for each type of element. As an example, they may determine that it is very important for them to have more detail for doors than for cabinetry. It is also typical to specify a low LOD for items such as elevators which are provided as a packaged unit.
If a project is referenced as a specific LOD, that infers that everything in the model will be developed to that LOD. While that is likely what the person is desiring, the E202 document still needs developed so all model elements are specified as such and attention needs to paid as to whether it is really desired or even possible.
Referencing a project as a specific LOD also does not take into consideration the various stages of a project and what LOD is desired at each stage. If a project is referenced as a LOD 400, that could be considered at the end of construction or at the end of the design stage. Are all disciplines expected to be that LOD, or just specific disciplines?
Having a different LOD for different element categories is important in situations where the software just is not yet capable of providing a high degree of BIM capability. It is important to have a realistic expectation of the capabilities of the BIM software and not specify a LOD that is not practical at this point in time. Each project needs to have the LOD carefully and realistically considered based upon individual model elements.
Other articles I have written on the E202 explain aspects of it in further detail. These articles can be reviewed by selecting the E202 category on the sidebar of this blog.