Many times we hear the term BIM. But what does this mean? When an owner asks if the project is going to be done in BIM, what is he really expecting? The AIA has a document, E202-2008 “Building Information Modeling Protocol Exhibit”, which provides a standard outline for the use of BIM information by a project team. By using this document, a project team can define and assign responsibility to areas of work like coordination and conflicts, model ownership and model management. The document also outlines Level of Development (LOD) categories as follows:
The model has overall building massing. The model may be analyzed with the “generalized performance criteria assigned to the model elements.” This level is typically used by architects to provide owner with conceptual feel for the building or provide rendering of key spaces.
Model elements are “generalized systems with approximate quantities, size, shape, location and orientation. The model may be analyzed for performance of selected systems by application of generalized performance criteria.” Basic levels of clash detection would start to be addressed.
Model elements are “suitable for the generation of traditional construction documents and shop drawings. The model may be analyzed for performance of selected systems for specific performance criteria.” Critical areas would be coordinated for clash detection.
“Model elements are modeled as specific assemblies that are accurate in terms of size, shape, location, quantity, and orientation with complete fabrication, assembly and detailing information.” Typically this is outside the scope of work for an architect or engineer, but the model is expanded by the trade contractors to purchase materials or generate shop drawings.
“Model elements are modeled as constructed assemblies actual and accurate in terms of size, shape, location, quantity, and orientation.” This will provide As-Built conditions and could be used for facility maintenance and operations.
Any of these LOD categories may be achieved according to what the intended end use of the model may be. A clear understanding of an owner’s BIM expectations at the beginning of a project will help direct the project team to a successful delivery.