Level of Development : Will a new standard bring clarity to BIM model detail
In 2008, the American Institute of Architects released its first BIM contract document—AIA E202 Building Information Modeling Protocol Exhibit—which outlined five “levels of development” (LOD 100-500) for defining the amount of detail in a particular BIM model. E202 provided basic definitions of each LOD but left a lot open to interpretation.
The E202 was a huge first step in that it provided the first viable vehicle for defining a BIM model at the element level and enabling downstream users to rely on it,” says James Bedrick, FAIA, LEED AP, Founder and Principal of AEC Process Engineering (www.aecpe.com). “Practitioners found, though, that the LOD definitions were being interpreted differently, and that there was a need for more clarity. What does LOD 200 specifically mean, for example, for a door?
None of the LODs offered a graphical representation of what a model at that level would look like or detailed instructions for how to use models in each LOD for a variety of disciplines. The document, which the AIA has since updated and published as the AIA G202-2013 Project Building Information Modeling Protocol Form (June 2013), had no specific rules or requirements for exactly what’s in a model at each level. As a result, design firms, general contractors, and subcontractors have no idea exactly what they would be handing off or receiving by way of the BIM model.
A new standard promises to lend much-needed clarity to the BIM model detail issue. BIMForum, a multidisciplinary group of BIM users, has released its first BIM deliverable document, the Level of Development Specification. Working under an agreement with the AIA, the BIMForum LOD committee added context and meaning to the AIA G202-2013 definitions for levels 100, 200, 300, and 400, and added a new level (350) for trade coordination. It enables Building Teams to specify and articulate with a high level of clarity the content and reliability of BIM models at various stages, allowing downstream users to clearly understand the usability and limitations of models they are receiving. It’s organized by CSI Uniformat 2010, but expands the subclasses to Level 4 to provide a detailed breakdown and more clarity to the element definitions.
The key to being able to break out of this quasi-definition cycle is collaboration,” says James Vandezande, AIA, Principal at HOK (www.hok.com), who served on BIMForum’s LOD committee. “It’s a stepping stone to get from document deliverables to model deliverables. This particular stepping stone is the tool that levels expectations between different stakeholders and provides an apples-to-apples comparison.
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