LOD: An Essential but Often Misunderstood Concept
LOD (Level of Development, Level of Detail, or Level of Definition depending on the framework) is a fundamental BIM concept that defines the degree of reliability and precision of elements in the digital model at each project phase. Understanding LOD is essential for establishing effective exchanges between stakeholders.
The Different LOD Levels
The American standard AIA (American Institute of Architects) defines an LOD scale from 100 to 500. LOD 100 represents a conceptual element (generic volume), LOD 200 a preliminary design element, LOD 300 a detailed design element, LOD 350 a coordinated element, LOD 400 a fabrication-ready element, and LOD 500 an as-built element.
LOD vs LOG vs LOI
In the British framework (PAS 1192 / ISO 19650), LOG (Level of Geometry) concerns the graphical representation, while LOI (Level of Information) defines the associated alphanumeric data. The combination LOG + LOI gives the LOD (Level of Definition). This distinction allows for a more refined specification of BIM requirements.
Specifying the right LOD level for each phase and each use avoids both over-modeling (wasted time) and under-modeling (insufficient information for intended uses).
Practical Application in Morocco
At Continuum BIM, we adapt LOD requirements to the Moroccan and African context. We draft BIM Execution Plans (BEP) that clearly define the expected levels of development at each project milestone, ensuring a shared understanding among all stakeholders.