Understanding the Level of Development (LOD) in Building Information Modeling (BIM)

Building Information Modeling (BIM) has transformed the way construction and facility management industries operate. One key aspect of BIM is the Level of Development (LOD), which is a crucial framework for defining the level of detail and accuracy in BIM models at various stages of the project lifecycle. This article provides a comprehensive overview of LOD and its significance in BIM projects.

What is LOD in BIM

Level of Development (LOD) in BIM refers to the level of detail and accuracy of a model at different stages of a project. It ranges from the basic conceptual design (LOD 100) to highly detailed as-built information (LOD 500). LOD ensures that each element of a BIM model evolves in detail and accuracy as the project progresses, helping stakeholders understand the reliability of the model data at each phase, from design through construction to facility management.

BIM Levels of Development (LOD)

BIM LOD defines the stages of a model's detail and accuracy, ranging from LOD 100, which represents basic conceptual design, to LOD 500, which includes fully detailed and as-built information. Each level corresponds to the progression of a project lifecycle, with increasing levels of detail in geometric information and reliability.

LOD 100: Design Concept

LOD 100, also known as the Design Concept level, involves the creation of a 3D model that provides fundamental information about the structure. At this stage, only conceptual models can be built, with defined parameters such as area, height, volume, location, and orientation. The Model Elements may be graphically represented in the Model with symbols or other generic representations. Data such as cost per square foot and HVAC tonnage can be derived from other Model Elements. LOD 100 elements are generally not geometric representations, and conclusions drawn from them should be considered approximations. Examples include data associated with other model elements or symbols indicating the presence of a component but not its particular location, size, or shape.

LOD 200: Schematic Design

LOD 200, or Schematic Design, includes a broad model with approximations of the size, form, position, and orientation of parts. The Model Element is a generic system item or assembly that has approximate quantities, size, shape, position, and orientation. At this LOD, elements serve as placeholders and may be identifiable as the parts they represent or as volumes used to reserve space.

LOD 300: Detailed Design

LOD 300, or Detailed Design, includes specific assemblies, exact quantities, sizes, shapes, locations, and orientations in accurate modeling and shop drawings. Non-geometric information can also be added to the model's components. Model Elements are graphically represented within the Model in terms of their amount, size, shape, location, and orientation. Measurements of the elements' amount, size, shape, location, and orientation can be made from the model without consulting non-modeled data. The element is precisely positioned in relation to the project origin, and the project origin is defined.

LOD 350: Construction Documentation

LOD 350 provides model details and elements that illustrate through images and written explanations how building elements interact with various systems and other building elements. The Model Element is a specific system object or assembly that is graphically depicted within the Model and is specified in terms of its amount, size, shape, placement, orientation, and interactions with other building systems. The model represents the components required for an element to coordinate with other surrounding or linked elements, such as supports and connections. Without using non-modeled information, measurements of the elements' amount, size, shape, location, and orientation can be made directly from the model.

LOD 400: Fabrication and Assembly

LOD 400 involves the representation of distinct assemblies that include fabrication, assembly, and detailing information as well as exact measurements for quantity, size, shape, placement, and orientation. The model pieces may have additional non-geometric information. The Model Element is graphically represented as a particular system object or assembly with information on fabrication, assembly, and installation, described in terms of its size, shape, position, quantity, and orientation. A LOD 400 element is modeled with enough accuracy and detail to allow for the production of the depicted component. Measurements of the elements' amount, size, shape, location, and orientation can be made directly from the model without consulting non-modeled data.

LOD 500: For Maintenance and Operations

LOD 500, or the As-Built level, involves modeling as-constructed assemblies with non-geometric information, true dimensions, shapes, locations, quantities, and orientations. In terms of size, form, placement, amount, and orientation, the Model Element is a field-verified representation. LOD 500 essentially refers to field verification and is just an as-built model. It does not represent a progression to a higher level of model element geometry or non-graphic information.

Conclusion

Understanding the Level of Development (LOD) is crucial for effective collaboration and communication across all project teams in the building information modeling process. By defining LOD, experts can describe how an element's shape and related information change over the course of the entire operation, ensuring that the BIM model evolves appropriately to meet the specific needs of each project phase. Proper LOD management leads to better decision-making, enhanced communication, and reduced project risks.