This BIM LOD (Level of Development) blog seeks to address the concept and understanding about LOD in AEC industry with clear guidance on its origin, definition and benefits.
What is LOD (Level of Development)?
The concept of “Level of Development” (LOD) aims to tackle the challenge that certain model elements progress at varying speeds throughout the design phase. LOD provides a way to describe the progressive growth of specific model elements from the idea stage to actualization. The metric of LOD allows for a more precise definition of project deliverables. As a widely accepted industry standard, it facilitates effective communication and collaboration among project stakeholders.
History of LOD?
The American Institute of Architects (AIA) developed the concept further in AIA Document E202 – 2008 Building Information Modeling Protocol Exhibit. It includes this definition:
“The Level(s) of Development (LOD) describes the level of completeness to which the model element is developed.”
It outlines a model element’s logical progression from the initial conceptual approximation stage to the final level of representation precision. The document establishes five distinct Levels of Development, ranging from 100 to 500. Each succeeding level is constructed on top of the previous one, resulting in a hierarchical structure.
The definition of LOD was amended in AIA draft document G202-2012 Building Information Modeling Protocol Form to the following:
“The Level of Development (LOD) describes the minimum dimensional, spatial, quantitative, qualitative, and other data included in a model element to support the authorized uses associated with such LOD.”
The BIMForum Level of Development specification authors recognized a necessity for a specific LOD that would adequately describe model components to enable coordination between various disciplines, such as clash detection and avoidance. Although the standards for this level surpass LOD 300, they are not as demanding as those for LOD 400. Consequently, the authors assigned the designation LOD 350 to this particular level.
What is BIM (Building Information Modeling)?
BIM (Building Information Modeling) is a digital representation of the physical and functional characteristics of a building or infrastructure project. BIM is a process that involves creating and managing digital models of a project’s design, construction, and operation, which can be used for decision-making throughout the project’s lifecycle.
BIM models typically contain 3D geometry, as well as data and information about the building’s components and systems, such as mechanical, electrical, plumbing, and structural systems. BIM models can also include data about cost, schedule, sustainability, and other important project information.
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BIM LOD (Level of Development)
BIM LOD is a measure of the completeness and accuracy of the information contained in a BIM model for a particular building element or system. The level of detail required for a BIM model can vary depending on the intended use of the model. The level of development required for a BIM model will depend on the stage of the project and the needs of the stakeholders involved.
There are typically five levels of development that are used to describe the level of completeness and detail of a BIM model.
The LOD 100, 200, 300, 400 and 500 definitions are produced by the AIA (The American Institute of Architects) and LOD 350 was developed by the BIMForum working group.
LOD 100: Conceptual
The model element may be graphically represented in the model with a symbol or generic representation, but does not satisfy the requirements for LOD 200. Information related to the model element (i.e. cost per square meter, etc.) can be derived from other model elements.
LOD 200: Approximate Geometry
The model element is graphically represented in the model as a generic system, object or assembly with approximate quantities, size, shape, location, and orientation.
Non graphic information may also be attached to the model element.
LOD 300: Precise Geometry
The model element is graphically represented in the model as a specific system, object, or assembly accurate in terms of quantity, size, shape, location, and orientation.
Non graphic information may also be attached to the model element.
LOD 350: Connection Details
The model element is graphically represented within the model as a specific system, object, or assembly in terms of quantity, size, shape, location, orientation, and interfaces with other building systems. Non-graphic information may also be attached to the model element.
LOD 400: Fabrication
The model element is graphically represented in the model as a specific system, object, or assembly accurate in terms of quantity, size, shape, location, and orientation with detailing, fabrication, assembly and installation information.
Non graphic information may also be attached to the model element.
LOD 500: As-built
The model element is field verified representation accurate in terms of size, shape, location, quantity, and orientation.
Benefits of LOD (Level of Development)
There are several benefits of LOD (Level of Development) in construction and design projects, including:1
1) Standardization: LOD standards created by AIA and BIMForums provides a common understanding that helps to improve communication and collaboration among project stakeholders.
2) Clarity: It provide clarity for the level of information required at the different design stages that helps to avoid misunderstandings and confusion.
3) Improved Coordination: LOD helps to improve coordination among different disciplines by specifying the level of detail required to facilitate clash detection and other coordination tasks.
4) Early Issue Identification: By defining the expected level of detail and accuracy at each stage, LOD can help to identify potential issues early on in the design and construction process.
5) Improved Quality: By specifying the expected level of detail and accuracy at each stage, LOD helps to improve the quality of the project deliverables.
6) Reduced Costs: By identifying potential issues early on in the process, LOD can help to reduce the cost of rework and other remedial measures.
7) Better Decision-making: By providing a clear framework for project delivery, LOD helps project stakeholders to make better decisions.
Conclusion
Main aim of BIM based LOD is to establish a convenient decision-making method during the early design stages. Investing more time in design stage and utilize LOD and its requirements consistently, would enhance the level of information and detail in BIM Objects. In conclusion BIM based LOD is essential for successful project delivery. It provides a standardized approach to design and construction, facilitates collaboration and communication among project stakeholders, and helps identify and address potential issues early on in the process.
References
- NATSPEC_Documents/NATSPEC_BIM_LOD_Paper_131115
- BIMForum – LOD Specification for Building Information Models
- American Institute of Architects, AIA Documents – Building Information Modeling Protocol
