Have you ever wondered what LOD is? This article explains the concept and the differences among the LOD levels. You will learn the main indicators and differences between LOD 100, LOD 200, LOD 300, LOD 400, and LOD 500.
What is LOD?
In a few words, LOD, or “Level of Detail” / “Level of Development,” indicates the state of the information that the BIM model should have at a particular project phase. It helps you identify and understand the level of data, parameters, and geometry that a BIM Model contains.
One way to understand the level of detail is through the visual representation of the 3D model. However, not all parameters are visible by simply viewing the virtual model. You may need to interact with it to understand the full depth of detail.
Which are the levels of detail?
These are the most accepted LOD levels:
LOD 100: This level represents physical appearance, visual proposal, or conceptual design, equivalent to 20% of the total possible information. In other words, it is a concept or schematic design model.
LOD 200: This is a basic or schematic level that includes dimensional, parameterized information, equivalent to 40% of the total possible information. In other words, it is a design development model.
LOD 300: At this level, elements include geometric dimensions and certain functions. It corresponds to 60% of the total possible information. In other words, it is a detailed design model suitable for the creation of construction drawings.
LOD 350: This model adds certain elements, such as hangers and supports, to the LOD 300 model to improve accuracy during 3D preconstruction coordination. However, it is not a fabrication-level model.
LOD 400: At this level, elements include the information from LOD 300, plus the parameters and precise geometry of a specific product, including model, manufacturer, cost, and other project-level details. It is equivalent to 80% of the total possible information. This is a fabrication-level model.
LOD 500: This level is known as “as-built.” In other words, the model closely represents the completed building. This LOD generally contains 100% of the necessary information for operations. LOD 500 is also often regarded as a Facility Managed model. Geometry precision is not as important in LOD 500 as it is in LOD 400. At this stage, FM data becomes more relevant than geometry.
So, higher LOD = higher “detail”?
The common belief is that the higher the LOD, the more detail and features each BIM model element contains. However, this is not always the case.
In many cases, you may need to customize LODs to fit the actual purpose of the BIM process. For example, a project may require a hybrid between LOD 350 and LOD 400 when only certain components are prefabricated. In theory, LOD 500 is a highly detailed, data-rich BIM model handed over to the owner for operations.
Our definition of LOD 500 differs from the theoretical definition. We have learned through experience that an LOD 500 model may need simplified geometry to remain lighter and include only the specific data the Facility Manager requires.
What to Consider When Choosing the Right LOD
When choosing the right LOD, it is important to define what the model needs to support at each project phase.
- Make sure that systems are created as per operational functions in the model.
- Ensure that all critical assets are represented, even if not relevant for the BIM coordination process.
- Turn off elements that make the model heavy and do not add value.
Each LOD may not need the same features. A higher LOD may include more detail than the previous level, but not every element needs to appear at every level. The required LOD should always be defined during the different phases of a BIM project. It will evolve according to the BIM goals and the needs of the final client.
Conclusion
Finally, BIM modeling should always be based on the real needs of the client and the project. This is the best way to define the right LOD, support project goals, improve precision, and avoid unnecessary modeling effort.
Need help defining the right LOD for your BIM project? ENG can help you align model details, coordination requirements, and project goals so your BIM process delivers value without adding unnecessary complexity. Contact us to discuss your project.
