Have you ever wondered what LOD is? Well, wonder no more! We will now explain in detail this concept and the differences between each of its levels.
After reading the article, 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 “Level of Detail” or “Level of Development” is an indicator that tells us the state of the information that the BIM model should have at a particular phase of a project. It helps you identify and understand the level of data, parameters, and geometry that a BIM model contains.
One way of making this level of detail evident can be from the visual aspect of the 3D model. But not all the parameters are visible by just watching the virtual model; it may be necessary to interact with it to know the depth of the level of detail.
Which are the levels of detail?
These are the most accepted LOD levels:
LOD 100: This is a level of physical appearance, visual proposal, or conceptual design, equivalent to 20% of the total amount of information possible. In other words, a “Concept or even Schematic Design model”.
LOD 200: Considered a basic or schematic level that includes dimensional parameterized information, equivalent to 40% of the total amount of information possible. In other words, a Design Development model.
LOD 300: Besides their geometric dimensions, at this level, the elements already contain certain functions. It corresponds to 60% of the total amount of information possible. In other words, a Detailed Design model appropriate for Construction Drawings creation.
LOD 350: it’s a model that adds certain elements (i.e: Hangers and Supports, etc) to the LOD 300 model to be more accurate when doing 3D Preconstruction Coordination, but it is not a Fabric level model.
LOD 400: At this level, the elements already have the information of a LOD 300 plus the parameters and precise geometry of a specific product, its model, manufacturer, cost, etc., and it is already contemplated at a project level, equivalent to 80% of the total amount of information possible. This would be a Fabrication level Model.
LOD 500: This level is known as “AS-BUILT”. In other words, it refers to a level in which the model is a close replica of the already built building. This LOD generally contains 100% of the necessary information for Operations. Also, LOD 500 is many times regarded as an FM model. Geometry precision is not as important in an LOD 500 as it is on an LOD 400. At this stage, FM data is more relevant than geometry.
So, higher LOD = higher “detail”?
The common belief is that the higher the LOD, the more detailed, the more features will be described in the elements that are part of a BIM model.
But this may not always be the case. Many times, you may want to customize LODs to fulfill the actual purpose of the BIM process: for instance, a hybrid between LOD350 with LOD400, when only certain components are -prefabricated. LOD 500 is, in theory, an incredibly detailed, data-rich BIM Model to be handed over to the owner for operations. Our definition of LOD 500 varies from the theoretical. We have learned through experience that an LOD 500 model may even have to be simplified on its geometry to be lighter and only contain specific data that the Facility Manager requires. So, when creating an LOD 500 model, you may turn off “hangers layers”, but you may add Instruments for example that may have not been relevant for Coordination, but are important for operations.
So then, which things should be taken into account when choosing the LOD?
- Make sure that systems are created as per operational functions in the model.
- That all critical assets are represented, even if not relevant for the BIM coordination process
- Turn off elements that make the model heavy and don’t add value .
Sometimes each LOD may not need certain features. It will have a higher level of detail than the previous LOD, but not all elements must always be at every level.
This will always be set and defined in the distinct phases of a BIM project as a different LOD will be necessary and will evolve according to the BIM goals and needs of the final client.
Finally, it is crucial to approach the BIM modeling based on the real needs of the client and their project. We believe this to be the best way to define the necessary LOD to achieve goals with the highest speed, precision, and financial benefits.
If you want to keep reading about LOD, we highly recommend you one of our previous articles: LOD downgrade? written by Axel Kruger, CEO of ENG.
For more information, contact us!
Call us: (949) 340-6924
*LOD definitions and specifications from BIMForum (https://bimforum.org/lod/)