What is the LOD of a BIM model?

5 / 4 / 2018

Level of Development (LOD) = Level of Development (ND)

In the BIM concept, the model is built in a virtual space , shared between several professionals, and is developed through graphic and non-graphic information, precisely linked and clearly structured.

When starting projects using the BIM methodology, it is necessary to identify the objective for the model, as this will define the level of definition of the data that will feed it. These levels differ in the amount of data that will be available at each stage of the project. And it is very important that everyone involved is aware of this need, as these levels will define the final product. It is from this information that a detailed project will be obtained, well resolved between all disciplines, in addition to this information being used to analyze the model, even with regard to planning, budgeting and maintenance of the construction.

The LOD of a model is characterized by the combination of the Level of Model Information (LMI) and the Level of Model Detail (LMD).

LMI – is the amount of non-graphic information developed at a given stage of the project.

LMD – is the amount of graphic information developed at a given stage of the project.

It should be noted, however, that there is no standardized definition of these levels. Analyzing reference publications from various countries, it can be seen that the classifications can vary greatly.

Reference Comparisons

In the table below you can see the classifications of the main references:

PAS 1192-2 and SC-Caderno BIM : Cover the entire project management process, from the information gathering study to post-construction.

AIA-G202-2013 and the BIM Forum: Consider information from the volumetric study to the as-built.

PAS 1192-2 considers a level (LOD 7) only for post-construction. SC-Caderno BIM considers ND 500 for as-built and post-construction. The others do not consider post-construction information in the model.

The BIM Forum follows AIA-G202-2013 as a reference , but suggests adding LOD 350, which defines a level for the coordination of all disciplines involved. Consequently, SC-Caderno BIM follows the BIM Forum as a reference and adopts the suggestion.

Only the SC-Caderno BIM links the project development levels to the project stages (feasibility study, preliminary study, preliminary project, legal, basic, executive).

Conclusion

In this way, it can be seen that the classifications vary, but always in accordance with definitions based on variations in the graphic and non-graphic information of the model.

Ultimately, LOD defines only one concept. And this classification may occur in whatever way is necessary for the type of project that will be developed in BIM. Therefore, the same company may design models with different LOD classifications. Furthermore, in the same model, disciplines may present different LODs, or even, in the same discipline, each component may have a different LOD. Everything will be defined according to the need for graphic representation and non-graphic information to be inserted in the model.

To facilitate this understanding, observe the diagram below:

We have a wall and a window frame that are initially presented in LOD 200. As the information is inserted, we can observe the graphical evolution and verify the increase in data that can be used later. It is easy to see that even if a wall is very detailed, with layers of materials, the generic window frames can be maintained, with the minimum of information, practically only to identify the element and the dimensions.

It is concluded that the LOD must be associated with the component, according to the need for graphic and non-graphic information and that it should not be limited to the model, nor even to the design stage. The level must be relative to what you intend to deliver, for example, you can have an executive project in LOD 300/350.

When necessary, a level can also be divided into categories, categorizing the information, which can help monitor development and identify the component level. Hypothetically, a component could be at level 200 and have the goal of reaching level 300, and for monitoring development, level 200 could be divided into, for example, 210, 220, 230 and so on until it reaches the desired level.

Source: https://biminformation.blog/2017/03/16/lodmodelobim/