EN

A confusing guideline?

LOD

LOD: a confusing guideline?

The LOD, or Level of Development, is often a source of confusion in BIM projects.

In most BIM protocols you will find the desired LOD level during the project and upon completion of the as-built model. However, it is often unclear what exactly is meant by an LOD. Because of this, there is often a subsequent discussion about what should and should not be stored in the BIM model.

Information management
The term LOD has come over from the United States, along with the BIM concept. The term is often interpreted as Level of Detail, but originally stood for Level of Development. It is a method to determine the amount of information in a model. The higher the LOD level, the more information and the more specific this information is. This includes not only the graphics but also the parametric alphanumeric data.

Construction phases
The term LOD is followed by a number, ranging from LOD 100 (sketch), LOD 200 (preliminary design), LOD 300 (final design), and LOD 400 (manufacturing drawings) to LOD 500 (as-built model). Since the implementation-ready design falls somewhere between the final design and manufacturing drawings in terms of level, recently we've seen the emergence of an intermediate level in BIM protocols: LOD 350. In that sense, the LOD level really is nothing more than another name for the traditional design, construction, and management phases, meant to say something about the type and amount of information that should be recorded in this regard.

Confusion
The term is diffuse in this latter area. Moreover, the kind of information that is expected at a certain level is different for each discipline (building, construction, and installation). In ISSO publication 109 (Working in BIM), the term LOD is accompanied by a sample itemized list per level. This is an illustration of how you could determine what information is expected at any moment in a BIM protocol. In the BIM protocol, it's often the case that something is only said about the number, but the information meant by it is omitted. This creates confusion.

Collaboration
The BIM model is not an end in itself but a means to manage, analyze, and share information. Information that helps to translate an idea into reality together, in order to realize and maintain a building. It should not be a fill-in-the-blanks exercise of (infinite) parameters. Instead of naming or reaching an abstract number, it is more advisable to clarify the information that really matters in advance. For your process, for the collaborative partners, and for the following processes during the realization and the life cycle of a building. An LOD number can be a guideline for this, but we can only work together if we really know what we expect from each other.