What is LOD 500?
Level Of Development Explained
LOD 500 is a fun one. 😅
On a typical project we start with an idea, propose and coordinate with others, go build it and then operate and maintain everything for the life of the building.
The example below (from Trimble) shows a Building Information Model (BIM) progressing with more elements, more detail, and also maybe more maturity, reliability, accuracy, information – you get the idea. 😃
As we move from left to right it’s more more more:
The concept of LOD 100 through 400 can help us to define that project progression – however…
LOD 500 has been more difficult to define and understand – so much that the US BIM Forum states:
“The LOD Specification does not address LOD 500 since that LOD relates to field verification and is not an indication of progression to a higher level of geometry or information.”
Fixing an LOD Scale:
Since 2004 LOD has been seen by many as a fixed scale moving from LOD 100 through to LOD 500.
The natural interpretation, when moving to a higher LOD number, is that it calls for more elements, more detail, more accuracy, etc.
Unfortunately a fixed scale incorrectly suggests that LOD 500 is the maximum level of all aspects and requirements.
In practicality this is actually not the case and this misunderstanding of LOD has caused some costly miscommunication.
In reality, after construction, we do not create more elements/geometry/detail and we are not attaining a higher degree of accuracy than what was required to build from the model.
Compared to LOD 400, and with these points in mind, the image below maybe shows the practical extent of what LOD 500 could be?
The implication of LOD 500:
This departure from a linear progression may help to show why LOD 500 has been a challenge for our industry to agree on.
Unfortunately the use of just a simple fixed scale has led to one Californian construction team sharing:
“LOD 500 was specified [for the project] because the owner wanted information added to elements for FM – we wasted time modeling way too many elements that were not important for the owner”
What should LOD 500 be?
The BIM Uses for an LOD 500 model are usually (but not always) driven by an owner’s Facilities Management (FM) workflow.
For FM it is unlikely that as much geometry or accuracy is actually required and usually the owner is interested in fewer and different data/information.
So, maybe this is a closer interpretation of what LOD 500 should be?
Historically there has been a high potential for misunderstanding and severe implications when using LOD 500 as a linear scale.
Perhaps knowing that LOD 500 is actually a “field verified” or “as-built” model we may now be able to specify only what’s important at this stage.
Our team found that the BIM community wanted a more flexible way to define these model requirements.
Users asked for the flexibility to define:
- ELEMENTS: which elements that were actually required by the owner
- ACCURACY: the Level Of Accuracy (LOA) for a model based on it’s use
- INFORMATION: which information parameters were actually needed
- DETAIL: the required geometric detail
Here is an example where the user removes elements that are not required, adds specific information requirements for handover, adjusts the level of accuracy (LOA – as defined by the USIBD) required and also modifies the geometric requirements for HVAC Distribution Systems:
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