This is kind of a repost of an earlier Blog on understanding the Levels of Development.
BIM Level of Development as
outlined by the AIA. Even though it's American standards they have done a lot
of research on this subject so it's defiantly worth taking a look and modifying
it to your specific needs.
The reason I'll discuss
this subject is that as we use Revit more and more we at risk of Over Modeling our model. Over modeling
will reduce your efficiency of your workflow as well as the efficiency of your
model. We work hard to make Revit work for us but we are in danger of getting
sucked into the Void of Over Modeling....
Here is a brief explanation
of Level of Development (LOD):
Level of Development: Levels of Development (LOD) describe the
level of completeness to which a Model Element is developed.
How much we model at each
stage is broken down into 5 basic levels.
LOD 100 -
Conceptual Design and Master Planning, creating mass models for the concept stage. Volumes, height, location
and orientation, basic building analysis etc. This model can be quickly and
easily be analyzed for energy consumption to help make design changes and
approval for design options.
LOD 200 -
Schematic Design/Design Development. Developing the general assemblies, rough sizes and placement of rooms
etc. Here you have the general idea on the design but do not have the specific
information on exact wall assemblies or component types. This LOD is typically
the basis for the working drawings.
LOD 300 -
Working Drawings, Shop Drawings, construction documentation, building analysis, shop drawings etc. Not
everything needs to be modeled during this level of development, you can place
in your model placeholders which can be specified in the Spec documentation
outside of the Building model.
LOD 400 – Fabrication
and Assembly typically not achieved by the Designer or
Architect as this level of detail is typically required by fabricators, for
example manufacturers of RTU's would detail their components at this level for
fabrication of their components.
LOD 500 -
As Built Model, Maintenance and Operations, the final level of detail that represents the true building. Ideally
used for building operations and maintenance. Typically includes extensive
information within the model on each component, for example a light fixture may
have the wattage, warrantee information, the suppliers contact info, model
number etc…
Model Elements: Model Elements represent building
component, system or assemblies within a building or building site.
Model Element Author: The party responsible for developing the
content of the specific model. To the Level of Detail required by the
particular phase of the project.
Model User: this refers to any authorized individual or
company who may use the model. For example someone doing a quantity take off,
scheduling, analysis?
So... LOD... Level of Development
how does this affect the typical Revit User?
In the old 2D drafting days
we would draw lines to represent objects such as walls doors, windows roofs
etc... remember that? We use to draw two lines representing a complete (and
often complex) wall assembly. Often these lines didn't even represent the true
dimensions of the assembly either!
Drawings got done and
buildings still got built.! Amazing times.....
Now with BIM were adding
more information to our drawings by adding more information to our Building
Information Model. For the majority of us the end result is a set of documents
that someone can build from. Don't lose sight of that, we are in danger of Over
Modeling....
We get so wrapped up in
creating content and families for everything that sometimes we loose sight of
why we are creating this model in the first place. Remember your creating
drawings within a specific time limit. If you go over this time limit you are
burning up the profit margin, when we first are introduced to Revit we think to
ourselves "wow, this is going to save me a bunch of time", "I no
longer have to draw elevation, sections" etc... however my experience is
that we get seduced by Revit and we want to build a complete model down to the
nuts and bolts.
We need to model what is
appropriate to the project. If your doing a residential home do you really need
to model the gutters and drains? Do you need to model the gas meter on the side
of the house? For larger projects do you need to model the tactile strip at the
top of the stairs? Would detail lines in the view be sufficient. There is a
huge difference in resources between the two. Do you need to use the roof top
mechanical unit from the supplier that is detailed down to the nut and bolt?
Why not use a generic placeholder.
Try to use families that
are smaller in file size this will help your project file size to stay
manageable.
So try and stick to a LOD of 300 (Precise Geometry) instead of LOD
400 (Fabrication)......
