LoD: “Detail” or “Development” for Integrated Models?

A great visual description of LoD provided by Lanmar Services.
A great visual description of LoD provided by Lanmar Services.

I try hard to mark how collaborators describe LoD in casual language during my introductory meetings as a BIM Consultant. Architects’ understanding of the acronym tends to be an accurate predictor of how they view the role of their building information model, and thus the fate of their integration meetings.

LoD has changed from “Level of Detail” to “Level of Development” over the last decade. This may seem minor, but it signals a significant change for the utility of BIM.

Jim Bedrick of AECbytes reports that Graphisoft first coined LoD as “Level of Detail” in the early 2000s. This is a reasonable step for a BIM software firm concerned with the amount of detail — and thus memory — the software would handle with system resources. The more detailed a model, the slower it would respond on computers.

The problem is that not all building detail is helpful to designers during project delivery. Modeling baseboards did not contribute to any coordination meeting I have attended. Modeling door hardware only burdens collaborating engineers as they work in linked models. Focusing on quantity of model input didn’t correlate with the model’s usefulness.

Quality of model information is less important than quality of model input.

I have watched the definition of LoD shift with the spread of this realization. Teams growing used to integrated delivery workflows are focused instead on what design decisions can be “locked down” at various stages of model development. They guard against interns modeling in superfluous elements merely to create detailed interior elevations. Instead, they ask collaborating engineers to model needed machine room spaces as early as possible so the decisions about enclosure, structure, and circulation can proceed rapidly.

My expertise as a BIM Consultant isn’t needed long on teams that use the term, “Level of Development.” Those architects are making decisions from model feedback. They don’t bother with superfluous details in their drawings, such as custom section cut heads; they’re too busy developing the forest to detail the trees’ bark.