This year I attended the bSI’s Summit in Paris and had the opportunity to learn and network among the industry’s top critical thinkers for interoperability. The theme I took away from the summit was that the IFC framework is expanding its capabilities to consider geographic information systems (GIS). Incorporating the GIS perspective will fundamentally challenge the rules we’ve laid out for building information modeling (BIM).
One topic that was under fire in the building room was the level of development (LOD) classification system. The debate was about the levels 100 to 500 and why can’t they be called levels 1 to 5, or A to E? There was no consensus at the end of the debate as to which approach we should use or how we should unify the different perspectives. Fortunately, the technical sessions helped me understand the building blocks of an information classification system.
Level of development has been the primary term for defining modeled elements but in the past few years new terms have emerged such as level of information (LOI) and level of geometry (LOG). These terms can be collectively referred by the generic term of Level of X (LOX). You can use LOX to define your scope of work and form an agreement to deliver certain model uses.
There are many types of model uses but the ones I typically encounter are for construction documentation and clash detection. The LOD between these two uses would vary from 300 to 400 but if we included the LOI and LOG then we could add new layers of granularity to this equation. This allows us to break down the LOX and configure a set of parameters for each information level or phase.
Most coordinated drawing sets must comply with local energy regulations but rarely is the energy analysis included as a model use (large/complex models are rebuilt using BEM tool). The reason for this is because the analysis phase requires a lower LOG to facilitate an effective data transfer using file formats (IFC/gbXML). This ensures the space boundary conditions are met which allows for the transfer of information such as energy settings and thermal properties. Each analysis type (energy, daylight, comfort, etc.) can define its own set of LOI in the exchange requirements (ER). It’s much easier to increase the LOG than to lower it.
I came to the summit to share my experience with integrating BIM with energy modeling. Together with the technical group we’re exploring a model view definition (MVD) for energy analysis which aims to capture the necessary information to run a simulation. This feature is still under development, but in the meantime, we can keep refining our information classification system to accommodate discipline-specific model uses.
||2. Analysis||3. Coordination|
|Level of Development||50||50||300|
|Level of Information||50||200||300|
|Level of Geometry||0||75||300|