What is BIM?

BIM is is short for “Building Information Modeling”.  The entire project is a database.  Every wall has volume and layers of construction material.  Every roof has a defined slope, area and material;  Every window has surface area of glazing that can be used in a heat loss calculation.  You can literally calculate the number of roof tiles in your project.  If you have need for that information, it’s readily available. 

In a more practical sense, BIM is coordination.  It’s less expensive to make a change early in the design phase than it is to make a change during construction.  Finding conflicts early leads to a more pure design, lower cost of construction and fewer delays.

Single Data Entry

When entering a piece of data, like a sheet name and number, you should only have to enter it once.

Single Element Entry

In the same way data should be entered only once, building elements should only be entered once.  Take a column, for example.  The shaft of the column should show on all plans as well as the Reflected Ceiling Plan.  The base of the column should show in the plans, but not in the Reflected Ceiling Plan.  The capital of the column should show on the Reflected Ceiling plan, but not on other plans.  Placing the column in 3 pieces on appropriate layers satisfies Single Element Entry.

Then add some “craft”

Adding detail to a building element adds character.  But, it should be added in such a way that it looks correct in multiple rendering styles as well as in elevation and section.

Then, that one piece of data will show wherever it is needed.  If the sheet name or number ever changes, you need to update the info in only one place, then all references have been corrected.

GDL - the BIM “App” language

For more complex modeling and coordination, the GDL programming language can be used to create Parametric GDL Objects (or BIM apps, if you will).  One simple example is a door, which should be open in plan, but closed in 3D.  GDL objects can be as simple as a custom door panel or as complex as an entire pre-manufactured building complete with components tallied and staged to the side.  Or, this partial Icosahedron:

BIM changes the work flow

By coordinating the project better during the design process, the project man-hour distribution is shifted to the beginning of the project.  The earlier a change is made, the less expensive the change is in time and money.  This is a more efficient model.