BIM Properties
One of the key ideas about Building Information Models (BIM) is that a BIM should contain not only the geometry of the building, but also "information" about the building. An important part of this information is the set attributes describing the objects in a BIM.
There are many ways to think about the information that has to be captured during design and then maintained during building operations, maintenance, and renovation. Consider the list of properties that you might assign to the pump shown in the image below.
Hallberg, Ingvar. "Pump." Google Sketchup 3D Warehouse, 2006.
The designer may think about a pump from the point of view of the capacity of the combined pump and impeller. The designer may also indicate the type of power that needed by the motor.
The specification writer may also consider the quality of the equipment and indicate the required efficiency rating of the unit.
Both the designer's and specifier's properties are required to correctly size and purchase equipment needed for the overall mechanical system to provide the necessary services. There are, however, other properties that still must be considered once the pump and impeller begin operation.
An operator may, however, be more concerned with the specific design of the bolt holes in the pump base plate and the exact specification of impeller inlet and outlet piping. Without specification of such equipment the concrete pump pad and or piping systems may require modification.
Of course, different types of products, materials, assemblies, and systems within the building should have different properties in the BIM. For example, it may not be meaningful for the color of the pump to be specified, however, for an assembly such as a kitchen wall the color of the wall may be its most important characteristic. Other properties pertain to both products and assemblies. For example a fire rated wall will itself be composed of products such as drywall and doors that have their own fire rating as well.
Key stakeholder in the decision of who decide what information is required and when it should be provided are the product manufacturers and replacement parts suppliers. Equipment manufacturer trade associations are the critical link to provide information. Associations can assist in the standardization of the information provided during the project life-cycle. Moreover, as standards emerge the nature of the information can begin to be transformed from images of exploded parts diagrams to spreadsheets containing the specific ordering information for individual parts and related suppliers.
The Specifications Consultants in Independent Practice (SCIP) thru the buildingSMART alliance and with the help of the Construction Specifications Institute (CSI) , software companies, and public and private sector representatives have been working to create property set templates that may form the basis for the start of a nation-wide dialog about the properties that should be considered the minimum standard set of information to be included in a BIM. This effort is organized around the buildingSMART alliance's Specifier's Properties Information Exchange project.