What is the difference between COBie, IFC and BIM?

"The contractor shall provide BIM, IFC and COBie." A clause like that, with nothing to say what each is for, is a reliable way to buy duplicated effort and three inconsistent sets of information.

The three terms sit at different levels. BIM is a process: managing information about a built asset across its life cycle. IFC is an open data schema, published as ISO 16739-1, for exchanging that information between software applications. COBie is a defined exchange of the information needed to operate and maintain a facility's assets; NIBS, which maintains it, describes it as a non-graphic subset of a BIM model, defined as a model view definition (MVD) of IFC. All three can serve the same project, but they answer different questions and cannot stand in for one another.

The three side by side

One project, three jobs

On a typical project, BIM processes coordinate design and construction information; IFC is used to share models between disciplines and to hand over an open-format model; and COBie transfers the asset records the maintenance team will load into its system. The owner's requirements should state the purpose and the receiving system for each.

How they connect has practical consequences. Because COBie is defined as a view of IFC, COBie data can be generated from a well-structured model, and NIBS lists IFC alongside SpreadsheetML and JSON as approved COBie formats. That only works, though, if the model carries the identifiers, classifications and properties the COBie requirement needs. If it does not, the COBie file ends up assembled by hand from schedules, and falls steadily out of step with the model.

One pump, one identity

When the same pump appears in the model, the COBie file and the maintenance system, it must have one identity, with an agreed rule for which source wins when they disagree. The requirements should settle which deliverable is authoritative for each kind of information, whether geometry, asset identity or maintenance data; how identifiers are carried from one to another; and who resolves differences, and by when.

The receiving tools need testing as well. A product's claim to support IFC or COBie does not prove that every required field or relationship will transfer under the project's chosen versions and conventions.