IFC: the vendor-neutral model format (ISO 16739)

How IFC differs from a drawing file

In a DWG file, a wall is a pair of lines on a layer. In an IFC file, the same wall is an object of the class “wall” with height, thickness, material and assignment to a storey. That is why IFC allows you to derive something that cannot be derived from a drawing: quantities, areas, assignments, checking rules.

For building operation, this is the decisive point. A CAFM system does not import lines but rooms and equipment with their properties.

The exchange involves losses

IFC is an exchange format, not a working format. On export, whatever the target format does not know is left behind: vendor-specific parameters, families and types, display rules, annotation logic. An IFC model carries the geometry and the agreed properties, not the editability of the source model.

This leads to the rule by which we deliver: wherever possible, we model natively in the client’s CAD system, and IFC is supplied in addition as a neutral exchange and archive format. If you order only IFC, you get a model that anyone can open and nobody can continue to edit.

What is agreed before the order

• The IFC version. IFC4 and the older IFC2x3 are not identical. Which one is read is decided by the target system.
• The scope of properties. Which attributes should be attached to which component follows from the purpose, not from the maximum. The term for this is the level of information need.
• The test import. An IFC file that nobody has opened in the target system is an assumption. For portfolios, the test import is run on a pilot property before the series begins.