.IFC File Format

Introduction

IFC is the open standard for building information modelling (BIM), maintained by buildingSMART International and published as ISO 16739. Rather than lines and surfaces, an IFC model describes a building as objects: a site, a building, storeys, spaces, walls, slabs, doors, windows, pipes and ducts, each with its geometry, materials, properties and relationships.

Architects, engineers and contractors use IFC to exchange models between different BIM programs and to hand over a building’s data. The common versions are IFC2x3 and IFC4.

Structure

An .ifc file uses the same text encoding as STEP, ISO 10303-21. The header’s FILE_SCHEMA names the IFC version, and the DATA section lists numbered entities, each referring to others by number. Every building element has a globally unique id and an owner history, and objects are linked through relationship entities, such as the one that places elements in a storey.

ISO-10303-21;
HEADER;
FILE_SCHEMA(('IFC4'));
ENDSEC;
DATA;
#1=IFCPROJECT('2O2Fr$t4X7Zf8NOew3FLOH',$,'House',$,$,$,$,$,$);
#20=IFCBUILDINGSTOREY('0eBbL5mQf0vBhWl2VZbVDn',$,'Ground floor',$,$,$,$,$,.ELEMENT.,0.);
#30=IFCWALL('1kTvXnbbzCWw8lcMd1dR4o',$,'Wall 1',$,$,$,$,$,$);
ENDSEC;
END-ISO-10303-21;

The same model can also be written as XML (.ifcxml), or zipped (.ifczip).

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