How IFC describes a luminaire
IFC (Industry Foundation Classes, ISO 16739) is the open exchange format for BIM. A luminaire is an occurrence placed in the building, usually linked to a type that holds its shared properties.
| What | IFC4 | IFC2x3 |
|---|---|---|
| Luminaire occurrence | IfcLightFixture (or IfcLamp) | IfcFlowTerminal |
| Luminaire type | IfcLightFixtureType | IfcLightFixtureType |
| Link from occurrence to type | IfcRelDefinesByType | IfcRelDefinesByType |
| Position | IfcLocalPlacement chain | IfcLocalPlacement chain |
| Storey | IfcRelContainedInSpatialStructure | IfcRelContainedInSpatialStructure |
Product identity lives in property sets. Pset_ManufacturerTypeInformation carries Manufacturer, ModelLabel and ArticleNumber; the light fixture and lamp property sets can carry colour temperature, luminous flux and wattage. Many authoring tools also write their own property sets with similar names.
Exporting it well
- Export IFC4 (Reference View) where your tool supports it; IFC2x3 Coordination View also works.
- Include the lighting fixtures category and type properties in the export, not only the building fabric.
- Fill in manufacturer, model and article number on the luminaire type. The article number is what makes an exact product match possible.
- Keep the model's length unit declared (millimetres or metres). An importer should read it from the file, not guess it.
- If the tool can only export meshes, name the luminaire objects clearly in an OBJ export (for example Downlight_01 or a Lighting Fixtures group).
Positions are design intent
A BIM model says where a luminaire was designed to go. It is not a survey of where it was installed, and it does not know DMX addresses, controller ports or wiring. Treat imported positions as a strong starting point and confirm them on site before the installation is commissioned.
How Lightshaped imports it
- Reads IFC2x3 and IFC4, resolving units, placement chains, storeys and property sets, and tessellates the building as non-emitting reference geometry.
- Finds luminaires by IFC class, by luminaire type, or by name for proxies, and skips things that only sound like lights, such as light switches and skylights.
- Groups them by type so you review a handful of types instead of hundreds of instances.
- Maps a type to a OneEightyOne product only on an exact published article number or model name. Other brands stay labelled as the project's own luminaires.
- Keeps the result in simulation until commissioning evidence exists; physical output stays locked.
Questions people ask
- Which IFC entity is a light fixture?
- In IFC4 it is IfcLightFixture (or IfcLamp for a lamp). In IFC2x3 luminaires are usually IfcFlowTerminal elements typed by an IfcLightFixtureType.
- Can I import luminaires from a Revit model?
- Yes, through an IFC export that includes the lighting fixtures category and their type properties. Revit's IFC exporter can map manufacturer and model into Pset_ManufacturerTypeInformation.
- What if my model has no lighting yet?
- The building still imports as a 3D reference. You can then place products by hand or ask Lightshaped's AI to propose a design against the real geometry.