IFC gives its users many free spaces and interpretive spaces. In doing so, mistakes/misinterpretations/inaccuracies/imperfections are sneaking in, which pose problems for the planner to import IFC files into DIALux evo. This page helps the user with the design, in order to create good conditions for processing with DIALux evo when exporting and importing.


  • Logical structures
    • DIALux evo 7 requires at least one building with a storey and walls. Without (logical) building the import is canceled.
    • IFC offers topological information and DIALux evo relies for its navigation. Of course you CAN put different modules in different storeys, in order to show and hide them via the storey switch. However, this is not very useful for the navigation and output of evo.


These points refer less to DIALux than to those CAD programs in which the user constructs IFC files. Many of these programs definitely avoid some of the errors listed here, but unfortunately not all of them. 

The planner should pay attention to this:

  • Clean construction
    • BIM means (also) virtual constructing and requires the same degree of precision as it is later in the real construction of the case.That means:
      • If there is a gap between two walls, there is a gap.
      • If a component is placed in a wall, it is placed in the wall.
      • If a window intrudes 3 mm into a second wall, it intrudes 3 mm into the second wall.

With "it is clear what I mean" the fewest CAD programs can handle something.

Errors in accuracy cause:

  • Performance problems
  • Problems in room detection
  • Problems with calculation accuracy
  • Improper visualization
  • Display problems

  • Completely construction

          Paper/DWG is patient, BIM less. If a floor is not explicitly present as an object, then it is missing in terms of statics, quantity of material, isolation and stability of the residents.

  • Windows with cut-outs

DIALux automatically places an appropriate cut-out for each window. Other CAD programs don’t do this, but this is not necessarily wrong. When for example a concrete shell wall is constructed, this wall has an opening, but not a suitable building opening, at the intended location. On the other hand a window manufacturer provides a window, but without a suitable building opening! The IFC ideally supplies cut-outs and windows with respect to each other so that the cut-out is also adapted when the window is being adjusted. If the opening and thewindow are not related to each other, the window is moved in evo without the shell opening being adapted.

  • Use correct object types

IFC allows objects to be used without the correct type description and only with their geometry, e.g. toilets, elevators etc. These objects, however, do not have any function recognizable for the software and are not correctly considered for connections and power calculation. For DIALux evo it is for example important that windows are also defined as windows (and not as walls or furniture), otherwise daylight can’t be calculated.

Supported objects

The user can’t fully understand the supported and not-supported objects. If you want to have a look at the complete IFC documentation and download it, please open the homepage: http://www.buildingsmart.de/ page.

The following IFC objects are taken into account during import and were converted to DIALux objects:

  • IfcWall
  • IfcStandardWallCase
  • IfcCurtainWall
  • IfcSlab
  • IfcRoof
  • IfcCovering
  • IfcWindow
  • IfcDoor
  • IfcColumn
  • IfcBeam
  • IfcStair
  • IfcStairFlight
  • IfcRailing
  • IfcFooting
  • IfcPlate
  • IfcMember
  • IfcElementAssembly
  • IfcDiscreteAccessory
  • IfcFurnishingElement
  • IfcBuildingElementProxy
  • IfcProject
  • IfcSite
  • IfcBuilding
  • IfcSurfaceStyleRendering
  • IfcSurfaceStyleShading
  • IfcSurfaceStyleLighting
  • IfcSurfaceStyleRefraction

Not supported objects

The following IFC objects are not imported. They do not appear after importing into DIALux evo. We have not yet implemented these objects because of time reasons or that they are not relevant for the lighting planning in our eyes. The list is not complete and will be supplemented over time:

  • IFCFlowTerminal
  • IFCMaterial
  • IfcSurfaceStyleWithTextures
  • IfcExternallyDefinedSurfaceStyle
  • IfcDistributionElement
  • fcVirtualElement


Here you can find technical export settings that allow some CAD programs.

We recommend these export settings for DIALux:

  • Version IFC 2x3 - DIALux is currently being imported only IFC files in this format.
  • Geometry BREP - DIALux prefers geometries as BREP (Boundary Representation - boundary surface model, description of objects by their limiting surfaces). Evo comes along better with non-triangulated surfaces. The surfaces should be oriented correctly and form a closed volume, which unfortunately is not self-evident in many CAD programs.
  • Multilayer components: These components should not be separated into individual objects.
  • Elements in Solid Element operations: Yes, as BREP
  • Elements with connections: Yes, as BREP
  • Ceilings with inclined side surfaces: Yes, as BREP
  • IFC terrain information: Yes, as BREP
  • IFC plot of land: on project origin                                                                                                                                         

These settings are possible, but may cause performance or cutting problems:

  • BREP with triangulated surfaces (slower than non-triangulated BREPS)
  • linearly extruded geometry (risk of cutting problems)
  • Multi-layered elements, separated into individual objects (slower, later processing of the individual elements not possible)

These settings are not supported by DIALux:

  • Version IFC 4 is currently not supported
  • Rotated extruded geometry


With the IFC import, we will deal with much larger projects in the future. "Larger" in terms of file size, amount of surfaces and constructed square meters. Large does not necessarily mean slow, but it can.

Here are a few optimizations, which the user himself has in his hand:

  • Furniture

While the real building consists only of 12 to several hundred surfaces, a single piece of furniture or decoration can quickly consist of several tens thousands of surfaces. The user should consider whether these objects are relevant for their light calculation and whether they must export them at all. Possibly. He can also deselect furniture during the import. Alternatively, only the bounding box can be exported. DIALux evo uses the bounding box (if present) as a fallback if the actual geometry is defective.

  • Whole buildings

The entire building is not always necessary for the exemplary lighting planning. Sometimes it is enough to import the affected storey.