A sufficient supply of daylight and an adequate line of sight to the outside are essential requirements for both the well-being and the motivation of people who spend time in buildings. The required illuminance levels can be met by artificial light, daylight or a combination of both.

Daylight is calculated in DIALux evo using three different sky models described in CIE 110-1994: 

  •  overcast sky 
  •  average sky 
  •  clear sky 

The daylight quotient required in some standards can only be calculated when the sky is overcast. DIALux evo automatically creates a corresponding light scene when a daylight calculation is performed. Direct sunlight can only be calculated when the sky is clear or average.

The illuminance calculation is only carried out in the interior and only through daylight-relevant windows that direct daylight into the interior of the building. Other building openings are not taken into account in the daylight calculation. Windows that are located inside the building are not daylight-relevant. In most cases, DIALux recognises this automatically. If necessary, this setting can be changed at the window in the apertures tool.

Outside buildings, the scene is only visually brightened for visualisation. No illuminance levels are calculated. 

Location and site alignment

You define the location together with your building in the site tool in construction mode.

You can either select a location directly from the list or enter latitude and longitude yourself. You can change the orientation of your building using the "Draw north arrow" action. Simply draw with the arrow in the 2D floor plan of your scenes.


The "Draw north arrow" function only works in the floor plan. Alternatively, you can enter the north orientation directly as a number of degrees.

Calculating with daylight - Creating a daylight scene

To calculate daylight with DIALux evo, create a light scene. You will find the corresponding tool in the Light mode.

You create a daylight scene by selecting a sky model other than "No daylight" in the light scene tool.

In connection with a window in your project, DIALux evo recognises a daylight scene, which you can also see by the fact that the "Start calculation" icon is switched to active.

In each light scene, you will find an area for daylight next to the luminaire groups. Here you select the desired CIE sky model, select date and time and activate the option "Direct sunlight" if required.  


The direct sunlight option is only available if you have not selected overcast sky as the sky.

It is up to you whether you also want to take artificial light into account when calculating the daylight. For a pure daylight scene, you must remove all luminaire groups from the light scene or dim all luminaires down to 0%. You can create as many light scenes as you like with and without artificial light, each with a different date, time and sky model.


As soon as you create a light scene with daylight quotient, another light scene "Light scene for daylight factor" is automatically created. With this automatically created light scene, the sky model "overcast sky" is always selected. With this light scene, a daylight quotient can always be displayed in the documentation.


The documentation for daylight scenes does not require any special settings. In addition to the photometric results, it only contains information on location, date, time, sky model and zenith luminance. A daylight quotient is always given in the summary.