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Kurt Bieri


Currently ReluxKCalc can only be obtained as a pre-release on direct request! 02.05.2019

The Relux k-value calculator was developed for experts in the assessment of obstrusive light.

The program refers to the guidelines:

  • Hinweise zur Messung, Beurteilung und Minderung von Lichtimmissionen
    der Bund/Länder-Arbeitsgemeinschaft für Immissionsschutz (LAI) 2012
  • ÖNORM O 1052:2012 „Light pollution ― Measurement and evaluation“


  • CIE 150:2017 „Guide on the Limitation of the effects of obtrusive light from outdoor. (informativ)

Knowledge of these guidelines is a prerequisite for evaluating the calculation results and performing a practical glare assessment.

In order to use the k-value calculator, an appropriate license must be purchased. 

Detailed information can be found in our webshop Webshop.

How to install the license is described in the article "Paid licenses".

Using k-value calculator

After the license has been activated, you can create an outdoor scene in ReluxDesktop as usual. 

See further information in the Knowledge Database.

After you have entered the desired scene with the corresponding dimensions and luminaires, 

you can use the ribbon "Insert / Measurement object". 

A new luminous intensity measuring point can be selected and positioned at the desired position in the scene.

Hint: The size of the displayed light spot symbol in the ground plan can be set via Ground plan / Properties / Symbols.


Make sure that the option Glare rating ks is activated in the properties of the light intensity point.


The parameter:

L= luminace of the background/surroundings

k = proportionality factor


must be set according to the given specifications..

If a light intensity point with glare option enabled is included in the scene, 

an additional ribbon Glare rating obtrusive light  is available.

Glare rating

The glare evaluation of the scene can take place directly in the result window.

Important: For the evaluation, the correct or desired settings must be observed. See chapter "Settings".

If in the ribbon Glare rating  the option Determine dynamically  is activated, the results window will be updated each time the scene is adjusted.

For very complex scenes it may be necessary to switch off the dynamic mode and perform the calculation manually using the "Calculate" button.

In the list, the relevant values for each evaluation point in the scene and for each luminaire are displayed and highlighted in colour.

If a luminaire or a measuring point is selected in the list, the corresponding object in the scene is selected and adjustments can be made directly.

Please also note the display and filter functions in the Settings chapter.