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New calculation parameters for light immission and obtrusive light with DIALux evo 13

DIALux

With the DIALux evo 13 version, we support you in the evaluation of obtrusive light sources, light immission and glare. Without much effort, you can calculate the variables

  • Luminous intensity I[cd]
  • Illuminance E [lx]
  • Glare rate RG
  • luminous flux ratios Ruf, Rul, Rulo, Rdlo
  • and the proportionality factor Ks

for incident light scenes as a new value, i.e. with a maintenance factor of 1.

Most of these values have long been part of everyday tools and are basic lighting parameters. The glare value Rg has been updated so that you can define the area for determining the veiling luminance more precisely. However, the glare value ks is new for many designers. In DIALux evo 13, you can calculate the ks value free of charge.

We explain exactly how the ks value is determined and how to work with it.


What is ks?


In some standards, such as CIE 150_2017, the value has existed indirectly for some time. It serves as a proportionality factor for determining the maximum tolerable luminance.

The ks value helps you to evaluate the glare effect of a light source by determining how much brighter the light source may be in relation to its surroundings. The distance to the illuminated surface is also taken into account via the solid angle.

The glare rate ks is defined as follows:

  • LS: Luminance of the light source (in candela per square meter, cd/m²).
  • ΩS: Solid angle of the light source (in steradian, sr), i.e. how large the light source appears from the viewer's perspective.
  • LU: Luminance of the surroundings (also in candela per square meter).

The glare value shows how bright the light source appears in comparison to its surroundings. The higher the value, the more disturbing the light source is perceived.

In certain scenarios, the value of ks can be very high. There are limit values for kSin various areas, e.g. residential areas or commercial areas. They range between 32 and 160, depending on the time of use. If these limit values are exceeded, measures such as shielding or rearranging the light source can help to reduce the glare.

To make things easier for you, we are working on the upcoming DIALux versions to compare the values determined with the specifications from the standards and to identify the sources of obtrusive light.

Now it's your turn: Do you use the ks value, how do you work with it, what are your experiences?