Detailed UGR calculation issue

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Joined: Thu Jul 19, 2018 4:23 pm

Detailed UGR calculation issue

Post by isidoros » Mon Jul 23, 2018 8:08 am

Dear members,
I am quite satisfied with the capabilities and enhancements that are provided with the latest version of Dialux evo. Although, I face a problem in the calculation of UGR in an internal space. The dimensions of the room are 8m x 8m x 2.8m and inside it are placed 9 luminaire PHILIPS CR434B W60L60 1xLED48_830 AC-MLO.

Trying to estimate the UGR in this room manually according CIE 1995 and the basic UGR formula, the results differ from Dialux calculation. In fact, all the parameters are calculated in detail in excel below, but unfortunately the result is not the same. Struggling to find the solution and after a lot of iterations on calculation, I strongly believe that the difference on the result are caused from the Indirect illuminance calculation “Lb”. Just in case that one will change the value of Indirect illuminance in my .xlsm archieve can generate a valid value like Dialux application.

UGR = 8*log(0.25 Σ (Li^2*Ω)/(Lb *p^2)

Could you provide me guidance or technical documentation with the functions which are used to calculate the indirect illuminance on Dialux?
In fact, I realized that the calculation of indirect illuminance is a controversial issue, which is not so clear taking into account the following technical documentation links and the standards. (related links according previous discussions on forum)

Below, one can find the project on Dialux, the Excel calculation file and a simple schematic diagram of my test case project in a dwg drawing ... 7YD9a?dl=0

related links according previous discussions on forum ... gr-method/

Thank you in advance,
Best regards
Isidoros Siderakis

Posts: 1322
Joined: Thu Jul 26, 2012 10:16 am

Re: Detailed UGR calculation issue

Post by T.Magenheimer » Tue Aug 07, 2018 8:43 am

Dear isidoros,

We use a complex mathematical procedure to calculate the indirect light component, which we do not disclose.

Please read the following articles about the UGR calculation in our DIALux evo knowledge base: ... are-rating ... 116115-ugr

Best reagrds,
Your DIAL Support Team


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