UDI results

Hi all

I got the results of daylight simulation in the room in lux. the results(in 3 different times of the year) are between 100-3000 lux, with some parts near window, approximately in range of 20000-40000 lux but know I have problem in analysing the annual results. I checked it in lux and DF, but the UDI results seemed different.

In the range between 500-2500 lux, the UDI is 0.0 for each point in the room. and 98% is more than range(more than 30000). but its not normal.

could someone help me?

thank you in advance.

001.gh (889 KB)
IRN_Shiraz.408480_ITMY.epw (1.62 MB)

Hi Masoumeh,

Are you changing the north direction for annual analysis? There was a bug that the results would be only for the first time which is fixed now. Have you updated your component?


Hi mostafa,

I changed the direction by rotating in rhino modelling at first.

I’m working with HB 0.0.60 now. I will check the new version. I’ll tell you about it.

thank you.


Dear mostafa,

I updated HB today, only “generate test points component” in my file is updated to 01-DEC, and others are still for 07-NOV. but the UDI result is the same as before.

thank you


Hello all again,

is there anyway that I can solve this problem with UDI?



Your errors were due mostly to your materials, which had properties like 0.01 reflectance. Properties like this do not occur in nature unless we are talking about a black hole or something that theoretically approaches a black body. Once you boost up this reflectance to reasonable values (like 0.25) or take default materials, you start getting simulations that make sense (see attached file).

Mostapha, should we put in a warning if a user inputs a reflectance below 0.1? It seems to not only be incorrect from a physical properties standpoint but it also seems to make DAYSIM go crazy and completely discount the dark surface from the simulation (causing some big disagreements between illuminance studies from Radiance and an annual simulation with DAYSIM with the same HBObjects).


001_CWM.gh (865 KB)

Hi Chris,

thank you very much for this hint. got it.