[Radiance-general] gendaylit

[Ehsan Vazifeh]

Dear Jan and Greg,

Thank you all. using -O option solved the problem. I didn’t think about the spectrum other than visible. 

Cheers, Ehsan

On 30 Jul 2014, at 18:49, Jan Wienold <jan.wienold at epfl.ch> wrote:

> if you want to have solar raditaion output in W/m2, then you have to use the -O 1 option for gendaylit (see manpage).
> in your case, you get then 246 W/m2 calculated...
> 
> cheers,
> Jan 
> 
> Am 7/30/14, 6:36 PM, schrieb Ehsan M.Vazifeh:
>> Dear All,
>> 
>> I am using Perez sky model (gendaylit) in Radiance. When I calculate the horizontal irradiance and compare it with global irradiance sensor I get systematic error (rtrace gives around 70% lower values). I checked everything in between so far nothing was wrong in the code, Here is one sample:
>> 
>> gendaylit -ang 22.11 -64.30 -W 370.67 108.20 > genday_03_22_07_20.rad
>> 
>> then I add the sky description in the rad file:
>> 
>> skyfunc glow skyglow
>> 0
>> 0
>> 4 1 1 1 0
>> skyglow source sky
>> 0
>> 0
>> 4 0 0 1 180
>> 
>> void glow groundglow
>> 0
>> 0
>> 4 1 1 1 0
>> groundglow source ground
>> 0
>> 0
>> 4 0 0 -1 180
>> 
>> then I create an octree file:
>> 
>> oconv genday_03_22_07_20.rad > genday_03_22_07_20.oct
>> 
>> after that using rtrace I calculated the horizontal irradiance which is: 150.718 w/m^2
>> 
>> echo '0 0 0 0 0 1' | rtrace -w -ab 7 -ad 4096 -ar 512 -aa 0.1 -as 64 -I -h genday_03_22_07_20.oct | rcalc -e '$1=$1*0.265+$2*0.67+$3*0.065’
>> 
>> 150.718
>> 
>> but the measured global horizontal irradiance
>> (Pyranometer)
>> is 252.2 w/m^
>> 2 
>> 
>> I calculated this output for the whole year but still the Perez is significantly underestimating the horizontal irradiance. I should add that I used gensky to generate the same output and results showed gensky horizontal irradiance fit well with Pyranometer irradiance. Does anyone have any idea what is wrong here?
>> 
>> Thank you all, Ehsan
>> 
>> 
>> 
>> _______________________________________________
>> Radiance-general mailing list
>> Radiance-general at radiance-online.org
>> http://www.radiance-online.org/mailman/listinfo/radiance-general
> 
> _______________________________________________
> Radiance-general mailing list
> Radiance-general at radiance-online.org
> http://www.radiance-online.org/mailman/listinfo/radiance-general

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.radiance-online.org/pipermail/radiance-general/attachments/20140731/38d771ef/attachment-0001.html>