[Radiance-general] DAYSIM vs. Radiance illuminance values

[Nicolas Roy]

Hi,

I'm making a short comparison between illuminance values obtained in 
DAYSIM and Radiance for a specific day/time, and the results I obtain show 
a  ratherbig difference with Radiance having values twice as high.

I compare the values in the annual illuminance profil (.ill) generated by 
DAYSIM, with values I obtained in Radiance for the same day/time. I 
defined the Radiance sky description using the "direct normal irradiance" 
and the "diffuse horizontal irradiance" values from the climate data used 
in DAYSIM. 

What can be the source of such large differences?


I use the following in Radiance:

##sky

gensky 6 21 12.5 -a 52.47 -o -15.4 -m -15 -r 35 -B 363 > sky001.rad


##out.rad

skyfunc glow sky_glow
0
0
4                0.9                0.9               1.15  0

sky_glow source sky
0
0
4                  0                  0                  1 180

#a green ground
skyfunc glow ground_glow
0
0
4                0.2                    0.2               0.2     0

ground_glow source ground
0
0
4                  0                  0                 -1 180

##rtrace rcalc run

oconv sky001.rad out.rad material.rad geometry.rad > 001.oct
rtrace -w -h -I+ @options.opt 001.oct < sensors.inp | rcalc -e 
'$1=($1*0.265+$2*0.670+$3*0.065)*179' > 001.ill



-Nicolas

nicolas.roy at velux.com





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