Dear John,
to my knowledge, the Perez model only works in a limited range for the sky
clearness and brightness; at least gendaylit does. In the new version of
gendaylit that has been announced yesterday, the sky clearness and
brightness values are set to the border values in your case, and the
output is still calculated. Therefore, the octree can still be created and
used for this time step, without the bash script being aborted ("bad sky
description"). The warning messages are still directed to stdout as long
as the -w option is not set.
My guess is a wrong combination of high direct-normal irradiance values
and the defined point of time. Do you apply hourly irradiance values? Does
the problem still exist if you change the calculation to 10-minute values?
Maybe you can recalculate your weather files with the Skartveit-Olseth
method (Meteonorm, for example, provides this option.)
Cheers,
Wendelin
Wendelin,
Thanks for your response. I've tried the new gendaylit and am getting the same results, below.
$ gendaylit 2 1 8.5 -a -20.27 -o -148.73 -m -150 -W 1031 44
# gendaylit 2 1 8.5 -a -20.27 -o -148.73 -m -150 -W 1031 44
sky clearness or sky brightness out of range 13.563423 0.052832
[email protected]
0411 519 738
Relume Consulting
···
On 02/02/2013, at 2:03 AM, [email protected] wrote:
Dear John,
to my knowledge, the Perez model only works in a limited range for the sky clearness and brightness; at least gendaylit does. In the new version of gendaylit that has been announced yesterday, the sky clearness and brightness values are set to the border values in your case, and the output is still calculated. Therefore, the octree can still be created and used for this time step, without the bash script being aborted ("bad sky description"). The warning messages are still directed to stdout as long as the -w option is not set.
My guess is a wrong combination of high direct-normal irradiance values and the defined point of time. Do you apply hourly irradiance values? Does the problem still exist if you change the calculation to 10-minute values? Maybe you can recalculate your weather files with the Skartveit-Olseth method (Meteonorm, for example, provides this option.)
Cheers,
Wendelin
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Hi John,
are you sure you are using the updated version (2.0)? I've just tried it and it gives the result below, which is different from yours. Of course it is still beyond the Perez parameters, but it delivers a result.
Maybe you still have an old version in your PATH.
You can find out the version number by just typing gendaylit, then you should get following output - in the last line it gives you the version number:
gendaylit
Usage: gendaylit month day hour [-P|-W|-L|-G] direct_value diffuse_value [options]
or: gendaylit -ang altitude azimuth [-P|-W|-L|-G] direct_value diffuse_value [options]
-P epsilon delta (these are the Perez parameters)
-W direct-normal-irradiance diffuse-horizontal-irradiance (W/m^2)
-L direct-normal-illuminance diffuse-horizontal-illuminance (lux)
-G direct-horizontal-irradiance diffuse-horizontal-irradiance (W/m^2)
-O [0|1|2] (0=output in W/m^2/sr visible, 1=output in W/m^2/sr solar, 2=output in candela/m^2), default is 0
gendaylit version 2.00 (2013/01/28)
Cheers,
Jan
here is the output of gendaylit 2.0 using your input data:
gendaylit 2 1 8.5 -a -20.27 -o -148.73 -m -150 -W 1031 44
# gendaylit 2 1 8.5 -a -20.27 -o -148.73 -m -150 -W 1031 44
Range warning: sky clearness too high (12.000000)
void light solar
0
3 8.668e+06 8.668e+06 8.668e+06
solar source sun
0
4 0.801290 -0.101186 0.589658 0.533000
void brightfunc skyfunc
2 skybright perezlum.cal
0
10 2.241e+01 2.418e+01 -0.982491 -0.175085 17.744335 -6.114169 1.021923 0.801290 -0.101186 0.589658
gendaylit 2 1 8.5 -a -20.27 -o -148.73 -m -150 -W 1031 44
···
On 02/03/2013 11:12 AM, John Ford wrote:
Wendelin,
Thanks for your response. I've tried the new gendaylit and am getting the same results, below.
$ gendaylit 2 1 8.5 -a -20.27 -o -148.73 -m -150 -W 1031 44
# gendaylit 2 1 8.5 -a -20.27 -o -148.73 -m -150 -W 1031 44
sky clearness or sky brightness out of range 13.5634230.052832
[email protected] <mailto:[email protected]>
0411 519 738
Relume Consulting
On 02/02/2013, at 2:03 AM, [email protected] > <mailto:[email protected]> wrote:
Dear John,
to my knowledge, the Perez model only works in a limited range for the sky clearness and brightness; at least gendaylit does. In the new version of gendaylit that has been announced yesterday, the sky clearness and brightness values are set to the border values in your case, and the output is still calculated. Therefore, the octree can still be created and used for this time step, without the bash script being aborted ("bad sky description"). The warning messages are still directed to stdout as long as the -w option is not set.
My guess is a wrong combination of high direct-normal irradiance values and the defined point of time. Do you apply hourly irradiance values? Does the problem still exist if you change the calculation to 10-minute values? Maybe you can recalculate your weather files with the Skartveit-Olseth method (Meteonorm, for example, provides this option.)
Cheers,
Wendelin
_______________________________________________
Radiance-general mailing list
[email protected] <mailto:[email protected]>
http://www.radiance-online.org/mailman/listinfo/radiance-general
_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general
--
Dr.-Ing. Jan Wienold
Head of Team Passive Systems and Daylighting
Fraunhofer-Institut für Solare Energiesysteme
Thermal Systems and Buildings
Heidenhofstr. 2, 79110 Freiburg, Germany
Phone: +49(0)761 4588 5133 Fax:+49(0)761 4588 9133
[email protected]
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