[Radiance-general] Gendaylit- bad sky description (John Ford)

[Jan Wienold]

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
0
3 8.668e+06 8.668e+06 8.668e+06

solar source sun
0
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
>
>
> john at relume.com.au <mailto:john at relume.com.au>
> 0411 519 738
> Relume Consulting
>
>
>
> On 02/02/2013, at 2:03 AM, Wendelin.Sprenger at ise.fraunhofer.de 
> <mailto:Wendelin.Sprenger at ise.fraunhofer.de> 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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>
>
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-- 
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
jan.wienold at ise.fraunhofer.de
http://www.ise.fraunhofer.de

In office:
Mo,Tue: 8:30-18:00
We,Thu: 8:30-16:00
Fr:  8:30-15:30

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