[Radiance-general] Gendaylit Visible radiation

[Julien Boutillier]

Hi Jan, 

Thanks for the explanation.

I'll test this gendaylit update. 

Cheers, 

Julien
Le 31 janv. 2013 à 15:01, Jan Wienold a écrit :

> Hi Julien,
> 
> Using  the default option (-O 0 ) gendaylit "transfers" the solar radiation into visible radiation, using a luminance efficacy model.
> Therefore the "sky irradiation" (=equals visible irradiation) differs also from situation to situation. The luminance efficacy of the sun is much lower than for the sky and this is taken into account by the model.
> 
> So for your case
> 
> gendaylit 6 21 12:00GMT -a 46.51 -o -6.56 -m -15 -G 500 200
> 
> you get
> 425 W/m² visible radiation
> 
> if you use
> 
> gendaylit 6 21 12:00GMT -a 46.51 -o -6.56 -m -15 -O 1 -G 500 200
> you get
> 695 W/m² solar radiation  which is +- the input radiation of 500+200=700W/m²
> 
> So the results are as expected.
> 
> The included luiminance efficacy model works properly within gendaylit - at least a recently internal performed validation study on measured data showed this.
> 
> By the way, my colleague will announce later today a major update of gendaylit, which have some significant improvements included.
> 
> Cheers,
> 
> Jan
> 
> 
> 
> On 01/31/2013 11:56 AM, Julien Boutillier wrote:
>> Hi everyone,
>> 
>> I 'm using gendaylit function to generate sky with visible spectrum only. I introduce horizontal direct irradiance and horizontal diffuse irradiance (-G parameter) which are computed from horizontal global irradiance (meteo data : full spectrum).
>> 
>> I don't understand why sky irrandiance in Radiance is approximatively 60% of horizontal global irradiance. In my mind, the visible spectrum is approximatively 40-45% of full spectrum, is it wrong?
>> 
>> Example gendaylit command :
>> 	
>> 	gendaylit 6 21 12:00GMT -a 46.51 -o -6.56 -m -15 -G 500 200
>> 
>> Thanks for your answer.
>> 
>> Cheers
>> Julien
>> 
>> 
>> 
>> _______________________________________________
>> Radiance-general mailing list
>> Radiance-general at radiance-online.org
>> 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
> 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
> 
> 
> _______________________________________________
> Radiance-general mailing list
> Radiance-general at radiance-online.org
> http://www.radiance-online.org/mailman/listinfo/radiance-general