Illuminance data from different daylight sources

Dear,

I am a student at the KULeuven and currently working on a master thesis about estimating the health effects of daylight in a room. So far, I've been using the program DIVA for Grasshopper (McNeel), which counts on Radiance for light calculations. However, I am unable to retrieve the data from it that need. I am therefore considering to dig a little deeper into the underlying commands, and start working in Radiance instead.

The main idea for the calculation is to weigh the values of the intensity measured inside to the spectral distribution of the light source (outside). I would like to approach this problem using the CIE illuminants for direct sunlight, cloudy sky and clear blue sky (as suggested by Mardaljevic et al., 2013). As an output of Radiance, I thus expect:
- illuminance values inside, resulting from direct sunlight only
- illuminance values inside, resulting from cloudy sky only
- illuminance values inside, resulting from clear blue sky only
- or, a way to retrieve the contribution of clouded/clear sky to the light coming from the sky dome, using a sky cover coefficient

Before I start my adventure in Radiance, I would like to know:
- is it possible to retrieve this kind of data from Radiance?
- how would you suggest doing this?

Thanks in advance,
Kind regards,

Andrea Laenens

Bonjour,

Je suis actuellement en vacances. Je serai de retour le 7 août 2017.

En cas d'urgence, vous pouvez toujours appeler le numéro général d'Estia : +41 (0) 21/510.59.59 ou envoyer un mail à l'adresse [email protected].

Pour toutes questions relatives à DIAL+, merci d'utiliser l'adresse mail [email protected].

Cordialement

Julien Boutillier
Estia SA

Hi Andrea,

If I understood your question correctly, I would say it is definitely
possible to get all that data from a Radiance Model and, after
understanding how the command line and Radiance programs work, should not
really be that hard.

The programs GENSKY allows you define CIE clear and overcast skies, and
even control the color of the sky and ignore the sun. You can always delete
the sky as well, and use a black (i.e. 0% reflection) model for calculating
the direct sunlight.

If you are going to perform static simulations (i.e. choosing a certain
date and time of the year), I would just use RTRACE program (I think Axel's
Radiance Cookbook has all the info you need to start doing all this). HINT:
You can use the XFORM "-m" option for transforming your model into a
completely black world.

If you are going to perform climate-based daylight simulations, well...
everything gets messier and requires a longer explanation. I would start by
going through the first couple of tutorials in the website in order to
understand how Radiance works.

Final comment + disclaimer: I am the developer of Groundhog, so I would use
that tool in order to create the model within SketchUp and export it to
Radiance. *However, I have not ever used another tool, so there may be
better ones out there.*

Kind regards

Germán

···

2017-07-08 11:56 GMT-04:00 Andrea Laenens < [email protected]>:

Dear,

I am a student at the KULeuven and currently working on a master thesis
about estimating the health effects of daylight in a room. So far, I've
been using the program DIVA for Grasshopper (McNeel), which counts
on Radiance for light calculations. However, I am unable to retrieve the
data from it that need. I am therefore considering to dig a little deeper
into the underlying commands, and start working in Radiance instead.

The main idea for the calculation is to weigh the values of the intensity
measured inside to the spectral distribution of the light source (outside).
I would like to approach this problem using the CIE illuminants for direct
sunlight, cloudy sky and clear blue sky (as suggested by Mardaljevic et
al., 2013). As an output of Radiance, I thus expect:
- illuminance values inside, resulting from direct sunlight only
- illuminance values inside, resulting from cloudy sky only
- illuminance values inside, resulting from clear blue sky only
- or, a way to retrieve the contribution of clouded/clear sky to the light
coming from the sky dome, using a sky cover coefficient

Before I start my adventure in Radiance, I would like to know:
- is it possible to retrieve this kind of data from Radiance?
- how would you suggest doing this?

Thanks in advance,
Kind regards,

Andrea Laenens

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