[Radiance-general] Daylight factor

[Christopher Rush]

You have the same -B 0.558659 in both the daylight factor and
illuminance calculations. I'm afraid I can't help much more, as I'm not
sure what Ecotect does with the data that comes out of your Radiance
process.

 

Also, I'm still not sure what command you're actually using to generate
your data results.

 

-Chris

 

From: radiance-general-bounces at radiance-online.org
[mailto:radiance-general-bounces at radiance-online.org] On Behalf Of
Victor Li
Sent: Saturday, December 12, 2009 11:29 PM
To: Radiance general discussion
Subject: Re: [Radiance-general] Daylight factor

 

Thank you very much!

Actually i uesed ECOTET exported to DESKTOP RADIANCE to calculate. The
only differernce between Daylight factor and Illuminance calculation is
the -B 0.558659 definition in 11_SKY.RAD 
In Daylight factor calculation the sky is defined as following:

!gensky 12 21 12.00 -c -a 31.400 -o -121.400 -m -120.000 -B 0.558659 |
xform -rz -27.000

skyfunc glow sky_mat
0
0
4
     1 1 1 0

sky_mat source sky
0
0
4
     0 0 1 180

skyfunc glow ground_glow
0
0
4
     1 .8 .5 0

ground_glow source ground
0
0
4
     0 0 -1 180

In Illuminance calculation, the definition is :

!gensky 12 21 12.00 -c -a 31.400 -o -121.400 -m -120.000 -B 0.558659 |
xform -rz -27.000

The rest is all the same.

For converting the output, the ECOTECT can convert it automatically.



2009/12/11 Christopher Rush <Christopher.Rush at arup.com>

What are the dimensions and resolution of your grid in 11.pts compared
to the full boundary of your scene (including ground plane and anything
else) in 11.oct? Maybe -ar is not high enough.

 

What is your sky definition going into 11.oct?

 

Do you have an rcalc command to convert the output in 11.dat?

 

 

 

From: radiance-general-bounces at radiance-online.org
[mailto:radiance-general-bounces at radiance-online.org] On Behalf Of
Victor Li
Sent: Thursday, December 10, 2009 8:34 PM
To: Radiance general discussion
Subject: Re: [Radiance-general] Daylight factor

 

The rtrace setting is "rtrace -I -h -dp 2048 -ar 32 -ms 0.063 -ds .2 -dt
.05 -dc .75 -dr 3 -sj 1 -st .01 -ab 8 -aa .1 -ad 512 -as 256 -av 0.01
0.01 0.01 -lr 12 -lw .0005  -af 11.amb 11.oct < 11.pts > 11.dat"  And
the two calculations of daylight factor and illuminance are all the same
settings. What do you think?

2009/12/10 Christopher Rush <Christopher.Rush at arup.com>

It would help to know your command process for calculating illuminance
and daylight factor to troubleshoot.

 

Also, if your rpict/rtrace ambient sampling settings are not stringent
enough, differences could be due to random sampling variation between
two different calculation runs.

 

From: radiance-general-bounces at radiance-online.org
[mailto:radiance-general-bounces at radiance-online.org] On Behalf Of
Victor Li
Sent: Thursday, December 10, 2009 4:04 AM
To: Radiance general discussion
Subject: [Radiance-general] Daylight factor

 

Dear:

Daylight factors are expressed as the percentage of natural light
falling on a work surface compared to that which would have fallen on a
completely unobstructed horizontal surface under exactly the same sky
conditions. Thus, a daylight factor of 5% on an internal surface means
that it received only 1/20th of the maximum available natural light.

so we can calculate daylight factor by RADIANCE with a overcast sky.
Then i calculated the illuminance under overcast sky. I found the
distribution of illuminance and skyfactor in the room is different. For
example, in the room ratio of minimum to average of daylight and
illuminance are quite different. Would you tell me the reason?

Best Regards!

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