radiance

Hello Everyone,

I am involved in the simulations of interior Venetian blinds in a
10' wide, 18' long and 10' high
office room with one 6 ' by 6 ' window placed on the south
oriented wall. The window sill height is 3'.

I am observing that the illuminance levels inside the room (at the
sensor point close to the window) are higher with the interior
Venetian blinds placed in the model (4500? lux) as compared to the
model without the blinds (3000 ?lux).
Also even though the illuminance levels are much higher (at the
level of 4500 lux close to the window) there is no glare index
observed (that is value of Daylight glare index DGI is equal to
zero).

I am attaching a compressed file folder containing all the input
files and the octree files. I might sound very naive to you,
please excuse me for any ignorance on my part, I am very new to
the Radiance as well as UNIX. I have used the PICO text editor as
vi text editor was having some problems in my system. There is a
file named command, in the folder attached, it has all the
commands that I have used in compiling and generating different
components of the model. finalmultiplesim1.csh is the shell script
used and January.out is the output file.

I would appreciate some suggestions as to where I might be going
wrong with the simulations.

Thank you.

command (115 Bytes)

Desk1.rad (1.7 KB)

Desk2.rad (1.71 KB)

finalmultiplesim1.csh (527 Bytes)

Mainblinds.rad (23.7 KB)

mainsamples.inp (84 Bytes)

newglares.csh (265 Bytes)

outside1.rad (168 Bytes)

sky.rad (353 Bytes)

window.rad (141 Bytes)

simulation.oct (15.9 KB)

room.rad (1.94 KB)

I've just had a quick look at your files. At the sky condition that
you've included in the files I'd say that the sunbeam through the
window misses the sample point (therefore no direct component).
If you have the blinds down you get some reflected sunlight at
the sample point which increases the illuminance.

I have to play around with your scene a bit to confirm this but
from an initial rendering this seems to be the case.

Can't comment on the glare issue.

Regards,
Thomas

···

On 27 Nov 2008, at 04:52, G V DEEPAK wrote:

Hello Everyone,

I am involved in the simulations of interior Venetian blinds in a
10' wide, 18' long and 10' high
office room with one 6 ' by 6 ' window placed on the south
oriented wall. The window sill height is 3'.

I am observing that the illuminance levels inside the room (at the
sensor point close to the window) are higher with the interior
Venetian blinds placed in the model (4500? lux) as compared to the
model without the blinds (3000 ?lux).

I've noticed that you have boxes ('tables') in your room that are
exactly the same height as your sample points (0.75m). Please
lift your sample points (or lower the desks) by a small amount
(0.01m is enough). When a point for rtrace calculation is located
on a surface (as in your case) the results are not predictable.

Raising the points slightly above the surface will not influence
your illuminance values but it will provide reliable results.

I'd say it is quite unusual to do an illuminance calculation with
a horizontal orientation directly on a surface. Effectively you are
blocking half of the hemisphere with your table surface. I would
run all the calculations without the desks in the scene to see if
that makes a difference.

Regards,
Thomas

···

On 27 Nov 2008, at 04:52, G V DEEPAK wrote:

Also even though the illuminance levels are much higher (at the
level of 4500 lux close to the window) there is no glare index
observed (that is value of Daylight glare index DGI is equal to
zero).

Hello Thanks for you prompt reply.. I tried the simulations by removing the desks placed.. but it does not seem to make much of a difference.

About the sky condition, Is there something wrong with the sky condition, I mean do I need to change anything in it ?

Thank you

···

On Thu Nov 27 07:15:36 EST 2008, Thomas Bleicher <[email protected]> wrote:

On 27 Nov 2008, at 04:52, G V DEEPAK wrote:

Hello Everyone,

I am involved in the simulations of interior Venetian blinds in a
10' wide, 18' long and 10' high
office room with one 6 ' by 6 ' window placed on the south
oriented wall. The window sill height is 3'.

I am observing that the illuminance levels inside the room (at the
sensor point close to the window) are higher with the interior
Venetian blinds placed in the model (4500? lux) as compared to the
model without the blinds (3000 ?lux).

I've just had a quick look at your files. At the sky condition that
you've included in the files I'd say that the sunbeam through the
window misses the sample point (therefore no direct component).
If you have the blinds down you get some reflected sunlight at
the sample point which increases the illuminance.

I have to play around with your scene a bit to confirm this but
from an initial rendering this seems to be the case.

Can't comment on the glare issue.

Regards,
Thomas

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Radiance-general mailing list
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G V DEEPAK
Graduate student and Research Assistant
M.E. Rinker, Sr. School of Building Construction.
University Of Florida.

I don't think so. I was just explaining why you might see get higher
illumination values with the blinds down.

Regards,
Thomas

···

On 27 Nov 2008, at 19:31, G V DEEPAK wrote:

About the sky condition, Is there something wrong with the sky condition, I mean do I need to change anything in it ?

Hello Everyone,

Thanx again Dr Bleicher, Assuming that the blinds are used to block the sunlight coming inside, then why is it that the blinds in my model are not blocking the sunlight coming in ? is there any problem with my model..? I would really appreciate if some one could help me out with this problem.

Thank you.

···

On Thu Nov 27 16:38:09 EST 2008, Thomas Bleicher <[email protected]> wrote:

On 27 Nov 2008, at 19:31, G V DEEPAK wrote:

About the sky condition, Is there something wrong with the sky condition, I mean do I need to change anything in it ?

I don't think so. I was just explaining why you might see get higher
illumination values with the blinds down.

Regards,
Thomas

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

G V DEEPAK
Graduate student and Research Assistant
M.E. Rinker, Sr. School of Building Construction.
University Of Florida.

It's just Mr me.

Your blinds are fine but the bright material reflects a lot of the
sun light (direct, very bright) to the ceiling. I've rendered an
image of the scene here:

The additional illumination is - I think - caused by the light
reflected from the blinds to your sensor point. Without blinds
there is just the part of the sky you can see from the sample
point (no sun for the sky condition shown). With blinds the
sunlight is reflected diffusely at the blinds and a lot of sun light
is redirected to the sensor point that has not been there before.
Because the blinds are bright white this exceeds the light of
the sky dome so you get higher illumination values.

I haven't had time yet to do a renderings without blinds to
confirm this.

This might also explain why you get negative values for your
glare index. I'm no expert but AFAIK the glare index is calculated
from local hot spots. With your blinds there are no hot spots because
the whole window is uniformly bright. You can look into this year's
workshop presentations on glare from daylight by Jan Wienold:

http://www.radiance-online.org/radiance-workshop7/

You have to contact him directly about a copy of 'evalglare'. The
link in the presentation still does not work ...

Regards,
Thomas

···

On 28 Nov 2008, at 19:23, G V DEEPAK wrote:

Hello Everyone,

Thanx again Dr Bleicher, Assuming that the blinds are used to block
the sunlight coming inside, then why is it that the blinds in my model
are not blocking the sunlight coming in ?