# perforated lamellas

Hi all,
does anybody knows how I can simulate perforated curved aluminum
lamellas? Which material is recommended to get plausible values (for
reflection (on aluminum and transmission (through the gaps) by using a
sunny and overcast sky in my simulation model? The result should be the
illuminance level and respectively Daylight factor inside.
The lamellas are just rotatable but not movable, the perforation is
fixed with 15% (whitout knowing exactly the design of the longish small
holes) and should be used like lightshelves in front of heat-protection
glass.

Thanks for help!

Friedemann Kik
[email protected]

Hi Friedemann,

I was hoping someone else who knew more about this material might respond, but maybe no one does...

If you want an accurate model of this material, you need to use the geometric cross-section and the material properties to create an analytic estimate of the integrated light transfer. In other words, it ain't easy. Better still, you would obtain measurements of the angular transmission of the material, but this poses an even greater challenge.

A couple of years ago, Visarc hired me to create a mathematical model of transmission through a grid structure, simulated as rectangular holes in a diffuse structure. The associated calculation is contained in grating.cal in the standard distribution. If your holes are oval rather than rectangular, this won't be as accurate, but it might be a start. If your surface is specular and you wish to capture the change in specular reflectance with angle, more work is needed.

-Greg

···

From: "Friedemann Kik" <[email protected]>
Date: October 27, 2006 8:20:37 AM PDT

Hi all,
does anybody knows how I can simulate perforated curved aluminum lamellas? Which material is recommended to get plausible values (for reflection (on aluminum and transmission (through the gaps) by using a sunny and overcast sky in my simulation model? The result should be the illuminance level and respectively Daylight factor inside.
The lamellas are just rotatable but not movable, the perforation is fixed with 15% (whitout knowing exactly the design of the longish small holes) and should be used like lightshelves in front of heat-protection glass.

Thanks for help!

Friedemann Kik
[email protected]

Wouldn't the transmission and distribution vary depending on the angle of the lamellas? These are like perforated metal mini blinds right?

Mark

Yes, the angle of the holes would matter. I had assumed they were perpendicular to the material face, but as I said, I know nothing about this device.

-G

···

From: "Mark de la Fuente" <[email protected]>
Date: October 31, 2006 6:44:36 AM PST

Wouldn't the transmission and distribution vary depending on the angle of the lamellas? These are like perforated metal mini blinds right?

Mark

Friedemann,

I assume you only try to approximate the effect on the shadowing
of the room, then, not modelling the real reflectance of the material.

materials in the distribution) and add a mixfunc with void as second
modifier. Thus the areas defined in the function file should simply
be transparent like a hole in the material.

There was a function file that created a dot pattern by Georg
Mischler; I just can't remember the name now. You have to specify
the right dimmensions of the dots for your 85/15 ratio. I think
you could apply a scale to it so that it created oval dots instead of
circles (but that might have been a different function file).

hth,
Thomas

···

________________________________

From: [email protected] [mailto:[email protected]] On Behalf Of Friedemann Kik
Sent: 03 November 2006 08:42

Hi all,
I agree, but my simulation should give results for LEED minimal requirements. There it is only one defined sky (midday, equinox, clear sky) and a minimum average illuminance in the room behind the facade (+ turnable but not moveable lamellas) is required.
The lamellas I've to simulate are not the perforated mini blinds, but get a dimensions of 0.5 meter width and a length of about 3 meters.
The surface is brushes aluminum (adapted for redirect the daylight into the room).
With this starting position, I need a material definition which reflect the daylight (direct and diffuse) at 85% of lamella area and, on account of the 15% of gaps in the lamellas, a light transmission of 15%.
Does anybody have an idea?

Thanks
Friedemann

-----Ursprüngliche Nachricht-----
Von: [email protected] [mailto:[email protected]] Im Auftrag von Mark de la Fuente
Gesendet: Dienstag, 31. Oktober 2006 15:45
An: [email protected]

Wouldn't the transmission and distribution vary depending on the angle of the lamellas? These are like perforated metal mini blinds right?

Mark

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Friedemann,

I was going to suggest the perforate.cal file as well.

Check out:

Good luck.

Mark

···

________________________________

From: [email protected]
[mailto:[email protected]] On Behalf Of
Friedemann Kik
Sent: 03 November 2006 08:42

Hi all,
I agree, but my simulation should give results for LEED minimal
requirements. There it is only one defined sky (midday, equinox, clear
sky) and a minimum average illuminance in the room behind the facade (+
turnable but not moveable lamellas) is required.
The lamellas I've to simulate are not the perforated mini blinds, but
get a dimensions of 0.5 meter width and a length of about 3 meters.
The surface is brushes aluminum (adapted for redirect the daylight into
the room).
With this starting position, I need a material definition which reflect
the daylight (direct and diffuse) at 85% of lamella area and, on
account of the 15% of gaps in the lamellas, a light transmission of
15%.
Does anybody have an idea?

Thanks
Friedemann