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Re: [EnergyPlus_Support] Modelling of exterior fixed louvres
Modeling as Surface:Shading:Attached is certainly the most accurate approach.
If this occurs on only one window, the computing time should not be ridiculous.
If the same configuration occurs many times around the building, then it might
be a problem. When using this approach, the default action of EnergyPlus is to
mirror every shading surface, so that you do not have to worry about the facing
direction of the shading surfaces. This is necessary because surfaces in
EnergyPlus only cast shadows in one hemisphere (in the direction of the outward
facing normal).
If computing time becomes an issue, you can use the diagnostics command to turn
off this mirroring: DIAGNOSTICS,DoNotMirrorDetachedShading;
But if you do this, you *must* make sure that the azimuth and tilt of the slats
is facing down and toward the window.
Also, if the slats are light colored, you should turn on reflections using the
solar distribution field in the BUILDING object. And you can specify the
reflectance properties using Shading Surface Reflectance objects.
The approximate alternative would be to treat this as an exterior blind with
large slats. See MATERIAL:WINDOWBLIND and WindowShadingControl.
Mike
On 10 Sep 2007 at 23:59, josh_miarch wrote:
> I'm wondering about the best approach to take to model a shading
> device of the following composition:
>
> -consists of ~20 fixed louvres that span the width of the window.
> -louvres are arranged on a slope, such that the uppermost louvre at
> the top of shading device is closer to the window face (237mm from the
> window face at a height level with the window head) than the louvre at
> the base of the sunshade (986mm from the window face at a height of
> 529mm above the window sill)
> -louvres between the uppermost and lowermost louvres are spaced evenly
> and linearly.
>
> My questions are:
>
> 1. Should I simply model in the geometry of the shades directly and
> use Surface:Shading:Attached, or will that result in a ridiculous
> amount of processing time?
> 2. Are there any ways to approximate the effect of a shading device
> like this that won't excessively compromise the accuracy of the
> simulation?
>
> Thanks a lot,
>
> Josh
>
>
>
> Josh Kjenner, EIT, LEED AP
> Manasc Isaac Architects Ltd.
> 10225 100 Avenue :: Edmonton, AB T5J 0A1
> 780.429.3977
>
>
>
>
>
>
> The primary EnergyPlus web site is found at:
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>
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>
> Attachments are not allowed -- please post any files to the appropriate folder
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>
> EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the
> Documentation link and press the "search" button.
>
> Yahoo! Groups Links
>
>
>
>
>
========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support
EnergyPlus-Support@xxxxxxxx
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