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RE: [EnergyPlus_Support] thermal and optical properties calculation of facade systems
Emanuele,
Grid can be fully defined in shading layer library, so it will automatically produce right openness factor. Also, in WINDOW program you can model any gap width, including 2? 6?.
One note, defining shading layer requires solar-optical properties of the shade material, which is normally spectral data, but if you don?t have spectral data and don?t expect strong spectral dependency, you can supply broadband properties (T, Rf, and Rb). For most shade materials, T is 0, so you are really looking for Reflectance front and back only.
Charlie
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Emanuele Naboni
Sent: Thursday, February 11, 2010 8:58 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] thermal and optical properties calculation of facade systems
Hello Charlie,
I have not look at Window in its new version 6.2 yet. It seems that is worth for a try!
I am just wondering if the opening factor could be assigned form 44% to 66% and if the woven shades could be modeled as 2' 6" detached from the glass plane.
The scope of this exercise is to chose the right open factor for metal grid and prove the overall system performance.
Thank you so much for your help!
Emanuele
On Thu, Feb 11, 2010 at 2:28 PM, D. Charlie Curcija <<mailto:curcija@xxxxxxxxxxxxxxxx>curcija@xxxxxxxxxxxxxxxx> wrote:
Emanuele,
WINDOW 6.2 and THERM 6.2 actually can model shading devices of the three general types:
- Venetian blinds
- Frits
- Woven shades
Your system is closest to woven shades type, as the woven shades are modeled as a grid of vertical and horizontal weaves. While it is true that woven shades algorithm for diffuse part is developed for denser weave than you have, it is also true that diffuse portion is very small and will not significantly affect your results.
I would encourage you to try to model your system with WINDOW 6.2/THERM 6.2, because results will be much more accurate than any approximation and rule of thumb that you may use otherwise.
D. Charlie Curcija
DesignBuilder Software
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Millers Falls, MA 01349
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email: <mailto:curcija@xxxxxxxxxxxxxxxxxxxxxxxxx>curcija@xxxxxxxxxxxxxxxxxxxxxxxxx
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From: <mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:<mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Emanuele Naboni
Sent: Thursday, February 11, 2010 8:08 AM
To: <mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] thermal and optical properties calculation of facade systems
Hello Edward,
Yes, the grid is on the outside, the open area factor could varies from 44% to 66% as a function of the final product installed.
Surely the grid has an impact as a wind shelter so that the wind coefficient will be effected (I hope to find the way to use a reliable coefficient without CFD calculations).
Playing with WIS I have now that is possible to model this case too.
Thanks for the advices,
Emanuele
On Thu, Feb 11, 2010 at 1:40 PM, Edward G. Lyon <<mailto:eglyon@xxxxxxx>eglyon@xxxxxxx> wrote:
Sounds like your grid is on the outside and casts a shadow on the window. A fair approximation is to calculate the glazing alone using Window. Adjust the exterior wind coefficient if you think the grid creates some shelter for the window. The grid is just a net free area that limits the % of sun light that reaches the glass. Most of your light transmittance properties are simply the % of calculated values. Things can be more complex if the grid is almost opaque, and you may need to use CFD for air movement and calculate grid/glass reflections separately.
Having the grid inboard of the glass is also more complicated because of reflections and absorption that are not as simple as just shading the glass from the outside.
Ned Lyon, P.E. (MA)
Staff Consultant
SIMPSON GUMPERTZ & HEGER
781.907.9000 main
781.907.9350 direct
781.907.9009 fax
<http://www.sgh.com>www.sgh.com
From: <mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:<mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Emanuele Naboni
Sent: Thursday, February 11, 2010 5:04 AM
To: <mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] thermal and optical properties calculation of facade systems
Dear All,
Does any of you have an idea on what software tools could be used to calculate thermal and optical transmission properties (e.g., thermal transmittance, total solar energy transmittance) of a complex window system based on the ISO 15099:2003 method?
The system that I am trying to study is composed by a double pane glass protected by a vertical metal grid which is 750mm (2' 6") detached from the window.