Re: [EnergyPlus_Support] Evaluation Sunshading device

["Michael J. Witte" <mjwitte@xxxxxxxx>]

The modeling of surface:shading:attached is very simple compared to the model 
for Material:WindowBlind.  Shading surfaces can shade, and they can reflect.  
There is no heat balance on shading surfaces.  Shading surfaces are generally 
only useful on the exterior; I assume that is where your are modeling this.  
External shading surfaces do not block the wind imposed on the exterior surface 
of the window, but exterior blinds do alter the exterior window convection 
coefficient.  The only result I would expect to be comparable between these two 
approaches would be the transmitted solar through the window.

Mike


On 6 Apr 2007 at 17:22, sofie_mols wrote:

> Hello everyone,
> 
> I am doing research on sunshading devices and I am facing some
> problems. I have developed a preprocessor that builds a solar shading
> device with slats using the Surface:Shading:Attached model to define
> the slats as individual surfaces. I would like to compare the results
> of my sunshading with the results I get from the Material:Window:Blind
> object to simulate venetian blinds. All the dimensions in both objects
> are similar, yet the inside temperatures resulting from the two models
> differ 1 to even 2°C. Running through the engineering reference I
> can't really find what causes this difference:
> 
> 1.could it be that in the Surface:Shading:Attached model the surfaces
> are subdevided in multiple nodes to calculate the reflections, so the
> reflections from this model are more accurate as the ones from
> Material:Window:Blind?
> 
> 2. In the Material:Window:Blind object E+ takes the air gap between
> the solar shading and the glass into account, which causes a
> convection airflow and results in higher solar gains and this is not
> the case in the Surface:Shading:Attached model?
> 
> Thanks in advance for your help!
> 
> Sofie Mols
> 
> 
> 
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> 
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> 
> 
> 
> 
> 


========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx





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