[TRNSYS-users] Type 34 for non-vertical windows

[David Bradley]

Héloïse,
  I don't think Type34 is going to work for non-vertical windows; it 
contains an analytical solution for the view factor between a vertical 
surface, the horizontal ground and a horizontal overhang. In the case of 
a non horizontal overhang, we take the horizontal projection of the 
overhang. That view factor calculation isn't going to be correct for a 
non-vertical surface. You might consider using Type67 which allows you 
to define a shading mask but that component calculates shading from the 
center of glass and so ignores the effect of the window's slope.
Best,
 David


Heloise PELEN wrote:
>
> Dear TRNSYS users,
>
>  
>
> I am currently working on a project which involves non-orthogonal 
> windows, shaded by horizontal overhangs. I'd like to use type 34 to 
> model these overhangs. My windows have different slopes, from 30° to 
> 80° with the horizontal direction.
>
>  
>
> 1.     Type 109, from which the radiation inputs of type 34 come, uses 
> the slope of my tilted windows to compute the beam radiation and the 
> incident angle of direct radiation on this non-orthogonal surface. Is 
> it enough to tell type 34 that my windows are not orthogonal ? Indeed, 
> the description of the 1^st parameter of type 34 reads: "Type34 
> assumes a vertical orientation for the window." The problem is that, 
> my window not being vertical, an overhang doesn't have the same impact 
> than if the window was vertical, since the window is closer to the 
> sun's zenith angle.
>
>  
>
> 2.     What length of overhang projection and overhang gap should I 
> consider ? Mark Duffy's answer on Fri Dec 11^th 2009 suggests that we 
> should take the horizontal distance for the overhang projection, but 
> is this right even in this case, with a non vertical window ? Should I 
> take instead the distance in the orthogonal direction from the window 
> to the end of the projection ?
>
>  
>
> Thanks for your help.
>
>  
>
> Best regards,
>
>  
>
> *Héloïse Pelen*
>
> *ETAMINE*
>
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>
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>
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>
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>
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Thermal Energy System Specialists (TESS), LLC 
David BRADLEY                      22 N. Carroll Street - Suite 370 
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