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

[David Bradley <bradley@tess-inc.com>]

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

heloise.pelen@etamine.coop 75 rue de la Villette - 69003 Lyon Std : 04 37 45 34 20 / Fax : 04 37 45 41 38 Ld : 04 37 45 34 13

Visitez notre nouveau site web : www.etamine.coop !

 

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