Exterior Shades

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Hi All,
My Glazing is having exterior shade from all four side it
is like 2 overhangs one at top and other at bottom of glazing and two
side fins. is this any formula to calculate reduction in shgc value
by all four shades as it is just by one overhang.


sambhav tiwari's picture
Joined: 2011-09-30
Reputation: 0

There is no standard formula for doing this. A correction factor for the SHGC could be calculated, but this factor would change significantly depending on geographic location (sun angles), and would not give you accurate results at an hourly level (accurate for annual only). If you're trying to avoid modeling all of the shades, you could pick one typical window for each exposure to model, and apply those results to all of them, but I'd recommend against that.

This is when modeling geometries in Revit comes in handy ;)

Greg Collins

Greg Collins's picture
Joined: 2011-09-30
Reputation: 0


I find that the overhang and left/right fins allowed for each window
take care of most of shading I encounter. You can use building shades
for anything else. Building shades might even make more sense if you
have a single continuous overhang that shades several windows, or if the
shade is non-opaque.



Bishop, Bill2's picture
Joined: 2011-09-30
Reputation: 0

Little-known (?) factoid that may help:

In detailed mode after wizards, you can define a "setback" for one or
any # of windows. This achieves 4-sided shading for both the window and
frame, as you're describing ;). I don't think this shows up I the 3D
view, but it could be my current project is just acting wonky.

PS: Bill, I think you may be a little off on your rooftop unit
dimensions there... let's not set a sloppy example ^_^ (j/k)! Awesome
as usual!



Nick-Caton's picture
Joined: 2011-09-30
Reputation: 805