[Equest-users] building shade effect

[Michael Wilson]

While I wouldn’t expect big savings from the shades, I think it might be a
bit higher than what you’re seeing because of the way its modelled. Using
proportional transmittance doesn’t account for how the shading varies with
sun angle. When the sun is high, less solar will get through. As Bill says,
I would model this as a building shade, actually putting each louver in. It
looks like the louvers are tubular, so you can probably approximate that
with a vertical shade and another one at 45°. 

 

While this sounds like a lot of work, if you use copy and paste in the inp
file it probably isn’t as bad as it sounds. Just need to change the z
coordinate once you’ve put the first ones in. You might consider doing it in
Excel, with a formula for the z, and then copying the results into the inp
file. That would be pretty quick.

 

Mike

 

Michael Wilson, P.Eng., Enerficiency Consulting

PO Box 1911 - 458 Abbs Rd., Gibsons, BC  V0N 1V0    |    604-886-9864    |
www.enerficiency.ca

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Bobby Sy
Sent: May-30-12 7:19 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] building shade effect

 

Hello everyone!

 

I am working on a project, a high rise office building. The architect added
louvers as part of the design which I admire for sophistication. Attached is
a picture that shows the louvers outside for shading. But, when I did the
initial run, the effect of the louvers is only around 1% energy improvement
from the baseline.

 

Please let me know if there is a better way to do it in eQuest. What I did
was to measure the louver thickness and proportioned it to the glass area
that it covers. I put the fraction as "Transmittance:" in Building and Fixed
Shades properties. Doe 2 help says: 


TRANSMITTANCE


Fraction of incident solar radiation that is transmitted by the shading
surface. The default value is 0.0, which means the surface is opaque. A
value greater than 0.0 represents a device that passes some solar radiation,
such as a tree, lattice, or fabric. Using SHADE-SCHEDULE allows seasonal
variation in transmittance. Daylighting calculation assumes TRANSMITTANCE =
0.

 

The design team quite find it hard to believe that the louvers have very
minimal effect. I told them to consider the window to wall ratio (almost
60%) and that fact that they will be using a clear glass, even with these
louvers partial UV rays still pass through the gaps that spreads allover the
glass surface that adds to the heat load for air conditioning. Ive noticed
to some of my other projects in tropical countries, building shades don't
have much effect to energy efficiency. Did anyone encounter the same result
with building shades? 

 

 

Thanks,

 

Bob

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