[Equest-users] building shade effect

[Bishop, Bill]

Bobby,

My approach would be (would have been) to model the shades as window overhangs or building shades, or a combination thereof. Based on your sketches this would be a lot of work, but the louvers are obviously an important feature for the design team and will have considerable project cost. You could try replicating the impressive things Nick Caton has done with shades per the attached email. You could try it for a floor or two to get the delta energy improvement and extrapolate for # of floors to get a rough comparison to your transmittance approach. I would think the reduction in cooling energy would be considerable if using clear glass with external shades vs. without. The overall numbers will of course depend on several other things, including the proportion of solar load to overall building cooling load.

Regards,
Bill

[cid:image001.png at 01CD3F0D.CC92CD30]<mailto:wbishop at pathfinder-ea.com>


From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Bobby Sy
Sent: Wednesday, May 30, 2012 10:19 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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120531/4db201dc/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 21646 bytes
Desc: image001.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120531/4db201dc/attachment-0002.png>
-------------- next part --------------
An embedded message was scrubbed...
From: Nick Caton <ncaton at smithboucher.com>
Subject: Re: [Equest-users] Defining Building and Fixed Shades using Coordinates	Alone
Date: Tue, 17 Apr 2012 20:56:22 +0000
Size: 817542
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120531/4db201dc/attachment-0002.eml>