[Equest-users] building shade effect

Nick Caton ncaton at smithboucher.com
Thu May 31 07:16:54 PDT 2012

Feeling confident in your modeling approach is very much important, but before running deep into alternate methods, I would seek perspective on what % improvement is even feasible.  Perhaps a 1% net improvement is quite impressive, all things considered?  Considering static shades can be simultaneously helpful and harmful thermally over a year, a few iterations exploring different transmittance values may be enlightening.

Doing so, you might be able to establish a ceiling for maximum possible improvement with such shades, and suggest a more optimized exoskeleton spacing or similar.

There may also be a lesson in here about how to present results in a fashion that both informs and appeases the design team.  Perhaps the shades may not have an impressive net annual baseline % improvement, but significant thermal comfort and glare issues are averted, and cooling plant capacities can be lowered by slicing the summertime solar loads.... I would also caution to check the solar loads are indeed cutting down as anticipated if you aren't sure of your approach.

Best of luck!


[cid:489575314 at 22072009-0ABB]


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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Umesh Atre
Sent: Thursday, May 31, 2012 8:30 AM
To: Bobby Sy; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] building shade effect

What is the project location and how is the building oriented? Do these louvers run across the entire height of the building?
If you have a heavily internal load dominated (office) building, the building skin effect might be minimal, but then again the shading design
you have in this project looks pretty dense and assuming you have a need for cooling, my gut feeling is that 1% is on the lower side.

From: equest-users-bounces at lists.onebuilding.org<mailto: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<mailto: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:

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?


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