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Joel McKellar, Assoc. AIA, LEED AP
Senior Member
Username: joelmckellar

Post Number: 17
Registered: 02-2006
Posted on Tuesday, February 12, 2008 - 05:18 pm:   Edit PostDelete PostPrint Post

What should I be looking for when specifying sunshades for curtain walls? I've found a few companies that integrate sunshades into their systems (Kawneer, EFCO, Wasau, and YKK).

I'm no engineer, but looking at the details none seem extremely secured to the walls. Are there any performance standards to reference? Details to watch out for?

Thanks,

Joel
Phil Kabza
Senior Member
Username: phil_kabza

Post Number: 303
Registered: 12-2002
Posted on Saturday, February 16, 2008 - 10:21 pm:   Edit PostDelete PostPrint Post

The obvious advantage of specifying a sunshade that is integrated with a curtain wall system is the comprehensive engineering. Otherwise, you'd have to engineer attachment to the structure, and deal with wind loading and seismic design loading - complex, and not something your project structural engineer looks forward to.

The other challenge for stick built sunshades is how they are to attach to the building structure. They're going to be a air- and moisture-barrier penetration, as well as a thermal envelope anomaly. Plus a great opportunity for bi-metallic corrosion. I guess you can tell how enthusiastic I am about these ...
Anonymous
 
Posted on Saturday, February 16, 2008 - 11:23 pm:   Edit PostDelete PostPrint Post

Uneven shading or shadows on glass or glazing can lead to uneven temperatures of the glass which in turn can lead to spontaneous thermal breakage. Shutters or screens or canopies have to be properly designed to avoid these uneven thermal conditions on the curtain wall.
Bill Coady CSI, CCPR
Intermediate Member
Username: billcoady

Post Number: 4
Registered: 06-2006
Posted on Monday, February 25, 2008 - 07:37 pm:   Edit PostDelete PostPrint Post

I'd like to add to "anonymous'" statement about thermal stresses on the glass. While the shutters/screens/canopies should be designed properly of course, it is important that the glass be analyzed for thermal stresses to determine if it needs to be heat treated. There are a few rules of thumb about when to heat treat for thermal stress but it is better to be safe and have an analysis completed. Most fabricators and glass manufacturers will do this at no charge on a project specific basis.
Steven Bruneel, AIA, CSI-CDT, LEED-AP
Senior Member
Username: redseca2

Post Number: 84
Registered: 12-2006
Posted on Tuesday, February 26, 2008 - 12:59 pm:   Edit PostDelete PostPrint Post

I am familiar with an un-named large renovation project where sunshades were added to the exterior to allow the existing single monolithic pane glass to remain while meeting modern energy efficiency requirements.

The issue of spontaeous thermal breakage was not considered by the design team and only came up during job walks by design-assist bidders.

Now the project has replacement glass in the scope and has kept the sunshades, more as a decorative feature than originally intended however.

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