Curtainwall, ASHRAE U-value

2 posts / 0 new
Last post

Hi all,

I am trying to figure out whether the maximum U-value for curtain wall ( 0.35) stated in ASHRAE 90-1.2007 accounts for spandrel glass? ASHRAE defines fenestration as " all areas that let in block walls". Should we treat spandrel as frame type wall?

Your thoughts and suggestions are appreciated.


Ana N.'s picture
Joined: 2011-09-30
Reputation: 0

Hi Ana,

I think this will depend on whether the spandrel glass is part of a wall or
not. I have seen cases where it clearly is, like when there is insulation
and other wall components behind it and the spandrel is simply being used to
make the exterior of the building look like it's all glass. The U-value in
this case would be calculated as with any exterior wall composition. I have
also seen it used as a top lite or a side lite of a curtain wall window
system, in which case the maximum U-value for curtain wall would apply.

Happy New Year!


cmg750's picture
Joined: 2010-10-05
Reputation: 0