Aluminum infill panel behind the glass

8 posts / 0 new
Last post

Hello all,

Attached is a part of wall section of the proposed model of office building
anticipated LEED silver certification.

8-43 is Alum. Curtain wall system (KAWNEER CLEARWALL) fritted pattern on #2
clear glazing surface and painted spandrel on #4 clear glazing (U-0.48,
SHGC-0.39) and 8-45 is Aluminum infill panel with 2? rigid insulation.

I am assuming this part as spandrel glass in the proposed model. How can I
add the effect of 8-45 that is behind the glass?

I would appreciate your comments.

Morteza

[image: Inline image 1]

Morteza Kasmai's picture
Offline
Joined: 2011-09-30
Reputation: 0

Since the insulation is not continuous, the overall effect of adding
this insulation is minimal. 2D or 3D thermal analysis would be needed
to come up with the best estimates, but the CEC also includes in thier
Standards Joint Appendix (JA) some reasonable estimates; see Table 4.3.8
and related equations.

Here is a link to the 2013 CEC Standards site:
http://www.energy.ca.gov/title24/2013standards/rulemaking/documents/final_rulemaking_documents/44_Final_Express_Terms/
I don't think any of this changed from 2008 -> 2013.

David

--

David Reddy

David Reddy4's picture
Offline
Joined: 2012-03-30
Reputation: 0

Spandrel isn't vision glazing and should not be modeled as a "window". It is a particular opaque wall type that should be modeled as a wall. The only difference is that instead of having a brick, EFIS, stone, metal panel, etc., the exterior surface in a spandrel wall assembly is glass.

Tim.

Timothy Howe, MS, BEMP, LEED? AP BD+C

Howe, Timothy's picture
Offline
Joined: 2011-09-30
Reputation: 0

Many thanks Tim,

I cannot select any table in ASHRAE appendix A for this type of wall. How
can I select U-factor for this wall?

Regards,

Morteza

Morteza Kasmai's picture
Offline
Joined: 2011-09-30
Reputation: 0

I also have modeled opaque elements like this as distinct wall constructions more than once for LEED without issue.

I believe spandrel glass systems typically fall squarely into the glossary definition of "wall --> steel framed." Review the glossary terms to be sure and decide if instead the "Wood framed/other" envelope category is a better fit.

~Nick

[cid:489575314 at 22072009-0ABB]

NICK CATON, P.E.

Nick-Caton's picture
Offline
Joined: 2011-09-30
Reputation: 805

An HTML attachment was scrubbed...
URL:

Aaron Smith's picture
Offline
Joined: 2011-09-30
Reputation: 0

Aaron,

Thank you for your response. You are right; I check with the architects,
they are using ?Kawneer 1600?. I input the data in Frameplus Online and it
gives me U-0.48 for the glass and U-0.20 for the total spandrel with 2?
insulation.

Assuming the spandrel system as steel wall, per Nick?s suggestion (Thanks
Nick), per ASHRAE Table A3.2, assembly U-factor for this wall is 0.113.
Unfortunately, both options indicate U-factors that are greater than the
U-factor of the baseline model (U-0.064 for zone 4A) and reduce the total
energy savings for the project. Am I right in selecting U-factors?

I truly appreciate your help,

Morteza

Morteza Kasmai's picture
Offline
Joined: 2011-09-30
Reputation: 0

An HTML attachment was scrubbed...
URL:

Aaron Smith's picture
Offline
Joined: 2011-09-30
Reputation: 0