[Bldg-sim] Glas Curtain Wall - Appendix G

[Leonard Sciarra]

Matthew, 
If the clear glass, vision glass, daylight glass or whatever is greater
than 40% reduce it proportionally to 40% and use the prescriptive 90.1
chapter 5 values.  For the remainder of the building (opaque portions)
you then use (for U-factor) the 'steel framed' wall values.
                                                    
Leonard Sciarra, AIA, LEED(r) ap
Associate
312.577.6580  Direct
312.456.0123  Main
leonard_sciarra at gensler.com <mailto:leonard_sciarra at gensler.com> 
                                                     
Gensler
30 West Monroe
Suite 400
Chicago, Illinois 60603
USA 
 

________________________________

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Michael
Rosenberg
Sent: Thursday, February 14, 2008 1:33 PM
To: Higgins, Matthew
Cc: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Glas Curtain Wall - Appendix G


Matthew,
 
I think what you need to do is pull the opaque portion of the curtain
wall out. If the remaining glazing fraction is above 40%, than that
portion needs to be reduced in you baseline model. 
 
Mike
 
Michael Rosenberg
Oregon Department of Energy
625 Marion St. N.E.
Salem, OR 97301-3742
Phone : (503) 373-7809
Fax: (503) 373-7806

>>> Matthew Higgins <higgins at edi-arch.com> 2/14/2008 10:29:05 AM >>>

Michael - I assume you saw my previous post? (Below).... What I am
wondering is how LEED/ASHRAE 90.1-2004 Appendix-G treats glass curtain
walls in baseline models: either as a curtain wall with 90.1
climate-specific glass properties or if I need to reduce the amount of
glazing to 40% (the prescriptive maximum Window/Wall ratio).

Your thoughts?

*PREVIOUS POST*

Has anyone modeled, submitted, and certified a LEED building with a 
glass curtain wall?

I ask because I am wondering how to treat the curtain wall in the 
baseline model. I've tried two scenarios thus far and there is a 10% 
consumption difference between them. The only thing that differs between

the two is that the lower consuming model has a 40% window-to-wall area 
where the other is still a glass curtain wall, but using Appendix G 
window properties. And to put this in perspective the curtain wall is 
facing NNE and is 3 stories high.

I would also truly appreciate any reference to a LEED CIR regarding this

issue, if there is one.

Matthew Higgins, LEED AP
Technical Specialist
Environmental Dynamics, Inc.
Architecture and Sustainability Consulting Services
505.242.2851



Matthew Higgins wrote:

>Has anyone modeled, submitted, and certified a LEED building with a 
>glass curtain wall?
>
>I ask because I am wondering how to treat the curtain wall in the 
>baseline model. I've tried two scenarios thus far and there is a 10% 
>consumption difference between them. The only thing that differs
between 
>the two is that the lower consuming model has a 40% window-to-wall area

>where the other is still a glass curtain wall, but using Appendix G 
>window properties. And to put this in perspective the curtain wall is 
>facing NNE and is 3 stories high.
>
>I would also truly appreciate any reference to a LEED CIR regarding
this 
>issue, if there is one.
>
>  
>

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