[Bldg-sim] SHGC adjustment and LEED impact q?

Anne Juran juran at summerconsultants.com
Thu Jul 14 05:24:35 PDT 2011

Yes, lots of framing results in a system SHGC lower than the COG SHGC.  I
know Kawneer does publish their data, although it is per AAMA 507, which is
a testing standard similar to NFRC 200, which is what 90.1 requires. See
page 34 of
A.pdf for an example.


I have submitted a LEED project using the manufacturer's info, but it is
currently under review, so I cannot give you a good answer.  I would hope
that as long as you have the manufacturer's published info per NFRC 200 you
would be okay.



From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Robby Oylear
Sent: Wednesday, July 13, 2011 12:36 PM
To: Nikola Kravik
Cc: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] SHGC adjustment and LEED impact q?


Hi Nikola,


In order to meet LEED EAp2 Minimum Energy Performance, the project must
comply with all mandatory provisions of ASHRAE 90.1-2007.  Section 5.4.2
Fenestration and Doors requires that fenestration performanc be determined
per section 5.8.2.  Section Solar Heat Gain Coefficient requires
that the SHGC for the overall fenestration area (including framing) be
determined in accordance with NFRC 200.  


If you read the exceptions, what you have done previously (use COG SHGC) is
an acceptable method per exception b.  The method described in your
quote below is not acceptable unless you are provided with an NFRC
simulation or certified product number showing that the SHGC is 0.25 when
framing is accounted for per NFRC 200.


Robby Oylear, LEEDRAP BD+C

Mechanical Project Engineer

Energy Analyst


RUSHING | D 206-788-4571 | C 206-354-2721

 <http://www.rushingco.com/> www.rushingco.com 


On Tue, Jul 12, 2011 at 1:06 PM, Nikola Kravik <nkravik at mazzetti.com> wrote:



Can the statement on the SHGC reduction below (0.29 down to 0.25) be true if
you have a lot of framing? 

I've always increased the U value to adjust for the frame effect, but never
decreased the SHGC~ 13%; I've actually left it same as the COG SHGC, now I'm
asked to plug this 0.25 instead of 0.29;

Can anyone share thoughts if this will fly with LEED v3 since I believe that
a 4'x6' window can't be slightly lower on SHGC but not 13%?


<http://www.viracon.com/downloads/resources/BDESSustainableFlyer.pdf> the
glazing selected (VNE1-63) has the highest light-to-solar-gain ratio of any
one available.  The SHGC at center-of-glass is 0.29, and scaled to account
for framing the unit SHGC is 0.25-exactly the ASHRAE reference value for our
climate zone 2A..referring to ASH 90.1-2007;




I appreciate your feedback.







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