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

[Robby Oylear]

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 5.8.2.5 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 5.8.2.5 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, **LEED®AP BD+C***

*Mechanical Project Engineer*

*Energy Analyst*



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

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

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

> Hi,****
>
> ** **
>
> 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%?****
>
> ** **
>
> …….that the glazing selected (VNE1-63) has the highest light-to-solar-gain
> ratio of any one available<http://www.viracon.com/downloads/resources/BDESSustainableFlyer.pdf>
> .  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.****
>
> ** **
>
> Cheers,****
>
> n****
>
> ** **
>
> ** **
>
> ** **
>
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