[Bldg-sim] Old SHGC

Nikola Kravik nkravik at rumseyengineers.com
Tue Oct 20 20:58:37 PDT 2009


Erin,

Depends on your building size, system type/size, orientation, shading, outdoor  conditions, etc....Are you looking at overall $cost or therms or kWh saved.  Is it 30 WWR out of 50k sf or 200k sf bld?
U value will impact heating and cooling and other things in lesser value, but if it's heating only/no cooling-will be more drastic difference.

You can check Epro support to see how the SHGC is calculated in the software: support at energysoft.com<mailto:support at energysoft.com>
-Just curious, Did Oregon  adopted Epro as it's own code compliant approved software? How do you get your baseline?

Nikola

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Erin Rowe
Sent: Tuesday, October 20, 2009 5:16 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Old SHGC


Hi All,

I've been looking through a model in EnergyPro that has a SHGCc of 0.99 entered into the baseline model, because the existing office baseline building is old single-pane 1/8" glazing (window:wall ratio is about 30%). However, a more reasonable assumption here, based on the non-residential Oregon code compliance manual would be SHGCc =0.86.  The issue I'm having is that I can't re-run the model so I have no way of telling how this might impact energy use.  My hunch is that this difference in SHGC would have mimimal affect on the energy consumption.  Any thoughts?

I've also been told that while the EnergyPro input for glazing characteristics is SHGC, EnergyPro actually treats this input as a Shading Coefficient in the calculations.  So, if this is the case then an input of 0.99 shading coefficient would actually calculate to be a SHGC of 0.86, and would be the correct input. Does anyone know if this is true?


I'd appreciate any feedback you have.

Thanks,

Erin



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