Old SHGC

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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

Erin Rowe's picture
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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
-Just curious, Did Oregon adopted Epro as it's own code compliant approved software? How do you get your baseline?

Nikola

Nikola Kravik's picture
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Joined: 2011-09-30
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