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RE: [EnergyPlus_Support] SHGC and solar transmittance

Yes, EnergyPlus will calculate things differently for the two windows.  

 

Keep in mind that SHGC is defined under a set of standard conditions.
Two different windows could line up to have the same SHGC under the
standard conditions, but won't necessarily perform the equally at all
times during annual simulation.  

 

In general, there will be more time lag associated with the radiated
portion of solar heat load because it will first arrive at inside
surfaces of the zone.  The portion of heat that is convecting off the
inside face of window will go straight into the zone air and show up as
load right away.  

 

You would have to run both windows to see which has the higher peak.  My
guess is the 1st case would have higher peak, but it really depends on
the particulars of the zone in question

 

 

________________________________

From: EnergyPlus_Support@xxxxxxxxxxxxxxx
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of
lorenzomattarolo
Sent: Thursday, July 05, 2007 3:58 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] SHGC and solar transmittance

 

Hi,
I'm simulating a zone with a glass facade.
I want to have 0.15 for the SHGC of the window:

I run two simulation

1st case: window with SHGC=0,15
solarTransmittanceNormIncidence=0,06

2nd case: window with SHGC=0,15
solarTransmittanceNormIncidence=0,10

Basically the amount of solar heat entering in the zone is the same
(since the SHGC is the same), but the amount of solar radiation
(beam+diffuse) is different.
Does Energy Plus make any difference for calculating the cooling rate?
In order to estimate the cooling peak value, which case should i
consider?

Many thanks,

Lorenzo

 



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