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Re: [EnergyPlus_Support] Solar Angles Calculations



Thanks Brent.
It matches perfectly.

If the user doesn't change the default values from 20 to say 1, then E+ will use the average values Or E+ internally calculates the solar angles based on time steps.

regards,
Saleh

From: "Griffith, Brent" <brent.griffith@xxxxxxxx>
To: "EnergyPlus_Support@xxxxxxxxxxxxxxx" <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Wednesday, October 24, 2012 9:51 AM
Subject: RE: [EnergyPlus_Support] Solar Angles Calculations

 
In the ShadowCalculations object, you can control the frequency of the solar angle calculations.  For something like this you will want to set it to 1 day.  The default is 20 days, so the solar angles are an average for a 20 day period of time.
 
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of saleh saadi
Sent: Tuesday, October 23, 2012 7:18 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Solar Angles Calculations
 
 
Hello Everyone,
 
I'm trying to understand how E+ calculates the solar angles such as incident angles on tilted surfaces (or simply for vertical surface). I have used correlations in Duffie and Beckman Book " Solar engineering of thermal process" to calculate the solar angles. I extracted data of cos of incident angles from E+ (output: Surface Ext Solar Beam Cosine Of Incidence Angle) and compare the two results. For some days, the values are matching but for others they are off . For this exercise, I have used a vertical south wall with no shading, and no windows. 
 
For 1hr time step:
Does E+ calculates the solar angles at the end of the time step or at mid point of time step? or averaged over some points in a time step?
 
thanks,
Saleh




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