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RE: [EnergyPlus_Support] relation between "Air balance air energy storage" and air temperature variation

I suspect you need to report at the "Detailed" frequency and pay attention to variations in the amount of time that elapses between timesteps.  Longer reporting intervals produce averaged results.  EnergyPlus will shorten the system timestep when temperatures change quickly (so the dt value is not constant).

No, your equation is not quite right.  The variable is = Cv dT/dt.  But differences between "sum(thermal flux)" and "Cv dT/dt " can exist and are also be reported as "Zone Air Balance Deviation Rate" which is an advanced report variable.  These deviations are usually a result of non-smooth changes in internal gains.


________________________________
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of le_carambar [le_carambar@xxxxxxxx]
Sent: Monday, November 30, 2009 5:56 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] relation between "Air balance air energy storage" and air temperature variation



Hi,

Due to the definition of "air balance air energy storage rate", it should be a direct link between this output and the variation of mean air temperature of a zone.

Cv dT/dt = sum(thermal flux) = air balance air energy storage rate (W)

No ?

In practise, it works around 50% of the time.

"air balance air energy storage rate (W)" / ( Temp(step)-Temp(step-1) )
is often a constant (131 in my case) but not always.

Sometimes it's between 200 and 250, and I really don't understand which factors could entail this...

There is mostly something I misundestood...

Somebody have an idea ?

Thanks a lot





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