Compare the zone temperature with the zone inlet node temperature (not the set point temperature). Also look at the zone inlet node mass flow rate. You could also add the zone and zone inlet enthalpies and calculate that value yourself to compare. Q = Mdot * delta H
The Zone/Sys Sensible * Rate also includes information other than what energy is entering the zone through the zone inlet node (the IO Ref does not say that or tell you what else is included) so if your calculation and the reported sensible rate are different, you would need to see what other data is included in that report variable..
HVAC timestep can at times be shorter than the zone timestep. It would be good to check the output on detailed frequency.
Output:Variable,*,Zone/Sys Sensible Heating Rate, Detailed;
Output:Variable,*,Zone/Sys Sensible Cooling Rate, Detailed;
Also you might want to look at the Predictor-Corrector procedure of energyplus. It is documented in Engineering reference. This small energy consumption could be because of this prediction procedure. It predicts the possible future load and make some heating/cooling so that setpoint is achieved at the desired time.
You should see this behaviour by adding these variables:
Output:Variable,*,Zone/Sys Sensible Load to Cooling Setpoint Predicted,Detailed; !- HVAC Average [W]
Output:Variable,*,Zone/Sys Sensible Load to Heating Setpoint Predicted,Detailed; !- HVAC Average [W]
Vaibhav Jain
On 27 June 2012 18:25, David Frostclapp <drf10@xxxxxxxxxxx> wrote:
When looking at the timestep output from my program I noticed the report variable Zone/Sys Sensible Cooling energy reporting non-zero values despite the temperature of the zone being well below the cooling setpoint at all timesteps. I began testing the HVAC template example files and noticed the same occurrence despite eliminating the cooling system and outdoor air.
I was hoping someone could explain why the output variable Zone/Sys Sensible Cooling Energy reports cooling values (albeit quite small); however, cooling is completely turned off and there is no outdoor air going to the zone, in addition, I shrunk infiltration to a tiny value.
All wisdom appreciated!
David
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