Re: [EnergyPlus_Support] Outputs

[Clarice Bleil de Souza <claricebleil@xxxxxxxxxxxx>]

Hi Mike,
   
  Loads of thanks for the reply! Everything is cristal clear to me now!
   
  Regards,
   
  Clarice

"Michael J. Witte" <mjwitte@xxxxxxxx> escreveu:
          > outside air I still would have the zone/sys sensible load to cooling setpoint
> reporting me the cooling coil sensible load only? I mean, does this variable
> report only the load when the coil is on?

No. The predicted load is the load required to meet setpoint after all non-
HVAC loads have been accounted for (which includes VENTILATION). If the HVAC 
system (in this case purhcased air) is providing the outside air, then the 
outside air becomes a load internal to the system and not a load in the zone. 

Draw a boundary at the HVAC system inlet to the zone:

Zone/Sys Sensible Load to Cooling Setpoint Predicted [W] is the rate of cooling 
that must enter the zone at this point to meet setpoint.

Zone/Sys Sensible Cooling Rate [W] is the rate of cooling the system actually 
provided to the zone.

If these values agree, then setpoint is met. If these values are different, 
then the zone temperature will be different from the setpoint.

Regarding the outside air option in purchased air. Do not use it. PURCHASED 
AIR is a variable volume device at a constant supply air temperature. It 
cannot and will not introduce unconditioned fresh air to the zone. If the zone 
load is small, the total volume delivered may fall below the outside air flow 
rate. This will reduce the outside air flow rate and a warning will be issued. 
For any situation other than peak loads where the total supply volume will be 
greater than the outside air volume, the outside air option in purchased air 
should not be used.

Mike

========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support 
EnergyPlus-Support@xxxxxxxx



         

 		
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