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Hello! I am trying to understand the EnergyPlus heating and cooling energy outputs. I simulated a simple building, first with ZoneInfiltrationDesignFlowRate and ZoneVentilationDesignFlowRate and then entering these rates through the OutdoorAir option. In both cases the HVAC system used was an Ideal Loads Air System. What i don't really understand is the difference in the energy outputs. In the first case, the Zone Air System Sensible Heating/Cooling Energy values were equal to the Zone Ideal Loads Supply Air Sensible Heating/Cooling Energy ones, except for the first hour of the system's operation every day. However, i expected the same results from the Zone Ideal Loads Supply Air Sensible Heating/Cooling Energy output on the second case, but the actual results were about 20% higher. From other posts i excluded the Zone Air System Sensible Heating/Cooling Energy results, which were much lower than the relevant in the first case. Could someone explain to me why this difference exists and which is the proper output variable i should use for taking the proper building energy needs? Thank you in advance!

Hello! I am trying to understand the EnergyPlus heating and cooling energy outputs. I simulated a simple building, first with ZoneInfiltrationDesignFlowRate and ZoneVentilationDesignFlowRate and then entering these rates through the OutdoorAir option. In both cases the HVAC system used was an Ideal Loads Air System. What i don't really understand is the difference in the energy outputs. In the first case, the Zone Air System Sensible Heating/Cooling Energy values were equal to the Zone Ideal Loads Supply Air Sensible Heating/Cooling Energy ones, except for the first hour of the system's operation every day. However, i expected the same results from the Zone Ideal Loads Supply Air Sensible Heating/Cooling Energy output on the second case, but the actual results were about 20% higher. From other posts i excluded the Zone Air System Sensible Heating/Cooling Energy results, which were much lower than the relevant in the first case. Could someone explain to me why this difference exists and which is the proper output variable i should use for taking the proper building energy needs? Thank you in advance!