Airflow-network interzone surface

I am simulating natural ventilation in a house through an airflow-network in energyplus.

Interzone surfaces are defined twice in the building surfaces. I have looked at the example files and they only define those surfaces once for the Airflow-network Multizone:surface.

Should those be defined twice in the the airflow network or only once?

What is advised? does it affect the results depending on which side of the wall is included in the network?

Hello Jevin,

You should define interzone surfaces only once inside the AFN.

Quote E+ input-output reference:

It is possible to define an interzone surface twice in EnergyPlus, once in each of the zones that the surface separates. Previously this was a requirement of EnergyPlus (prior to version 2.0), but now it is optional and the user also has the option of only defining the surface once (EnergyPlus defines the second surface automatically within the program). For each interzone surface, use only one (of possible two) interzone surface names in the AirflowNetwork:Multizone:Surface object for “Surface Name.” Do not enter two AirflowNetwork:Multizone:Surface objects corresponding to the two possible interzone names. This would cause the air flow through the surface to be counted twice