Ventilation ACH through interior opening

Hi everyone,
I used Airflow Network to simulate interzone ventilation. I built a simple case based on the AFN example file, in which there are three adjacent zone. Two of them are connected by interior door and window. Using this model I can have ventilation ACH from all three zones.

Then I removed exterior window of one zone to see if I can simulate single sided ventilation through interior opening. This time, I only have ventilation ACH values from zones with exterior window. Zone without exterior window (only interior window) have zero ventilation ACH all the time.

Is there anything wrong with the model or that is how AFN works (i.e. each zone must have exterior window)?

Thank you
Laksana


afn_apartment_model_mod.gh (108.2 KB)

Anyone can help me with this problem?
Thank you