Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
The 'Zone Air ###' outputs are the average value for a zone and the 'AFN Node ###' outputs are generated for each node in the airflow network that you define with an AirflowNetwork:Distribution:Node object. Taking the CO2 Concentration example that you referenced, here is the documentation for 'Zone Air' and here is the documentation for 'AFN Node'.
The key value for the 'AFN Node' outputs should be the names of the AirflowNetwork:Distribution:Node objects in your model. One might match the name of each zone for the zone air node, but you will also have nodes after coils, fans, and other HVAC components in the airflow network. I don't think there are AFN nodes associated with surface names. If you set the key value to an asterisk "*" then EnergyPlus will generate all possible outputs for the variable you request.
