- can we change the Ventilation Control Mode to other types like “Temperature” or “Enthalpy”? I didn’t find a component to do this
Right now you can only control ventilation with Temperature. The “Temperature” Ventilation Control Mode is actually much simpler then what HB exposes. It just opens windows when T_{zone} > T_{out} \text{ and } T_{zone} > T_{set}, which are all inputs that are exposed in the HB Ventilation Control component.
- the Ventcontrol component will effect the following code, and change the open factor of the openings. But like the E+ reference says: " NoVent : All of the zone’s openable windows and doors are closed at all times independent of indoor or outdoor conditions. The Venting Availability Schedule is ignored in this case. This is the default value for this field." So what is the meaning of the Ventcontrol then?
The ventilating action can be controlled at the zone level or surface level. Ventilation at the zone level means all zone windows are synchronized to a single control strategy, whereas the surface level permits individual windows or doors to have different control strategies. You’re looking at the AFN’s Zone object, so the “NoVent” there just means ventilation isn’t controlled at the zone level, finding the AFN Surface, and SimpleOpening objects will indicate the actual control strategies applied in HB.
But I still can not make sure the difference between “Group – Airflow Network” and “Group – Airflow”
The basic difference is that the Airflow Network group numerically simulates the evolution of air pressure in the building per timestep, which drives the airflow, whereas the Airflow group uses simple equations that simulate airflow based on some estimate or approximations of air pressure difference.
So the AFN will simulates infiltration using dynamicly changing pressure:
Q_{infil} = C \sqrt{P} \text{ } [m^3/m^2 s]
Whereas the Airflow group will just assume a constant Q_{infil}=0.00056 \text{ } m^3/m^2 s, based on benchmarks from blower door tests which correlate infiltration rates with envelope pressure difference for target airtightness.
The documentation has a section on what the AFN is meant to be used for: Group – Airflow Network: Input Output Reference — EnergyPlus 9.3