There are two basic paths here in EnergyPlus:
- Use the simple ZoneVentilation objects to apply ventilation to your zone when it's hot (by far the simplest option)
- Use the AirflowNetwork to try to better account for interzonal airflow etc.
As Denis notes, there are a lot of uncertainties in ventilation modelling regardless of what you do, and to be honest one of the first things you'll need to accept is that whatever you do your modelled ventilation will be "wrong", whether due to the inaccuracies in the calculations or the uncertainty in occupant behaviour. The only thing you can do is try to manage this with sensitivity analysis, and factor this into your analysis.
Both of these work on the setpoint system, and will apply ventilation/open the windows when the temperature rises above your setpoint. I'm not sure why you're finding that the windows are only opening in winter - possibly if you're running the humidity control EMS example then with your weather file it's only hitting the humidity setpoints in winter?
Anyway, if you are wanting to use the AirflowNetwork then looking at the use of the EMS is advisable, because the AFN's basic window controls are terrible.
In brief, the window opening control logic of the AFN is deeply flawed and is prone to both overcooling and runaway overheating. This is because EnergyPlus has no good way of determining how much ventilation is needed, and how much the windows should be opened, other than toggling them open and closed each timestep. Rooms with significant ventilation potential – such as spaces with sliding doors and cross-ventilation – can readily achieve very high air changes (e.g. >70ACH) in windy conditions. If this happens when the air outside is relatively cold, this can cause the zone temperature to plummet rapidly and fall below the heating setpoint (more likely to occur when the setpoint is relatively high such as 20°C). At which point, the heating is turned on, the temperature rises again, and as the conditions that caused the overheating in the first place still exist the ventilation setpoint is reached and the windows open again, causing the model to bounce between heating and ventilating. EnergyPlus attempts to control window opening by allowing opening area to scale based off the difference between indoor and outdoor temperature, reducing window opening area when the outdoor temperature is significantly lower than the indoor.
The main tool EnergyPlus uses to try to scale window openings is the window opening factor. The stated intent of this parameter is to try to prevent excessive temperature swings by reducing the window opening area if the difference between the indoor and outdoor temperatures is large. The problem is that ΔTin-out doesn’t actually make any sense as a window control parameter, and this becomes obvious when you think about it and realise that you can increase ΔT by increasing the indoor temperature. In other words, the worse it’s overheating, the less E ... (more)
