Natural Ventilation: When was the window opened and what was the air flow rate?

grasshopper honeybee-legacy
3

I know that I am several months late but here are the answers:

  1. Is there an output variable that directly describes when the windows are opened or what the airflow rate at the window openings is?

You can find a list of all request-able outputs by using the “HB Read Result Dictionary” component. Once you request them from a simulation, you can load the results using the “HB Read Custom Result” component. It looks like the following outputs might be of help:

Zone Ventilation Current Density Volume Flow Rate
Zone Ventilation Standard Density Volume Flow Rate
Zone Ventilation Current Density Volume
Zone Ventilation Standard Density Volume
Zone Ventilation Mass
Zone Ventilation Mass Flow Rate
Zone Ventilation Air Change Rate
Zone Ventilation Air Inlet Temperature
  1. Does E+ take into account that the window cannot open when the space is unoccupied?

This isn’t the default behavior bit you can specify a schedule that will get applied on top of any of the other setpoint controls. This schedule can be used to account for occupancy.

  1. How come E+ didn’t “wait” for the temperature to actually exceed 26C before opening the window? Is it the case that the results show the states at the beginning of each time step, so by the end of the time step the temperature was predicted to exceed 26C, thereby triggering a window opening which immediately decreased the temperature? In the definition, I actually set the simulation time step to 1h.

This question might be better for unmenthours.com. I don’t know exactly how E+ does the calculation for this case but I am pretty sure that there’s a pre-calculation before the actual execution of the behavior at the timestep. I at least know that the E+ “HVAC timestep” is different from the timestep of everything else. So I think the pre-calculation is probably happening during this “HVAC timestep”.

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