How do I create a simulation that has natural ventilation of a building, with a window? The outside air goes into the building through the window.
Then for the second simulation, there is a panel blocking the window from the outside air from going into the building.
Hello,
I posted a project some time ago in forums, where I evaluate a similar scenario. I’m using chimneys instead of windows, but the logic is the same.
Basically, if you have a “hole” on the wall, representing the window, then the air can go through it.
If the window is closed, then you simply close the hole in your CAD model.
Hopefully that makes sense 
