How to make an opening in a room that is completely open?

Hi,
I am simulating a 15 floor residential building for energy consumption. I have to make an opening that is completely open(not a window). like i have made the room as a zone. And i have attached a surface on one face of that room to act as the opening.
Please help me with this. How to make this opening/ input the detail of this opening for simulation?

You can set it to be an AirBoundary.

I have to make this opening on outer wall. So its not a surface between 2 zones. I dont know how to input this in model?