Exhaust air and supply air one above the other?

We don’t have any "towers" in the garden, but rather the KBE system in the utility room. According to the architect, the supply air would then come in above the system and the exhaust air would go outside through the wall below the system.

Side by side is also possible, meaning the exhaust air goes out on one side of the room and the supply air comes in on the same wall but on the other side. It just takes up space in the room. That’s why the question is, is it also possible one above the other or is there a risk that the bad air coming out at the bottom is sucked back in at the top?

That’s why the question, is it also possible to have them above each other or is there a risk that the bad air coming out below gets sucked back in at the top?

Supply and exhaust air vents should be at least 2 meters apart and the supply air openings also 2 meters above the ground (because of radon). Then you should also consider the main wind direction to avoid a short-circuit effect in light wind.

We don't have any "towers" in the garden, but the KBE system in the utility room.

What is a "KBE" system? The supply air then comes centrally through a long duct system into the ventilation unit in your utility room? Usually, the exhaust air is warmer than the supply air, i.e. the warm air rises upwards and it could indeed be that you then suck in the exhaust air again with the supply air if you place them one above the other...

What is a "KBE" system?

I wonder that too ... : As a general rule, I would advise against the planned arrangement "one on top of the other." A floor plan could help to understand this better. I don’t yet understand the problem why what works perfectly fine in thousands(?) of other single-family houses shouldn’t work for you.

What is a "KBE" system? Does the supply air then come centrally into your utility room in the ventilation system via a long duct system?

KBE is shown on the plan of the system. It is a normal ventilation system that is screwed to the wall in the utility room and exchanges the air in the rooms.

Usually, the exhaust air is warmer than the supply air, i.e. the warm air rises ...

I know that and it is also stated in my first post. Hence the concerns.

Controlled Ventilation and Exhaust maybe?