ᐅ Exhaust air and supply air above each other?

Hello,
we are just about to submit our building permit / planning permission application. I still have some concerns about the ventilation system.

My architect says that the exhaust air can be installed low and the supply air above it, with a 2m (6.5 ft) distance between them.
My worry is that the stale air, which is known to rise, might be drawn back in.

Are my concerns justified, or is this not an issue?

Alternatively, the exhaust air could run along the ceiling to the far end of the room. However, that would probably take up shelf space and is less compact.

Routing around the corner is not possible since the room is centrally located.

Thanks in advance for your opinions.

Best regards,
Christopher

Actually, it’s not that great... but we have it in the bedroom as well (and directly) – works better than expected.
Is that a central system?

Not inside the rooms. The exhaust and supply air that goes from the utility room/HAR to the outside.

Supply and exhaust air going from the utility room to the outside?! No ventilation system, except for a decentralized unit in the utility room? Or are you referring to the heating somehow?

A standard KBE system. Every house has exhaust and supply air near the utility room.

And why not side by side? That's how we have it. Outside, there aren’t any "intake towers," just two 90-degree bends with grilles, facing in opposite directions.