ok. If you have a air intake you should also have a vent for exiting air.
I place my intake (fresh air) as far away from the outtake (old air).
will you have intake and outtake? will they run at the same time? I like to have my outtake as high as possible and my intake also high on opposite sides. The idea is to extract the hot air (connected to a carbon filter). heat rises. Also the same with the intake. I try to schedule my intake of fresh air to turn on at the coldest time of day to help cool the room. this is usually from 3-5am.
hypothetically if you have really good air circulation it doesn't matter as much.
I have my carbon filter hung as close to the ceiling as possible in my hottest room. I have a carbon filter on the floor with duct up to the exit hole by the ceiling in my coolest room.