Ventilation issues

Hi everyone I’m new here, and fairly new to engineering, I’m working on a design for a product, with out giving to much away I’m trying to create a room with ventilation, so an exhaust fan will be drawing air out of the room, currently I have one inlet, but room becomes a bit of a vacuum, what I would like to do is have the exhaust drawing air out from the top of the room and a series of holes along the floor of the room drawing air in, how would I calculate how many holes and what size holes I would need to allow the fan to draw the correct amount of air with out causing a vacuum or putting unnecessary strain on the fan
Thanks in advance