do u have a co2 controller? and a co2 monitor? if not get 1 then set ur co2 under 1 of ur oscillating fans..and the co2 monitor in the middle of the room....i have this 1 Sentinel CPPM-4 CO2 Controller
you will need a exhaust fan and a intake fan with the same cfm. if u work in ur room u will need to turn it on so u dont pass out as u breath the ppm's will go up and go up fast...i have the same room 15x40x10...3.5 tun excel