just make sure you are sucking hot air out instead of pshing cold air in. This means you should keep your fan for exhaust as high as posible to suck out the heat that rises. if your room is air tight or very close to it you can use both fans for exhaust and just have ventilation tubes going from inside to outside. sucking the air out will make a vaccum in your room automatically sucking air in from outside. my exhaust system only uses one fan for exaust of my room and one for exhaust of my lights. hope this will help...