very little vent needed ,all you need to be sure of that you have air flow running through your room 24/7.on a small set-up computer fans can do the trick. when lights are on leave door slightly ajar and use any household fan to serculate air.what i will try to do in the next couple of days is take pics of my grow room to see if that helps in any way.sorry cant do at moment something wrong with my digital camera.