well the one thing that i noticed about heat issues with lighting is that if u use a air cooled hood with out ventilation the room heats up much faster,because u have all that metal and glass retaining heat,but with the bat wing style,there is much less metal to trap the heat in,so doing a passive system with the biggest fan should be good.and its best to vent completly out side instead of into the next room because of the potential for doors being left open and that old grow box heat venting right back into the box.:thumbsup: