If you only have 1 tent in the room and are using a cooltube and 440 cfm fan you shouldn't need cool air from outside. Also a 1000 watt bulb and ballast puts out almost as much heat as a 1000 heater. Venting it in another room will cut your heating cost a little and add humidity of it is too dry. Not sure if you are in a legal state,but, one thing cops look for is ice build up around exhaust vents,a tell tale sign of a grow room.