I vent mine into the bathroom right next to my closet. Normally that bathroom is cold as fuck in the winter so its a win win. in the summer it will be going threw the ceiling vent thats in the bathroom
I vent mine through a window outsode of my grow room. In a past grow op i vented to the adjacent room. Really depends on your grow room location, heat/ light situation ect..
One easy and cheap method is to get a 20-inch box fan ($20 at WalMart) and put it in the doorway, on the ground, of your grow room. I flipped the fan around so it sucked into the room. My thinking was that the forced cooler air coming in would force the higher warmer air out the top of the doorway. Make sense?