Are carbon filters effective enough to not require venting to the outside? I am planning a small grow op (39" x 117") with 900 Watts of lighting and up to 4 plants (legally). The room is a challenge to vent because its made of cinder blocks but there is a pair of existing 2" ducts to the outside (it was originally a basement root cellar). I can either 1) vent air out through the 2" duct to an area near the front door of my house, or 2) use that 2" duct as an inlet and vent through a wall to an adjacent utility room through a carbon filter (and ultimately to the rest of the house). I live in a cold climate and would like to be able to retain the heat generated by the grow lights somehow.
i'd vent into the house before I vented outside to my front door. Carbon filters work great, while the carbon is still activated. At least you'll get the heads up on your filter needing replacement before the rest of the neighborhood.