Ok so the new area ill be growing in is a closet. I can fit 6 plants in there, and Ill be using a 400w HPS. There is a door in the closet that goes under the house, and thats what ill be using for my ventilation. Im thinking about cutting 2 duct holes into the door, and then fitting mounts on them. and have the intake come from one side under the house, and the exhaust will be cleaned and then sent out at the other side under the building. My question is, during the winter, what will i do about the cold? I can't exactly have 40f air coming into my grow room. If anyone has any tips, tricks, or hints on ventilation Im all ears.