I'm looking to grow in a few months. I have a 2'x2'x7' wardrobe. I plan on using a 250w hps because a friend of mine is giving it to me. I don't think heat will be a problem. I plan on cool tubing it. I am worried about it getting too cold however. It gets really cold here in the winter. I leave my window open all winter as well. This will be great for getting rid of heat but bad for periods when the light is off. How do I combat the cold. I'm also looking for ventilation recommendations. I don't want to spend a lot of money in that area. Thanks for your help ahead of time. 
