Yeah what I do is just keep a window constantly open and have fans blowing in the closet into the grow. The fans pull the fresh air into the closet. My op with a 250w hps and my veg box with 250 w worth of cfl's increased the power bill by $30-40. you can balance it out by exchanging all the incandescent light bulbs in your house with cfl's and turning you computer off when not is use, and any other energy-saving ideas you might have. I don't feel ecologically guilty about using more power since the power plants here don't emit greenhouse gases. Hydroelectric and windmills mostly.