an inline fan to make sure the air gets there. to warm things up, i have ducting from my clothes dryer going into the basement, want to get another inline or maybe a blower to just pop onto it when i dont want to run the dryer just to heat. the house stays plenty warm to be effective to warm it up down there. when i'm flowering late, i'll cool the girls down to 55 at night. the mtf will get frosted during winter down to 35 for a night or two if i can help it. call it tradition but they respond to it very well, nice blue hues and highlights.
summers a different story, usually just run my blower on high into the basement through the damp/louv. and it keeps things pretty damn nice. again usually 70-75.. but then again, i'm only doing a little bit of growing inside during the summer if its a good sunny year, more or less just cloning and maintaining mothers inside.