Hey great to be back. Haven't grown since 2014. Have since moved and want to start again. I just built a 18x30 ft steel garage non insulated in my backyard and would like to section off a enclosed grow area mabe 6-7 ft wide 7ft long and mabe 8-9 ft tall. If temps outside are 10-30 degrees what do you think temps will be in my grow room if I fully insulate it and have 2 400w hps lights in cool tubes. Can you help me out on what I need to do to control temps.. I imagine they will be fine when lights are on but when timer kicks lights off it will be 2 cold. Could I place a space heater inside room to kick on when lights go off?? Any help would be appricated thanks.