insulation for sure,,, do not use the cool tubes in winter,,
you have to trail run a few days without plants, using meters and sensors to get a feeel for how temps run with lights on and off
I use a variac thermostate and a baseboard heater,, it only kicks on if temps get to low,, so during lights on the heater may stay off,, but if some heat is needed it will kick on,,, during lights off the heater is always on to some degree,,,
IF your humidity is in range,, you can recycle the air, my buddy made a cheapo box out of cardboard and feeds his exhaust into the box, and his intake is on the other side of thebox, then he just spreads the two hoses together or apart as needed to adjust the temp inside the grow space,, simple but really effective