I think it's working good for me. I've only been in the upper 20's (Florida's cold) in the bus. I used black out material on the curtains. I only get some condensation on the windows and non on the inside metal parts. I've only had to use a space heater to maintain 70 inside the bed room. I also have a Rv propane furnace if I need more heat. I use a curtain between the bed room and the kitchen that also has blackout material on the bed room side. This keeps the cold in the front.