My 1999 Coleman Cheyenne Camper has a 15000 BTU air conditioner on the roof. I can cool my entire 400 square foot living room with a 5000 BTU window air conditioner that uses a lot less power. Aside from the fact that a pop up canvas is porous and therefore may require more cooling, why do pop up campers need such large AC units?. I have seen some hardside campers such as a Scamp or the little snoozy that have traditional window AC units built into them that run on only 15 amps. I see the advantage of this is that you can run them off a much smaller and quieter generator. I have seen a few pop ups with people have put Macy's in them that are also 5000 BTU units. But I am still confused as to why 15000 BTUs is required?