Most RV's are not insulated that well. The manufacturers know that the vast majority are going to be used on weekends or for short trips and when the weather is suitable for camping. Add in the popularity of slideouts; which require a large opening to be cut into the RV, and you have a ton of ways for heat or air conditioning to escape. The temperature of the floors on a cold morning are also an indicator of how well insulated your RV is (that cold air loves to occupy the open space between your RV and the ground). Those of you with heated floors don't count, and I am envious. You can also not count on any labeling that might describe your RV as having superior insulation built into it. Some manufacturers call it a Northern Package, for instance. You can look for certain things that will help in cold weather when you purchase an RV. Heated tanks and an insulated and sealed underbelly are a good place to start. Keeping the weekend and short trip usage in mind, most manufacturers put in a propane heater powerful enough to overpower the cold most campers will encounter. We like to call it the "big heater". If you have heat pumps they will handle most of the temperatures that the average camper encounters, negating the need for the propane heater. Because of the cost we have found that when we are fulltiming (living in the RV) an alternative to the propane furnace has to be found. It simply consumes way too much propane. We use space heaters and have been surprised how effective they can be. The only problem we have encountered is that they do pull a lot of amperage and you have to be creative about where you power them from. We are pleased with our 5ver, as we have been able to keep the inside at about 70 degrees, even on the coldest mornings. So, if you're not paying the electrical bill I suggest you use a space heater or two.