RawAlex, if you think a heat pump is efficient, you must not get below 28F very often.
When we were in Maryland and our heat pump died, and before we knew we were moving to Florida, I investigated a ground source heat pump. Basically, you have no external unit. They drill 3 holes about 120' deep into the ground and the ground becomes your coil & evaporator. Since the ground stays around 65 degrees, its very efficient in the summertime, and in the winter, since we had no real permafrost, it was very efficient. This was a closed loop system. There are other systems where you throw the loop into lakes or open loop systems that bring in groundwater. While operating, they are silent since the pump just pushes its refrigerant through the ground.
Like Cleo said, in Florida, I think we had our heat on for about two weeks this year. And no, very few heat pumps in Florida. Resistive heat -- you heat pump people might call that your Emergency Backup heat. The electric meter really spins when we heat our house.
