I have my first bill after installing three 1 ton 120V minis. I haven't been able to compare degree days yet but hope this could help those considering replacing their old heat pumps. I went back the two years available on my billing. My use of 1036 KW was 471 KW less than any other month and 31.3% less than the average of the 5 lowest months. I have a 3 BR 2 bath home of 1900 sq ft. It is 35 years old but was "certified" by the power company at that time. The only above and beyond was 6" walls.
I am watching the uniformity of temperature closely. So far with temps maxing at 90 degrees, the 3 units are keeping the whole house at 72 +/- one degree so far. I have a unit in the MBR/bath, den and kitchen. I am debating a 9K mini in the guest BR or just a small window AC unit.
The only other variable that would increase my usage is that the wife insists on 68 degrees in the MBR for sleeping. I crank down that unit about sundown every night.