HVAC-Heat Pump Discussion moved from here...
Have you had someone put gauges (or do you own them and already did it) and check the Freon level of the AC of your HVAC? My guess is, it's between 1-3 pounds low....I have another spreadsheet that I use to record HVAC run time, electricity usage, water heater run time, and water usage. I can tell you how much each of my showers cost accurate to within pennies.
Such information helps me identify areas where I may want to conserve or to detect problems. For example, my HVAC run time has experienced a very slight, but noticeable and steady increase over the last seven years that does not correspond with changes in average temperature. I suspect the efficiency of my HVAC system is decreasing over time, but lower electricity rates and more efficient devices have masked the increase in run time. The average person wouldn't notice because the net effect is that the electric bill has remained stable over time, but all the data that I collect and analyze gives me additional insight...