why does my house cool off so fast?
I purchased a home built in 1985. It is 1700 sq down, 1300 sq ft up with a cathedral living room and foyer ceiling. The basement is 1600 sq ft. A small area of the second floor is built out over the garage. I installed Schuco double-paned Corona 4000 windows (krypton in most, argon in the rest) and Precision doors (argon) throughout. I leave a few windows cracked on each floor to keep some air flow. Last summer when I had all windows and doors shut during a very hot week, we definitely suffered from stale air syndrome. So I assumed that the house was reasonably "tight". However, I still notice after the thermostat cycles to "away" that the house will lose 6 degrees (from 70 to 64) in about an hour. Is this good, average, or poor heat retention? What can I do to improve it? Right now I have no window treatments (building the budget), that is a variable open to manipulation. More attic insulation (I have the fluffy white stuff), more basement insulation? I have a 14 SEER heat pump upstairs, 14 SEER AC and 95% efficiency furnace downstairs (is there such as thing as 98% efficient? it is at least 95% efficient) and my average monthly electrical + gas utility is $160, which seems to me to be pretty good. I live in North Carolina. Thanks for your thoughts.