I'm in the Detroit area...
I have compiled by gas usage from 9/1/04 to 2/3/06 by billing dates, as
well as heating degree days for those same range of dates.
Since I have been refinishing my basement, AND turned the thermostat
down from 70-71 to 67, I would like to anaylze how much more efficient
my house is. The basement is no longer pouring cold air into the
upstairs since I have insulated and drywalled the outside walls.
So how do I compare these with different heating degree days? If the
heating degree days is 10% less this year from last, would you expect
10% less gas usage? Or is it not linear?
For a great example:
1/6/05-2/5/05 -- 30 days, 43.9 heating degrees PER day, 12.433 ccf/day
1/6/06-2/3/05 -- 28 days, 30.54 heating degrees PER day, 8.1 ccf/day
I should also note that I would estimate approx 0.65 ccf/day for non
furnace related gas usage (that's how much was used during july/august
when the heater was off completely).
Is this a good savings? It looks pretty good to me!