So I would love some feedback. I have been using the equation below for Natural Gas in CCF:

Cost(heating) = (Heating Degree Days) X Energy Cost ($/CCF) X (1.08 BTU/Hr-CFM-F) X (24 Hr/Day) X (1/Equip. Efficiency) X (1 CCF/103,700 BTUs)

The cost to heat 1 CFM per year. Take that along with the CFM of heating you saved over the year and you get your annual savings.

Is there another or multiple other was to calculate this? Thanks!
Frank