FIY: In the state of Ohio, where electricity costs $0.157 / kWh, it would cost $1,119 to run your 14 SEER central AC for a whole year. A more efficient 18 SEER central AC would cost $906 per year.

The saving from upgrading to a higher efficiency system would be $212 per year, and it will take just 7.2 years to recoup the extra upfron cost.