How much energy does an air conditioner with an 9.7 EER save as opposed to a 10.7 EER?
A 10.7 EER units uses
E.E.R. equaled the rated cooling output of an HVAC unit in BTU's per hour divided by the rated input of energy in watts of electricity, at specific humidity, and temperature input/output conditions.
AT the nominal rating conditions this is similar to the car fuel "mpg" rating. Thus, the percentage difference can be directly compared. The cost difference will vary with actual climatic conditions and power costs.
Actually, the higher value is the one that uses less energy!