Improve the Energy Efficiency ...

Energy Class - Energy class is classification of the Air Conditioners according to their energy saving efficiency.
There are 7 different classes of efficiency, from A (highest) to G (lowest). Energy saving efficiency is a ratio between power input and cooling/heating capacity

EER ratio between power input and COOLING capacity

COP ratio between power input and HEATING capacity

Higher EER / COP means you are getting more
cooling / heating energy for 1kW/h of power input