Efficiency of a room air conditioner is normally measured as Energy Efficiency Ratio
(EER), which is the ratio of the cooling output, measured in British thermal units (Btu) per hour, to the power input (in Watts, and includes all inputs to compressor, fan motors and controls) to operate AC at standard rating conditions. This means a higher the EER, the more efficient the air conditioner is.
ENERGY EFFICIENCY RATIO FOR 2012-13 WITH STAR RATING
1 STAR - Minimum EER : 2.50 , Maximum EER:2.69
2 STAR - Minimum EER : 2.70 , Maximum EER:2.89
3 STAR - Minimum EER : 2.90 , Maximum EER:3.09
4 STAR - Minimum EER : 3.10 , Maximum EER:3.29
5 STAR - Minimum EER : 3.30
ENERGY EFFICIENCY RATIO FOR 2014-15 WITH STAR RATING
1 STAR - Minimum EER : 2.70 , Maximum EER:2.89
2 STAR - Minimum EER : 2.90 , Maximum EER:3.09
3 STAR - Minimum EER : 3.10 , Maximum EER:3.29
4 STAR - Minimum EER : 3.30 , Maximum EER:3.49
5 STAR - Minimum EER : 3.50