How is cooling capacity for room air conditioners measured? - Cooling capacity is measured by Btu or British thermal units. Room air conditioners with higher capacity in Btus have higher cooling capacity. One British thermal unit is roughly equivalent the thermal energy released by burning one kitchen match. That may not sound like much, but a typical home consumes about 100 million Btus per year. What is the EER for room air conditioners? - EER refers to Energy Efficiency Ratio The EER represents a room air conditioner s cooling output (in Btus) divided by its power consumption (in watts). The higher the EER is, the more efficient the air conditioner.