If you’re considering installing a new air conditioning unit, you may have noticed that there are various rating acronyms used: EER (Energy Efficiency Ratio) – is a measurement of the cooling output of an air conditioner divided by its energy usage, calculated under specific test conditions that represent peak load. A higher number means a more energy-efficient system. SEER (Seasonal Energy Efficiency Ratio) – measures the efficiency of cooling equipment, calculated based on a seasonal average instead of at specific laboratory conditions. A higher SEER rating means the unit is more energy efficient. HSPF (Heating Seasonal Performance Factor) – measures the efficiency of the system’s heat pump. A higher number means a more efficient unit.