SEER stands for Seasonal Energy Efficiency Ratio, which is a rating system that measures the energy efficiency of an HVAC system. It is the ratio of the cooling output of an air conditioner or heat pump over a typical cooling season, divided by the energy it uses in Watt-Hours. The higher the SEER rating, the more energy-efficient the system is. A SEER rating is calculated by dividing the cooling output of the system during a typical cooling season by the power input. The SEER rating helps homeowners compare energy efficiency when choosing an air conditioning system. A good SEER rating varies depending on the homeowners individual preferences, but most homeowners opt for a unit with a SEER rating between 15 and 18, which provides a good balance between the upfront cost of the unit and the amount saved on utility bills. The SEER 2 standard will replace the SEER rating in 2023, which considers regional climate data and other factors to measure energy efficiency more accurately.