The Seasonal Energy Efficiency Ratio (SEER) measures the efficiency of cooling systems, such as air conditioners and heat pumps, over an entire cooling season. It is calculated by dividing the total cooling output (in British Thermal Units, or BTUs) by the total energy consumed (in watt-hours) during that period. A higher SEER rating indicates a more energy-efficient system, which can lead to lower electricity bills and reduced environmental impact. SEER ratings are important for consumers when selecting HVAC systems, as they help compare different models. The U.S. Department of Energy sets minimum SEER standards to promote energy efficiency. Homeowners can benefit from understanding SEER ratings when making decisions about their HVAC systems.