If you’ve shopped around for A/C units, you may have come across a score for the A/C unit. That score is known as its SEER rating. Standing for Seasonal Energy Efficiency Ratio (SEER), the SEER rating measures the energy efficiency of the A/C unit. In general, the higher the SEER rating of an A/C unit, the more energy efficient that unit is. The highest score, 21, is an A/C unit that practically pays for itself, and while it may be great to have a unit that efficient, they are usually quite costly. We typically advise that customers install a unit that has a score of at least 14 as the U.S. Department of Energy considers that the minimum for a unit to be an energy-efficient classification.