SEER, or Seasonal Energy Efficiency Ratio, gauge the efficiency of an air conditioner. Less power is used when the number is higher. The actual SEER of an HVAC system may be impacted by choosing the right amount of cooling and correctly installing the system. SEER is similar to how we utilize a car's stated fuel efficiency. 30 mph is feasible under some circumstances, but not, for instance, if you're sitting slowly along IH-10 during rush hour.