Now days when you have a HVAC sales person or technician to your home and you are trying to decide on which model to purchase, you will find that air conditioners and heat pumps have a rating for efficiency called a SEER rating. What are they talking about? The axiom SEER stands for "Seasonal Energy Efficiency Ratio". Efficiency is of course one of your most important considerations. An efficient system will not only lower your energy costs, it will also lower your impact on the environment.