We install, replace, and service all brands of air conditioners, including roof top units for our commercial customers. Air conditioning units have an average useful life of 15 years. The older the unit, the more energy it takes to run it. The size of the unit is determined by the size of the air conditioning space in the house. The SEER (Seasonal Energy Efficiency Rating) per government standards is the amount of energy used to create the conditioned air in the home. In 2013, government regulations require a new unit to be a minimum of 13 SEER. Higher efficient SEER ratings are available and are recommended for anyone staying in a home for more than 5 years. You will see the savings in your energy bills.