Those HVAC units that are more than ten years old are not energy efficient hence have to be replaced with a new one. Consuming a lot of energy will not only make it expensive for you but is also not good for the environment. The government is now trying to make citizens understand the significance of using energy star rated appliances and EERE or Energy Efficiency and Renewable Energy. The energy star is rated by evaluating the appliance’s energy consumption rate. The energy star rating is developed by the Environmental Protection Agency and Department of Energy. The appliances that are energy star rated does not differ in functioning but uses lesser energy than the appliances that have no star rating. A Yellow star will be on the unit which indicates how much less energy the unit will use while functioning, the more the number of stars the lesser energy it will consume.
Also look for the SEER ratings, a higher number indicates higher energy efficiency. Now all HVAC units come with a minimum SEER rating of 13 it can go up to 17. Though a HVAC unit with a higher SEER rating will cost you more it will pay off in the long run from the savings that you will be able to make from the energy bills. Apart from HVAC units many other appliances like water heater, dishwasher, refrigerator etc. also come with energy stars and SEER ratings. The government is even providing subsidies for replacing old energy consuming HVAC units with new energy efficient HVAC units.