The less demand you put on a system, the less energy you’ll utilize and the longer your unit will last. There are several ways to do this:

• Avoid overcooling. Unfortunately, many buildings are far chillier than necessary. For most people, 78°F. degrees is perfectly comfortable. Yet many homes and businesses crank the temperature down as far as 65°. You can save a lot of money–and fight global warming–by the simple act of setting your temperature higher. Going upward a single degree, in fact, can reduce your air conditioning bill by 3% to 5%. If you are not going to be home, raise the temperature to 85° or 90°. You can use a timer to automatically bring the temperature down to 78° just before you come back.
  
•  Insulate and tighten up your house. No matter how efficient an air conditioning system is, it can’t perform well in a house with insufficient insulation and poor sealing. Checking for leaky ducts is particularly important. A huge amount of energy–well over $100 a year–can be wasted if they leak. Speaking of leakage, keep doors and windows closed when your air conditioner is on.
  
• Cool with fans. By circulating air, fans make us feel cooler, yet they use only a fraction of the energy required by air conditioners. Unless it is very humid where you live, a large fan that vents to the outside in the top-floor ceiling may radically reduce your need for air conditioning. Even a good attic fan can cut air conditioning costs up to 30%. Using your bathroom fan can cut your home’s humidity–another way to make you feel cooler.
  
•  Don’t cool unoccupied rooms. If you have room air conditioners, shut them off and shut the doors. With central air conditioning, shut off registers in some of the rooms you are not using. But, be careful. If the thermostat is in the room you have closed off, the system will continue running long after the rest of the home is cool.
  
•  Keep your AC clean. If you have a room air conditioner, remove and rinse off its filter (usually behind the inlet grill) every month. If you have a central air conditioner, have the condenser unit professionally cleaned at least every other year. Clean all registers and air inlets and outlets. This is important not only for efficiency, but to prevent buildup of dust and mold than can harm your respiratory system. Every three years, have a technician add a tune-up and inspection to the cleaning. Among other tasks, the technician will check your refrigerant level. If it’s low, you’re wasting as much as 20% of your air conditioner’s energy. Proper airflow is also critical.
  
•  Buy energy-efficient appliances. All electrical devices give off heat, so consider replacing old refrigerators and incandescent light bulbs. Unplug electronic equipment when it’s not in use.
  
• When you paint or re-roof, consider “cool” exterior finishes. Light-colored or other “cool” roofing and siding products can reduce peak cooling demand by 10% to 15%.
  
• Be aware of windows. Close drapes and shutters on windows on the sunny side of the house. If it’s time to replace your windows, get the double-glazed type with a coating that reduces heat coming in from the sun.