Don't set your thermostat at a colder setting than normal when you turn on your air conditioner. It will NOT cool faster. It WILL cool to a lower temperature than you need and use more energy.
To operate your air conditioner unit more efficiently, turn on your ceiling fans. These fans create air movement across the skin, lowering skin temperature through evaporation. The homeowner can thus raise the A/C thermostat setting up to 4 degrees F without any decrease in comfort. Each degree you raise the thermostat above 78 degrees F you save about 7-8 percent on your electric cooling costs.
Use landscaping, awnings, and overhangs to shade the outside of your house in summer. A shaded house costs less to cool than one in direct sunlight.
When possible, use fans to keep cool instead of an air conditioner. Fans consume only a small fraction of the energy of an air conditioner.
If you plan to leave for a few minutes or more, turn the fan off. Letting it run wastes energy and does nothing to cool the room--in fact, the heat from the motor actually warms the room a little.
Clean the outside condenser coils of your heat pump or central air conditioner.
When it's time to shop for a new air conditioner, select a unit with a high Seasonal Energy Efficiency Ratio (central air units) or energy efficiency Ratio (window units). For humid climates, select a unit that also does a good job of dehumidifying. And don't buy a unit larger than you need.
Set the fan speed of your central air conditioner on high except in very humid weather. When it's humid, set the speed on low; you will get less cooling but more moisture will be removed from the air which will make it feel cooler.
Do not position heat-producing appliances, such as televisions or lamps, near the thermostat that controls your air conditioner. The heat they produce "fools" the thermostat and causes the air conditioner to run longer than necessary.
Take advantage of natural ventilation during the times of the year when this is feasible to reduce air conditioning usage. By opening and closing windows, different parts of a building can be ventilated.
If your ceiling fans are reversible, be sure to adjust the setting at the onset of the cooling season so that the blades turn to create a downdraft.
When purchasing ceiling fans, remember that a 36- or 42-inch fan works best for rooms 12 feet by 12 feet or smaller. A 48- or 52-inch fan works best for rooms up to 12 feet by 18 feet. Two medium-sized fans work best in a room longer than 18 feet.
Consider using a whole-house fan as part of your cooling strategy. A whole-house fan is installed horizontally in the ceiling below the attic. Whole-house fans consume considerably less energy than air conditioners.
Under appropriate weather conditions in the cooling season, use window fans mounted in windows to exhaust hot air that accumulates indoors during the day and, reversed at night, to pull in cooler outdoor air.
Close doors and vents of unused rooms to avoid cooling these areas.
Turn off unnecessary lights and use energy-efficient lights, especially when you have the air conditioner running, because lights generate a significant amount of heat.
Set the thermostat for your central air conditioning system at the highest comfortable setting (78-80 degrees F is recommended). If you normally set it at 72 degrees F, raising it to 78 degrees F should save between 12 and 47 percent in cooling costs, depending on the climate where you live.
Plant trees or shrubs or use other shading devices to shade the air-conditioning unit from direct sunlight. You can increase efficiency by up to 10 percent. But do not block air flow.
Turn off your window air conditioners when you leave a room for several hours.
Keep your cooling system well tuned with periodic maintenance by a professional service person. Ask the service person how the energy efficiency of the system could be increased.