Avoid overcooling. Don’t use or buy more cooling equipment capacity than you actually need. If you decide on central air conditioning, select the most energy-efficient unit that will cool the size space you have. Bigger is not better. A larger unit than you need will cost more to run and may not remove enough humidity from the air, the feature that some consumers like most about air conditioners.
Keep your cooling system well tuned. Have it professionally maintained, and ask how the energy efficiency of the system may be increased. Remember to replace the air filter regularly.
Install a whole-house ventilating fan. This can be put in your attic or in an upstairs window to cool the house, even if you have central air conditioning. According to Consumer Reports, a big fan working under the right conditions can cool and ventilate an entire house for about the energy cost of running an air conditioner in one room.