If you have central air conditioning, do not close vents in unused rooms This could increase pressure and cause leaks in your ducts This does not apply to homes or apartments with window units where closing off unused rooms will reduce cooling costs and increase comfort Consider new high efficiency air conditioners and heat pumps They use up to 40% less electricity than older models for the same amount of running time Clean your AC's condenser/evaporator coils at the beginning of the season Clean coils lower your energy costs, extend the unit's life and provide cleaner air for you to breathe The fin coils on the outside AC unit can be washed with a hose Coils on inside units may be difficult to get to and usually require a trained technician. Upgrade to a Digital Programmable Thermostat! Digital Thermostats can save you hundreds of dollars per year in energy costs.