Make sure your appliances and heating and cooling systems are properly maintained (ie: filters changed, ducts tested for leaks, appliances cleaned for maximum efficiency and seals tested for leaks). Ducts that leak heated air into unheated spaces can add hundreds of dollars a year to your heating and cooling bills.

Remember, close your chute: We mean your chimney flue. When the fireplace is not in use, keep the flue damper tightly closed. A chimney is designed specifically for smoke to escape, so until you close it, warm air escapes--24 hours a day! Keeping the damper open is like keeping a 48-inch window wide open during the winter. If you never use your fireplace, plug and seal the chimney flue.
Cost: Free

"Texas" air conditioner: If you're sweating to death during the daytime this summer, keep a rotating stock of water-filled gallon containers in your freezer (this will also help your fridge run more efficiently). Put the frozen gallons in a large tub or basin and place a fan behind the tub, aimed at yourself. This is cheap evaporative cooling, folks. For the cost of running your fan, you can stay nice and cool.
Cost: Free

Keeping cool at night: An old trick for staying cool on hot nights is to sleep in a wet t-shirt or under a wet sheet. As the water evaporates throughout the evening, you'll stay cool without running the AC unit.
Cost: Free

Shade trees & vines: Plant trees or shrubs to shade air-conditioning units - but not to block the airflow. A unit operating in the shade uses as much as 10% less electricity than the same one operating in the sun. Shade trees planted in front of west-facing windows can also cut down on the amount of heat that gets into your home during the summer. Carefully positioned trees and vines can save up to 25% of a typical household's energy used for heating and cooling. The Dept. of Energy predicts that just three trees, properly placed around the house, can save an average household between $100 and $250 in heating and cooling energy costs annually. Trees can also deflect winter winds.
Cost: A little more than $20

Programmable thermostats: You can save from 15% to 75% a year on your heating and cooling bills without sacrificing comfort by installing an automatic setback or programmable thermostat. If you have an older home that doesn't have a setback thermostat, you can usually replace your existing wall thermostat with a setback model in a single morning. Only Energy Star-labeled models qualify for utility rebate.
Cost: $50 to $80
Rebates: $20 per unit.

Radiant barrier: Thin, reflective film insulation can reduce air conditioning costs by at least 20% if used as an attic radiant barrier to reflect 97% of the radiant heat. It also helps to keep hot air inside the home during the cool, winter months. Companies that sell radiant barriers include:
Advanced Foil Systems Inc: 800-421-5947
Astro-Foil International: 248-362-2447
Innovative Energy: 800-442-3643
Cost: $20 for 32 sq. ft.

Air conditioning & duct testing: It's a good idea to have your air conditioner and ducts tested, tuned up and sealed to ensure they are running at top efficiency.
Cost varies

Room Air Conditioner: If you're in the market for a new room-sized air conditioner, look for these
Energy Star models which will allow you to qualify for a $50 rebate from the utility.
Rebate: $50

Room Air Conditioner Trade-In Rebate: Now that you've decided to purchase a new room air conditioner, you can get an additional $25 rebate for trading in your old one by calling the Appliance Recycling Center of America at 800-599-5795.
Rebate: $25

Insulation: Increasing your insulation to up to R-38 can reduce heating costs by 5-25%.
Cost: $300 to $800
Rebate: 15¢ sq. ft.

Solar Space Heating: Usually referred to as "radiant heating," a solar, gas or electric hot water system can also be used to provide indoor space heating by running the heated water through baseboards or radiant floor-heating pipes.
Cost: Expensive