Replace 4 lightbulbs with compact fluorescent lightbulbs.

Eliminate 1800 pounds of carbon dioxide emissions over the life of the bulbs.

More actions you can take:

• Buy Energy Star products and appliances.
• Turn lights and computers off when they are not in use.
• Clean your refrigerator coils. Dust on
  the coils located in the back of a
  refrigerator makes it less efficient.
• Change or clean the filters in your air conditioners and heaters.
• Use sleep mode on your computers at home and at the office. Turn them off at night.
• Open the dishwasher and air-dry dishes instead of using the hot air dry cycle.Only run the machine with full loads.
• Dry your laundry on a clothesline.
• Wash clothes on warm or cold cycle, not hot.Wash only full loads.
• Turn down your hot water heater to 120F.
• Shorten showers by a few minutes to conserve hot water.
• Adjust thermostat when you leave the house (10F down in winter, 10F up in summer).
• Keep up with basic furnace maintenance. Have it professionally tuned and cleaned, and replace air filters regularly.
• Cook more efficiently. Cover pots, use a pressure cooker when appropriate, keep burners clean, cook several dishes at a time in the oven, and use a microwave to heat food.
• Keep drapes or blinds closed at night in winter and during the day in the summer to reduce heating and cooling needs.
• Install faucet aerators in sinks to reduce hot water use.
• Insulate the 4 ft of hot water pipes closest to hot water heater.
• Insulate all hot water pipes.
• Caulk and weatherstrip all your doors and windows.
• Have a professional seal your heating ducts to reduce the loss of heated air.
• Install a programmable thermostat.
• Replace appliances--dishwashers, refrigerators, washing machines--that are more 10 years old with an Energy Star model. The older models are less efficient than newer ones.
• Replace your old furnace with efficient Energy Star model.
• Install a solar hot water heater.
• Eat one less beef meal per week. It takes far more energy to produce meat for consumption than it does to raise a crop.