From the Environmental Protection Agency:

Find Energy Star products for your home – Choosing energy-efficient products can save families about 30% ($400 a year) while reducing our emissions of greenhouse gases. Whether you are looking to replace old appliances, remodel, or buy a new house, you can help. ENERGY STAR is the government’s backed symbol for energy efficiency. The ENERGY STAR label makes it easy to know which products to buy without sacrificing features, style or comfort that today’s consumers expect.

More steps you can take:

• Turn off appliances and lights when you leave the room.
• Use the microwave to cook small meals. (It uses less power than an oven.)
• Purchase “green power” for your home’s electricity. (Contact your power supplier to see where and if it is available.)
• Have leaky air conditioning and refrigeration systems repaired.
• Cut back on air conditioning and heating use if you can.
• Insulate your home, water heater and pipes.