The tool also provides you with the kilowatt-hour yield for each item in batches, loads, and in hours of use. For example, 1 kilowatt of electricity will run an answering machine for 1,000 hours but an electric furnace for only 6 minutes.

In some of the available views and for products with a green star, Home Appliance Energy Use can also give you the estimated payback time when you replace an older device with a higher-efficiency Energy Star-qualified model. A Hawaii resident replacing a pre-1994 dishwasher with an Energy Star model would get a return on that investment in three years compared with a 10-year payback time for someone in Washington state, where electricity costs a lot less.

The Home Appliance Energy Use is another step by GE to position itself as a leader in energy efficiency, part of efforts like the recent green campaign on some NBC Universal shows. The company has rolled out the GeoSpring electric heat-pump water heater, which our preliminary tests have found could save you a lot of money over a standard electric water heater; unveiled the prototype of its energy-management system and smart appliances; and promoted the smart grid.

Using the GE Home Appliance Energy Use tool isn't going to save you money on its own but perhaps the knowledge of how much energy each device consumes will motivate you and your family to waste less electricity—don't leave your plasma TV (339 watts) and video-game player (195 watts) on when you're done using them. And getting a sense of payback periods for new equipment could convince you to replace an older model with a new one sooner than later.

—Daniel DiClerico

Essential information: If you're going to replace appliances, take advantage of cash for appliance rebates. Stay on top of efficiency news by following us at Twitter.com/CRHomegarden and visiting our Energy Saving & Green Living guide.