Programmable thermostats are no longer part of the federal Energy Star program

The U.S. Environmental Protection Agency recently announced that it will suspend its Energy Star specification for programmable thermostats effective December 31, 2009. Any models manufactured after that date cannot bear the Energy Star label; manufacturers will have several months to update their Web sites and promotional material.

While that suspension might seem odd—using a programmable thermostat can help you cut your cooling and heating costs by up to 20 percent—it follows investigations by the EPA into concerns with programmable thermostats, including difficulties in using these devices. Indeed, as we found in our October 2007 report on programmable thermostats, the controls on these devices are sometimes so confusing that one could cause your energy costs to go up. The EPA administers Energy Star with the U.S. Department of Energy.

The EPA also questioned the lack of differentiation between Energy Star-qualified models and nonqualifying ones; the scant evidence showing that programmable thermostats conserve energy on a consistent, nationwide basis; and the fact that savings ultimately come down to consumer behavior—even the best programmable thermostat won't save energy if you doesn't use it properly. Programmable thermostats had been part of Energy Star since 1995.

The EPA will continue to educate the public about the savings associated lowering a thermostat in winter or raising it in summer, particularly when the home is unoccupied, a process that is automated with programmable thermostats. The agency will also work with manufacturers and other interested parties on a new Energy Star specification.

The EPA's decision doesn't mean you should abandon using a programmable thermostat. To find the right model for your home, read our buying advice and check out the ratings of more than two dozen models (available to subscribers).—Daniel DiClerico | e-mail | Twitter | Forums | Facebook

Essential information: Try these 25 ways to save energy. And for advice on energy-efficient ways to stay cool this summer, read our July 2009 report on air conditioning (available to subscribers).