The Energy Department is considering a stiffening of pending federal energy-efficiency standards for appliances, Energy Secretary Steven Chu said today.

"I am going to be looking at those because I have become more convinced that they are not as aggressive as they could be," Chu said at a conference held by the Alliance to Save Energy. "So we will look at making them more aggressive."

Chu did not list any specific pending standards that may be toughened.

According to the nonprofit Appliance Standards Awareness Project, DOE's deadlines call for final rules this month for ranges and ovens and commercial clothes washers, with final standards for multiple types of lamps due in June.

The group argues that strong standards for fluorescent tube light bulbs and reflector light bulbs could save enough kilowatt-hours by 2020 to meet the needs of 5 million households. But the group and other efficiency advocates have argued that a Bush administration proposal in January was weak.

There are also a host of proposed standards due later this year, for products such as water heaters and pool heaters.

Chu stressed the key role that energy efficiency in appliances and buildings should play in curbing greenhouse gas emissions. He also emphasized the need to ensure that consumers see efficient appliances and home materials as choices that will ultimately save them money.

Chu also suggested a change in the Energy Star labeling program run jointly by U.S. EPA and DOE.

Floating the idea of a "superstar" category of perhaps the top 5 to 10 percent best performers, Chu said this would allow manufacturers to claim that their products would ultimately save consumers the most money despite higher up-front costs.