A report released Monday rated Idaho as the most improved state in this category, moving from 25th two years ago to 13th. California, Connecticut and Oregon were followed in the Top 10 by Vermont, New York and Washington state. Also, Minnesota and Massachusetts were tied, and New Jersey made the top tier of states.

The American Council for an Energy-Efficient Economy rated the states on "a wide range of the proven effective and readily available efficiency strategies." Among areas examined were building codes, transportation and land-use policies, utilities' efficiency programs, financial incentives and support for research.