States can set minimum energy efficiency standards for products not covered by mandatory federal standards. The U.S. Department of Energy can also grant states a waiver to allow them to set stronger standards for products covered by existing federal standards. Individual states have set standards for a wide range of different products, ranging from lightbulbs to refrigerators, but many of these standards have since been preempted by federal standards. Learn more about state appliance standards here [1].
Links:
[1] http://www.c2es.org/what_s_being_done/in_the_states/energy_eff_map/detail.cfm