Electric and natural gas energy efficiency in the United States is pursued through a diverse mix of policies and programmatic efforts, which support and supplement private investments by individuals and businesses. These efforts include federal and state minimum efficiency standards for electric and gas end-use products; state building energy codes; a national efficiency labelling program (ENERGY STAR®); tax credits; and a broad array of largely incentive-based programs for consumers, funded primarily by electric and natural gas utility customers. This book provides information on projected spending and savings of the future of utility customer-funded energy efficiency programs in the United States; and discusses the shifting landscape of ratepayer-funded energy efficiency in the United States.