Improving the energy efficiency of homes, businesses, schools, governments, and industries which consume more than 70 percent of the natural gas and electricity used in the United States--is often the most cost-effective option for addressing the challenges of high energy prices, energy security and independence, environmental concerns, and global climate change in the near term. Other technologies that address these challenges include renewable energy (e.g., solar thermal, solar photovoltaic, wind, hydro, biomass), clean distributed generation, and combined heat and power (CHP). Despite a range of well-documented benefits, several persistent barriers limit greater investment in clean energy. Focused policies are necessary to overcome barriers and enable these resources to play an increasing role in meeting our nation's energy needs.