The perspective of policy makers and pundits too often seems to be one of unending growth of energy consumption that must be met through supply-side options. That ignores, however, the very important role of demand-side energy efficiency in the energy markets. Unlike traditional energy conservation (e.g., “Turn down the thermostat and put on a sweater”), energy efficiency is a technology-driven process that seeks to provide the same level of energy service—the work, comfort, and functionality we obtain from the use of energy—while using less energy supply (e.g., “Add insulation so the furnace doesn't need to run as often to maintain the same comfort level”). Reducing the quantity of energy demanded by customers over time [kilowatt-hours (kWh)] via energy efficiency is a fast-growing segment of the energy industry and has being embraced by utilities, builders, business and homeowners, politicians, and other stakeholders around the country.