This book provides an overview of middle income households across the United States, which are under significant financial strain, and rising energy bills are a contributor to this stress. Energy efficiency improvements have the potential to provide significant benefits to these households, by lowering bills, increasing the structural integrity of homes, improving health and comfort, and reducing exposure to volatile, and rising, energy prices. Middle income households are also responsible for a third of U.S. residential energy use. Increasing the energy efficiency of their homes would deliver substantial public benefits: reducing power system costs, easing congestion on the grid, and avoiding emissions of greenhouse gases and other pollutants. To achieve those goals, utilities and governments are beginning to look beyond typical residential energy efficiency programs and are turning to programs that improve the energy efficiency of the entire house by sealing the leaks, reducing plug loads, adding insulation, and replacing inefficient heating and cooling systems.