Buildings and homes use more than 73% of the electrical energy consumed in the United States. They also consume 40% of the nation’s total energy, with an annual energy bill of $430 billion. These energy bills can be cost effectively reduced by 20%–50% or more through various energy-efficient technologies and techniques. The Building Technologies Office (BTO) will continue to develop and demonstrate advanced building efficiency technologies and practices to make buildings in the United States more efficient, affordable, and comfortable.