ABSTRACT Emerging new technologies can drastically reduce the energy consumption of buildings in the United States. In this article we look at overall energy usage, where our supply sources for energy emanate, and how they are used throughout the United States in the different demand sectors. With a goal to reduce buildings' energy consumption to zero energy, different building components are discussed, including the building envelope, HVAC, fenestration, lighting, energy recovery, hydroelectrics, photovoltaics, and energy recovery. We discuss the different components that are commercially available today.