In the United States, direct energy use in buildings accounts for 39% of carbon dioxide emissions per year—more than any other sector. Buildings contribute to a changing climate and warming of the earth in ways that will significantly affect future generations. Zero net energy (ZNE) buildings are a practical and cost-effective way to reduce our energy needs, employ clean solar and wind technologies, protect the environment, and improve our lives. Interest in ZNE buildings, which produce as much energy as they use over the course of a year, has been growing rapidly.