There are currently 130 million homes in the United States—and their combined residential energy usage accounts for 20 percent of the nation’s greenhouse gas emissions. Studies have consistently found that nationwide energy efficiency upgrades would not only significantly reduce emissions and create green jobs, but would pay for themselves. According to “Recovery Through Retrofit,” a recently released White House report that lays out the groundwork for building a sustainable home retro fit industry, existing techniques and technologies in retrofitting can reduce energy usage by up to 40 percent in a given home, potentially saving some $21 billion annually in home energy bills.