state's 2019 update of energy efficiency standards and ongoing efforts to reduce greenhouse gases. The state's building sector is the second-largest source of greenhouse gas emissions when fossil fuels power plants are factored in. "This is an undeniably historic decision for the state and the U.S.," said Abigail Ross Hopper, president and CEO of the Solar Energy Industries Association, a trade association with about 1,000 member companies. "California has long been our nation's biggest solar champion, and its mass adoption of solar has generated huge economic and environmental benefits, including bringing tens of billions of dollars of investment into the state." News of the nation's most populous state mandating solar on new homes is a win for the solar companies and sent industry stocks higher Wednesday. SunPower added6 percent, Sunrun jumped 4 percent, First Solar added 3 percent and Tesla picked up nearly 2 percent. "Overall, we expect with California's mandate some companies within the solar and broader renewable industry stand to benefit positively, including those who make panels and component parts, as well as those who assist with installation and ensure efficient use of energy," said Dave Fanger, CEO of Swell Investing, holder of solar and related stocks in its Green Tech and Renewable Energy portfolios. The commission's action on new 2019 building energy efficiency standards also applies to everything from current ventilation systems to indoor air quality. California updates the efficiency standards every three years, and the state's ultimate goal is net-zero energy homes that reduces the carbon footprint of buildings and makes