San Francisco will soon become one of the first major cities in the U.S. to require solar power on new buildings. The rule, which received approval from San Francisco's Board of Supervisors this week, is set to go into effect in January 2017. According to the legislation, all new buildings with 10 stories or fewer -- both residential and commercial -- will have to use either solar panels for electricity or a solar system to heat water. The Guardian notes that smaller Californian cities such as Lancaster and Sebastopol already have similar laws in place, but San Francisco is the first large city to adopt the new standard. "In a dense, urban environment, we need to be smart and efficient about how we maximize the use of our space to achieve goals such as promoting renewable energy and improving our environment," Supervisor Scott Wiener said in a statement. Vox has more details.