A better way to build

With visions of solar-paneled walls, thermal chimneys and wind turbines, San Francisco hopes to set the bar high for public buildings with its new government office tower. The cost of the green improvements will run the total for the building up about 9 percent. Here's one reason city leaders might see it as a worthwhile investment: A recent study in New York City found that buildings were the largest contributor to greenhouse gas emissions, and cities worldwide are recognizing that building codes and renovations will be key to curbing global warming. San Francisco wants to set an example.