I love my city.
Construction is not a sexy area of climate policy, but it is one in which huge gains can be made for relatively little cost. Existing technologies, such as solar water heating, could cut greenhouse gas emissions from a building by almost one-third, for example. Yet authorities regulating the housing booms in places like the American south-west and many cities across China have done little to promote such measures.
San Francisco may now provide a template for change. Potential homes and offices will be rated on measures including the quality of insulation and the amount of recycled materials used in their construction. Only projects that score enough points will be allowed to go ahead.