San Francisco may soon boast the greenest buildings in the US. Last week, the local government took a decisive step towards agreeing what are probably the toughest environmental construction standards in the country. Families and companies planning to build offices and homes will be required to earn green points by introducing energy and water-saving measures - or they risk losing their construction permits.
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.
The rules were passed on 19 March by the city's Building Inspection Commission. They are expected to be agreed by senior officials in the next few months and go into operation next year. During their first year in force, the rules are likely to affect the construction of about 75,000 square metres of office space and 1000 new apartments.