Living Roof in Bloom

The more typical black tar-and-asphalt building rooftop leads to a phenomenon called the “Urban Heat Island” effect. The endless swath of black rooftops and pavement trap heat, causing cities to be 6 to 10 degrees warmer than outlying greenbelt areas. One-sixth of all electricity consumed in the U.S. goes to cool buildings. The Academy's green rooftop will keep the building's interior an average of 10 degrees cooler than a standard roof would. The plants also transform carbon dioxide into oxygen, capture rainwater, and reduce energy needs for heating and cooling.
http://www.calacademy.org/academy/building/index.php