The Living Roof of the Ortega Branch Library is the seventh San Francisco Public Library branch built to Silver certification standards under the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) rating system. This living roof with native species plantings reduces the library's carbon footprint by reducing heat island effects and capturing rain water. With creative roofing like this (and exterior paving materials) we reduce the heat island effect of this building (i.e. thermal gradient differences between developed and natural areas, if you want to get technical). It’s important to minimize our impact on the micro climate and on wildlife habitat. We selected native and adapted plants that are well-suited to our climate, and require less water than traditional ground covers such as grass..