Assembling a 197,000-square-foot rooftop to accommodate a living tapestry of native plant species is challenging enough. Add to that the technical problems posed by the roof’s extreme dips and slopes. How to keep the plants and soil from sliding off? The solution was to use 50,000 porous, biodegradable trays made from tree sap and coconut husks as containers for the vegetation. These trays line the rooftop like tile, yet enable the roots to grow and interlock, binding the trays together like patchwork.

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.

An open-air observation terrace will enable visitors to get a close-up look at the roof’s lush canopy of plants. The view will encompass the densest concentration of native wildflowers in San Francisco. The expansive vista will also become an ideal location for watching Northern California’s birds, butterflies and insects. Skylights above the larger domes will open and close throughout the day, enabling sunlight to reach the exhibits below. The steep slopes of the rooftop's hills will draw cool air into the open piazza at the center of the building. Weather stations on the roof will monitor wind, rain, and changes in temperature to help inform the automated passive ventilation systems.

Up on the Roof