It’s one of the most expansive and one of the most complex living roofs ever designed- the 197,000-square-foot rooftop is home to 1.7 million native plants-, but the crown on the new California Academy of Sciences is more than simply a home for native plant species. It’s also an integral part of the building design.

Up here there are weather stations that report on wind, rain, and temperature changes to a central computer. This feedback is used to open and shut the roof’s skylights (as well as the building’s windows) to create automated passive ventilation. In other words, this smart system means the building doesn’t need air conditioning (The skylights are also computer-controlled to provide natural daylighting where needed most).

The green canopy also helps the building regulate its own temperature. In summer, it helps avoid the “Urban Heat Island” effect (black and paved rooftops cause cities to be 6-10 degrees warmed) and keeps the building 10 degrees cooler than a standard roof. In winter, it helps keep the building warm: the 6 inches of soil substrate provide natural insulation.

Besides providing a home to carefully selected native plants- and at least 70 species of insects (with plans to introduce endangered varieties)-, the Academy’s earthen roof absorbs stormwater, preventing 3.6 million gallons of runoff annually.

In this video, the Academy’s Aaron Pope takes up the top of the new museum where he shows us the very hilly green roof that not only creates microclimates for specific plants but was architect Renzo Piano’s homage to the seven hills of San Francisco.