Green Roofs

California Academy of Sciences

By: Andrew Ewing

ENVIRONMENTAL: The undulating roofline will draw cool air into the open piazza at the center of the building, naturally ventilating the surrounding exhibit spaces.  Because the living roof absorbs rain water, it prevents up to 3.6 million gallons of runoff from draining into the ecosystem.  This roof also has been planted with 9 native plant species which make up the 1.7 million plants that make up the roof.  These native plants will form a natural habitat and a large number of native species to form a mini-ecosystem.  “The planted 2.5 acres; it is now the largest swath of native vegetation in San Francisco.

·        AESTHETIC: The green roof connects two old buildings with a new structure, which forms a new structure. It connects visually with the Golden Park.  “Renzo Piano’s masterstroke of design lies in making the park’s environment such a visible part of the building itself.  The rooftop’s seven undulating green hillocks pay homage to the iconic topography of San Francisco and blur the boundary between building and parkland.”

·        FUNCTIONAL: There is an open-air observation terrace which enables visitors to get a close-up look at the roof’s lush canopy of plants.  The plants seen from this view are some of the densest concentrations of native wildflowers in San Francisco.  It also allows the public close access to several types of birds and insects.  Skylights are placed on the roof.  These open and close throughout the day, which allows sunlight to reach exhibit spaces below.

·        SOCIAL: The green roof connects a planetarium, museum, aquarium, research departments, indoor rainforest, and coral reef exhibit.  The roof serves as a structure that connects all these into one building.  It also has an observation deck on the roof that allows a space up top to be used.

·        EDUCATIONAL: The biodegradable modular green roof system was developed specifically for this project.  Research over 3 years was studied on green roof systems that helped progress this sustainable practice not only for this project but green roofs in general.  The whole roof is an educational piece to everyone.  This structure teaches the visitors about native plantings as well as about native birds and insects.

·        ECONOMICAL: There was a 3 year research period where a series of different types of living roofs were constructed to test how indigenous plants, as well as soil retention and drainage techniques were chosen.  The green roof will provide a thermal insulating layer for the building, reducing standard levels of heat absorption and decreasing the cooling load.  “Surrounding the Living Roof is a large glass canopy with a decorative band of 60,000 photovoltaic cells. These solar panels will generate approximately 213,000 kilowatt-hours of energy per year and provide up to 10% of the Academy’s electricity need.  The use of solar power will prevent the release of 405,000 pounds of gas emission into the air.  The green roof also keeps the building’s interior an average of 10 degrees cooler than a standard roof would.

·        PSYCHOLOGICAL: The whole roof is created to eliminate the hard space typically created by roofs.  When the user is looking out from the rooftop viewing area the green roof blends in with the surrounding landscape.

IMAGES:

ADDITIONAL INFORMATION: “BioTray” created 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.

EVALUATION OF THE PROJECT: I really like this project.  I think it is a very creative and successful design that blends architectural design with sustainable practices.  From everything I found it seems to be well received in the community and is producing as expected.  This project is an excellent case study of the potential of roof gardens.