In San Francisco, fog is more prevalent than sunshine. Hearty grasses may thrive, but the dry ecosystem is hardly an oasis for lush, tropical vegetation. But beneath one man-made, grassy hilltop, the Amazonian trees and plants in the ' new "Living Rainforest" exhibit are thriving--without an overload of human-produced energy.
The four-story domed rainforest exhibit is the centerpiece of the California Academy of Sciences' new energy-efficient headquarters in Golden Gate Park. The building--also home to a planetarium and aquarium beneath a 197,000-sq.-foot living roof that's covered with native plants--has been under construction for the past three years and will open to the public in September.
"Rainforests are the most diverse and threatened ecosystems on the planet," says Bart Shepherd, curator of the rainforest exhibit, a permanent fixture of the museum. "Cal Academy wanted to bring the beauty and diversity to our guests, many of whom will never have the opportunity to visit rainforests in the wild." The Living Rainforest will showcase plants and animals from rainforests in Borneo, Madagascar, Costa Rica and the Amazon.
Both the exhibit and building had to be methodically planned and engineered to achieve maximum energy efficiency. Step one for the Academy was identifying the best location in the building for the rainforest, which took a year-long study of the solar energy striking the property. Using the results, engineers positioned the rainforest dome so that its 80 skylights receive the most direct sunlight possible.
But even with correct positioning, the light reaching the exhibit is still only about one-quarter of the amount that shines on equatorial rainforests. The site sees only 75 cloudless days per year, so the curators were careful in choosing the plant species to be include in the dome. "The larger trees--Mahogany, Peach Palm, Black Olive, Brazilian Beautyleaf and Water Chestnut--were selected based on their ability to thrive with available light levels in this exhibit," Shepherd says. Metal-halide lamps supplement the natural solar energy.
Aside from light, these ecosystems rely on heat and humidity. A 100,000-gallon tank, which houses animals including bigheaded turtles, angelfish and armored catfish native to flooded Amazonian forests is maintained at 80 degrees, and doubles as a temperature and humidity regulator. Radiant floor heating maintains the exhibit's 82-85 degree temperature on cooler days. A portion of the power for environmental control is provided by 60,000 photovoltaic cells installed on the building's roof.
With additional eco-friendly features like recycled denim insulation, recycled steel for structural support and roof skylights that release hot air to reduce cooling needs, the academy aims to achieve platinum certification from the Leadership in Energy and Environmental Design Green Building Rating System. "As scientists, we are the champions of rational thought based upon empirical evidence," Shepard says. "By embracing green building practices and emphasizing sustainability, we hope to inspire visitors to make smart choices in their own lives."