California Academy of Sciences
Using light as a primary element of design, Piano shines away any dark stereotype of a natural history museum with dim musty halls cloistering insular scientists.
Even the glass chosen for the project, with a low iron content to maximize transparency, aptly supports the museum's mission of exploring, explaining, and preserving the natural world. The high-performance glass transmits daylight to most occupied spaces while also minimizing heat gain. Piano's extensive use of glass also serves as a reminder of nature's inherent fragility.
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The California Academy of Sciences was founded in 1853, the first such scientific institution in the West. It moved to Golden Gate Park in 1916, growing over the next 60 years to encompass an expanding program and a cluster of 12 interdependent structures.
The 1989 Loma Prieta earthquake significantly damaged some of the structures, with Bird Hall and the Steinhart Aquarium suffering the most damage. After considering repair and seismic retrofitting of the complex, the Academy's board of trustees in 1999 decided to instead build a single, sustainable new building on the Golden Gate Park site.
Renzo Piano appeared at the selection interview alone, armed with only a green marker and a sincere desire to understand the organization's mission. After contemplating the existing buildings from the steps of the nearby de Young Museum and taking in the view from the roof of the Academy, Piano sketched a sinuous roofline that echoed the hilly topography of San Francisco. With this design concept he clinched the deal for the project.
To allow for demolition and construction to occur, the Academy moved to a small temporary home near downtown for four years.
Raising the Plane
The Academy project called for integrating the many functions of the previous 12-building facility into a coherent whole.
Piano started with the elegant concept of a pavilion that blends seamlessly into the park setting. He has described the museum as "cutting the ground plane of a park and lifting it 38 feet [12 meters] into the air."
The undulating roof is planted with nine species of native California plants, which are expected to attract native wildlife. Accessible via elevator, the 2.5-acre (one-hectare) roof also serves as a living classroom, providing a forum for educating visitors about sustainable design and California's ecosystems.
The slopes of the "hills" on the roof draw cool air into the central plaza area and then naturally ventilate the surrounding exhibition spaces. Mechanized skylights open and close to regulate the accumulation of heat inside the building over the course of the day. Natural light reaches the living rainforest inside and the coral reef beneath it.
Energy usage at the new Academy is expected to be 30 to 35 percent less than that of a typical building its size. Contributing to that are the six inches (15 centimeters) of soil on the living roof, which insulate the building, keeping interior temperatures ten degrees Fahrenheit (six degrees Celsius) cooler than a conventional roof.
The soil is also expected to absorb 98 percent of stormwater, keeping approximately 3.6 million gallons (13.6 million liters) of runoff annually from flowing into the nearby Pacific Ocean.
The border of the pavilion is covered by 60,000 photovoltaic cells that will generate five to ten percent of the energy needed for the building's operation.
New Structure, Old Elements
In the words of Kang Kiang, the former project manager with Chong Partners, the museum design can be described as a "table" that rests on the "legs" of four similarly proportioned pavilions. In between the pavilions on all four sides of the building are curtain walls that ease navigation through the interior.
A network of tension cables, described by Piano as a spider web, is connected to a ring truss that secures the building structurally. In the event of an earthquake, all the glass pieces of the plaza's ceiling have been designed with patch fitting to move six inches (15 centimeters) in any direction without breaking. The reinforced concrete walls that support the four pavilion "legs" provide shear walls for the transfer of horizontal forces.
The "leg" on the northeast side of the building preserves two limestone walls from African Hall, a Beaux-Arts-style structure built in 1934. Inside, the building's popular dioramas and ceiling details were painstakingly reproduced from the original. A new space at the far end of the hall houses a colony of live African penguins.
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