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California Academy of Sciences
New CAS Is a Vision of Green Concrete Beauty
 The
new home of the California Academy of Sciences (CAS) in San Francisco
is a testament to the brilliant convergence of sustainable building
systems and environmentally responsible technologies within a single,
large-scale development.
The CAS home endured decades of public service until the 12-building-museum
suffered extensive damage from the 1989 Loma Prieta earthquake.
The Academy set out not only to rebuild this fascinating exhibition,
but also to offer a world-class example of environmentally superior
construction. CAS is aiming for LEED platinum certification by the
U.S. Green Building Council (USGBC) and would be the largest public
space to achieve this distinction.
The new facility, which will include a planetarium, aquarium and
natural history museum, is scheduled to open during Fall 2008, just
over three years since the groundbreaking in September 2005. At
410,000 square feet, the building will be larger than its predecessor
yet will sit on a smaller footprint, returning an acre of green
space to Golden Gate Park.
 Among
the most striking features is the 197,000 square foot green rooftop.
This living roof will keep the building’s interior temperature
10 degrees cooler than a conventional black tar-and-asphalt roof
therefore reducing the ‘Urban Heat Island’ effect. The
roof will reduce storm water runoff and the collected rainwater
systems will help reduce the usage of potable water by 22 percent.
The award-winning design team of Renzo Piano, Chong Partners and
ARUP Design incorporated green elements into all aspects of the
design and construction. All materials used on the project were
reclaimed or recycled ranging from recycled blue jeans for insulation
to recycled concrete. The building has already been recognized by
the EPA with a regional Environmental Award and was the North American
winner of the silver Holcim Award for Sustainable Construction.
Beyond the traditional role of concrete framing as a structural
skeleton, concrete is an integral part of the building’s mechanical
system and capitalizes its inherent thermal mass. The interior spaces
are thermally controlled using the excess heat from electrical systems
and natural light is able to reach 90 percent of the space. The
natural ventilation system uses computerized air-circulators and
is complemented by automated light controls designed to respond
to exterior lighting changes.
The 35,000 cubic yards of concrete is essential to the special
needs of the Academy’s exhibits. For example, the complex
geometry of the aquarium was molded into shape with cast-in-place
concrete. As the movable exhibit shelving rides on rails, the stiff
concrete support system accomplishes the augmented (L/720) deflection
criteria. High-end exposed concrete walls serve as the architectural
finish of the exhibit halls. Central Concrete Supply was able to
provide quality concrete at competitive prices that met the complex
need for environmental friendliness and durability. The concrete
mix achieved the ultra-low shrinkage requirements and incorporated
50 percent supplementary cementitious materials such as fly ash
and slag. These industrial by-products would otherwise be destined
for a landfill. The use of locally extracted aggregates for the
concrete mix is a major contributing factor in the quest for a LEED
platinum rating, as LEED certification favors regionally available
building materials.
The new building demonstrates a new standard in energy efficient,
environmentally consciousness and sustainable engineering systems
in a public, landmark building.
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