CAS Is a Vision of Green Concrete Beauty

casThe home of the California Academy of Sciences (CAS) in San Francisco, California, 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 was awarded the Leadership in Energy and Environmental Design LEED® gold certification by the United States Green Building Council (USGBC). 

The facility, includes a planetarium, aquarium and natural history museum. At 410,000 square feet, the building is larger than its predecessor yet will sit on a smaller footprint, returning an acre of green space to Golden Gate Park.

cas_roofAmong the most striking features is the 197,000-square-foot green rooftop. This living roof will keep the building’s interior temperature 10 degrees Fahrenheit cooler than a conventional black tar-and-asphalt roof therefore reducing the ‘Urban Heat Island’ effect. The roof reduces storm water runoff and the collected rainwater systems helps reduce the usage of potable water by 22 percent.

The award-winning design team of Fernau and Hartman of Berkely, California, 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 Environmental Protection Association (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 provided 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 new building demonstrates a new standard in energy efficient, environmentally consciousness and sustainable engineering systems in a public, landmark building.

Credits

Owner:
California Academy of Sciences, San Francisco, California

Architect:
Skidmore, Owings, & Merrill, San Francisco, California
Fernau and Hartman, Berkeley, California
Renzo Piano Building Workshop, New York, New York 

Engineer:
ARUP Engineering, San Francisco, California 

Concrete Contractor:
Webcor Concrete, San Francisco, California

General Contractor:
Webcor Builders, San Francisco, California 
Swinerton Builders, San Francisco, California

Concrete Supplier:
Central Concrete Supply, San Francisco, California