Known as one of the country’s more progressive cities in terms of implementing sustainable strategies across all levels of government, it should be no surprise that the California Academy of Sciences (CAS), in San Francisco, is one of the world’s most innovative museum building programs. Now complete (after almost a decade of planning) and expected to earn a LEED Platinum certification from the U.S. Green Building Council, CAS in the city’s Golden Gate Park is topped with a 2.5-acre living roof and employs a wide range of energy-saving materials and technologies. Designed by Pritzker Prize winner Renzo Piano, the facility stands as an embodiment of the CAS’ mission to explore, explain and protect the natural world.

“Our goal was to create a new facility that would not only hold powerful exhibits but serve as one itself, inspiring visitors to conserve natural resources and help sustain the diversity of life on Earth,” said CAS Executive Director Dr. Gregory Farrington.

The living roof, which reduces stormwater runoff by up to 3.6 million gallons of water per year, includes an observation deck, allowing visitors to admire the rooftop wildlife haven and learn about the benefits of this sustainable feature.

New Standards for Sustainable Architecture

CAS is one of 10 pilot green building projects of the San Francisco Department of the Environment, part of a vanguard initiative to develop models for workable, sustainable public architecture. Designed to be the greenest museum in the world, CAS optimizes the use of resources, minimizes environmental impacts, and serves as an educational model by demonstrating how humans can live and work in environmentally responsible ways. The facility integrates architecture and landscape, and helps to set a new standard for energy efficiency and environmentally responsible engineering systems in a public, architecturally distinguished building. “We’re not here to disrupt the environment; we’re here to accentuate,” said Eric Ko, CAS engineer of record, Arup.

In Piano’s design, the environmentally sensitive components of the building are featured, rather than hidden. The roof is bordered by a glass canopy containing nearly 60,000 photovoltaic (PV) cells, which will produce up to 10 percent of CAS’  annual energy needs. These PV cells are clearly visible in the glass canopy, providing both shade and visual interest for the visitors below. Additional green features throughout the building are highlighted with informational signage.

Employing a wide range of green technologies and strategies, CAS will use about 30 to 35 percent less energy each year than a typical building of its size.

The solar canopy around the perimeter of the roof, containing 60,000 photovoltaic cells, will supply up to 10 percent of the CAS’ energy needs.

Heat and Humidity

Multiple environmentally friendly and energy efficient technologies are utilized within the facility to reduce the building’s footprint. Radiant floor heating by Uponor reduces energy needs by 5 to 10 percent. Heat recovery systems capture and utilize heat produced by HVAC equipment, reducing heating energy use. The planted roof provides a thermal insulating layer for the building, reducing energy needs for air-conditioning.

High-performance glass is used throughout the building, reducing standard levels of heat absorption and decreasing the cooling load. Reverse osmosis humidification systems are used to keep the research collections at a constant humidity level, reducing energy consumption for humidification by 95 percent.

Natural Light and Ventilation

At least 90 percent of regularly occupied spaces have access to daylight and outside views, reducing energy use and heat gain from electric lighting. The skylights are strategically placed to allow natural sunlight to reach the living rainforest and coral reef.

Motorized windows automatically open and shut to allow cool air into the building. Operable windows are also employed in staff offices. Photosensors in the lighting system automatically dim artificial lights in response to daylight penetration, reducing the energy necessary to illuminate interior spaces.

Renewable Energy

A solar canopy around the perimeter of the roof containing 60,000 SunPower high-efficiency solar cells encapsulated in 720 custom-built glass panels will supply clean energy and prevent the release of greenhouse gas emissions. The multi-crystalline cells are some of the most energy efficient cells on the market, achieving at least 20 percent efficiency. Sensor faucets in the bathrooms charge themselves with each use; flowing water causes an internal turbine to generate power and charge the battery pack.

Polished concrete was selected by architect Renzo Piano as a sustainable flooring option. Perfect Polish assembled a 10-man polishing crew scheduled in two shifts, seven days a week for eight to 10 weeks to ensure the almost 200,000-square-foot project was completed on time.  >> Photo courtesy of Perfect Polish.

Water Efficiency

By absorbing rainwater, CAS’ living roof will prevent up to 3.6 million gallons of runoff from carrying pollutants into the ecosystem each year (about 98 percent of all stormwater). Reclaimed water from the City of San Francisco will be used to flush the toilets, reducing the use of potable water for wastewater conveyance by 90 percent.

Low-flow fixtures and the use of reclaimed water will reduce overall potable water use by 78 percent.  Saltwater for the aquarium is piped in from the Pacific Ocean, minimizing the use of potable water for aquarium systems. Nitrate wastes are purified with natural systems, ensuring that aquarium water can be recycled.

Recycled Building Materials

More than 90 percent of the demolition waste from the old CAS structure was recycled. Concrete and steel were reused in local roadside construction projects and recycled onsite, respectively. At least 50 percent of the wood in the CAS facility was sustainably harvested and certified by the Forest Stewardship Council. Recycled steel was used for 100 percent of the building’s structural steel; the steel includes 95 percent recycled content.

The Bonded Logic insulation in the building’s walls is made from recycled blue jeans and contains 85 percent post-industrial recycled content.

All concrete contains 30 percent fly ash, a by-product of coal-fired power plants. It also contains 20 percent slag, a waste product from metal smelting. This use of recycled content prevented the release of more than 5,375 tons of carbon emissions.

The Living Roof

A new link in an ecological corridor for wildlife, the living roof on CAS is planted with nine native California species that will not require artificial irrigation. The planted area measures 2.5 acres; it is, as of now, the largest concentration of native vegetation in San Francisco. Approximately 1.7 million native plants blanket the living roof and will provide habitat for a wide variety of wildlife. 

Energy Efficiency                     

The CAS is designed to consume 30 percent less energy than required by federal code. Fifty-five thousand square feet of photovoltaic cells in the roof supply almost 213,000 kWh of energy and prevent the release of more than 405,000 pounds of greenhouse gas emissions annually. The planted roof will provide a thermal insulating layer for the building that will help prevent overheating during the summer months and reduce energy needs for air-conditioning.


The above information was compiled by Sustainable Facility and ED+C editorial staff. For more information, visit www.calacademy.org  and www.arup.com.

Sidebar: California Academy of Sciences

Location: San Francisco

Size: 410,000 square feet

Opened: September 27, 2008

Project Costs: $482 million


Project Team

Owner: California Academy of Sciences Architecture: Renzo Piano Building Workshop (Genoa, Italy) in collaboration with Stantec Architecture (formerly Chong Partners Architecture / San Francisco)

Engineering and Sustainability Consulting: Arup

Living Roof: Rana Creek

Landscape Architecture: SWA Group

General Contractor: Webcor Builders

Project Management: DRY and Associates


Interior Products

Convenience Products/Clayton Corp: Seal-Krete Original Waterproofing Primer/Sealer

Dow Corning: Silicone Sealant

Monokote: Firebond Concentrate

Flame Control Coatings, LLC: 10-10A, 30-30

Sherwin Williams Armorseal Crack Filler

AD Fire Protection Systems: A/D Firefilm III

Sherwin Williams Epoxy: Macropoxy 646 Fast Cure Epoxy

Constantine: Agave Trim-Line Broadloom Carpet

Fisher Hamilton: Composite Wood + Agrifiber Products

Tamco Steel: RPS Regional Steel

Bonded Logic: Cotton Insulation

Owens Corning: Foamulac Insulation

Cotton Metal Inc: HM Doors & Frames

Nucor: Coiling Smoke Doors

BMI Products: Plaster

GP Tough: Drywall

Owens Corning: FSK Insulation

WR Grace: Fireproofing

Cemco: Metal Studs

Armstrong: Acoustic Ceiling Grid

Rana Creek Nursery: Landscape Materials

RPS – Regional Steel: Concrete Reinforcing

Stiles, Inc.: HM Doors

Maxit: Plaster

GP: Drywall

USG: Taping Mud

Marshfield Doorsystems: SmartWood doors

Uponor: Radiant Floor System

Perfect Polish: Polished Concrete Flooring


Exterior & Structural Products

Sherwin Williams: High Solids Polyurethane

Nucor-Yamato Steel: Structural Steel

ACH Technologies: Geofoam

Open Energy Corp.: SolarSave Architectural PV Glass by Suntech

PPG Industries: Starphire Ultra-Clear Glass

SunPower: Solar Cells

American Hydrotech: Monolithic Membrane 6125 and Garden Roof Assembly

Sidebar: Materials & Sources

HVAC / Mechanical

Chilled water is generated by three 240-ton McQuay centrifugal chillers and circulated by a constant flow primary / variable flow secondary pumping system.

Condenser water is cooled via three Baltimore Aircoil closed-circuit, indirect evaporative cooling towers. While most of the cooled tower water feeds directly into the chiller condensers, some is routed through the building to serve AHU coils and to absorb heat rejected from refrigerators and freezers.

Six 2,000 MBtuh condensing boilers from HydroTherm generate heating hot water, which is then distributed via a variable flow, primary only pumping system.

Sixteen custom Governair AHUs have been strategically located within internal mechanical rooms — some spanning multiple floors — so as to avoid interrupting the green roof. These units, in conjunction with an array of variable and constant volume air delivery systems, provide ventilation and comfort conditioning to most of the spaces.

Arup used its own thermal analysis software (ROOM) to determine exhibit area surface temperatures, which were then used as input to STAR-CD computational fluid dynamics software.

As the building design was refined, Arup used EnergyPlus energy simulation software to evaluate thermal and airflow behavior of the exhibit hall at design conditions.

The radiant floor is based on an Uponor system built up over a base concrete slab covered by an inch of rigid insulation. Support rails rest on 1 in. strips of insulation and hold 5/8 in. dia hePEX plus tubing.


For more information on the mechanical systems, visit www.esmagazine.com. Paul Switenki, P.E., a mechanical engineer with Arup, authored “Looking Radiant In Green” in the August 2008 issue of Engineered Systems.