From the basement to the roof of the Academy's new building, the choices behind each element of construction reflect a commitment to energy efficiency, reducing the carbon footprint, and preserving the natural world.
The California Academy of Sciences is working with the U.S. Green Building Council to earn a Platinum-level LEED certificate upon inspection of the completed structure. The program, which stands for Leadership in Energy and Environmental Design (LEED), was launched by the council in 1998. The program enables all segments of the building industry to seize the opportunity for leadership by implementing nationally recognized guidelines for sustainable design and construction. In addition to demonstrating the values of the Academy, a LEED-certified building costs less to operate and maintain and—compared to a conventional building—can make a significant impact in reducing carbon emissions.
Points for the coveted LEED certificate are awarded in five key areas: sustainable site development, water savings, energy efficiency, materials selection, and indoor environmental quality. The U.S. Green Building Council offers four levels of LEED certificates (Certified, Silver, Gold and Platinum). They range from Certified, in which 50% of the points are achieved, to Platinum, in which 80% or more of the points are awarded.
When the Academy opens its doors in 2008, the design team anticipates the museum will earn international recognition as the world’s largest LEED Platinum-certified public space.
Soil as Insulation
The LEED program encourages and rewards architects who create innovative, imaginative energy saving solutions. Architect Renzo Piano achieved this in his design for the Living Roof. Not only does the green rooftop canopy visually connect the building to the park landscape, but it also provides significant gains in heating and cooling efficiency. The seven inches of soil substrate on the roof act as natural insulation, and every year will keep approximately 2 million gallons of rainwater from becoming stormwater. The steep slopes of the roof also act as a natural ventilation system, funneling cool air into the open-air plaza on sunny days. The skylights perform as both ambient light sources and a cooling system, automatically opening on warm days to vent hot air from the building.
Solar Energy Panels
Surrounding the Living Roof is a large glass canopy with a decorative band of 60,000 photovoltaic cells. These solar panels will generate approximately 213,000 kilowatt-hours of energy per year and provide up to 10% of the Academy's electricity need. The use of solar power will prevent the release of 405,000 pounds of greenhouse gas emission into the air.
The expansive, floor-to-ceiling walls of glass will enable 90% of the building's interior offices to use lighting from natural sources.
The glass used in these perimeter walls surrounding the public floor were specially constructed with low-iron content. This feature removes a common green tint, providing exceptional clarity. From almost any point inside the museum, visitors will be able to see the park outside in all its seasonal colors.
The building will also feature operable office windows that employees can open and close as needed. On the main guest floor, an automated ventilation system takes advantage of the natural air currents of Golden Gate Park to regulate the temperature of the building. Throughout the day and night, louvers will open and close, providing fresh air and cooling the building thereby reducing the dependence on traditional HVAC systems and chemical coolants.
Skylights, providing natural light to the rainforest and aquarium, are designed to open and close automatically. As hot air rises throughout the day, the skylights will open to allow hot air out from the top of the Academy while louvers below draw in cool air to the lower floors without the need for huge fans or chemical coolants.
Radiant Floor Heating
Warm air rises. A traditional forced-air heating system for the 35-foot-high public spaces in the museum would be wasteful in the extreme. Instead, the Academy is installing a radiant heating system in the museum’s floors. Tubes embedded in the concrete floor will carry hot water that warms the floor. The proximity of the heat to the people who need it will reduce the building’s energy need by an estimated 10% annually.
Insulation also keeps buildings warm. The Academy, rather than using typical fiberglass or foam-based insulation, chose to use a type of thick cotton batting made from recycled blue jeans. This material provides an organic alternative to formaldehyde-laden insulation materials. Recycled denim insulation holds more heat and absorbs sound better than spun fiberglass insulation. It is also safer to handle. Even when denim insulation is treated with fire retardants and fungicides to prevent mildew, it is still easier to work with and doesn't require installers to wear protective clothing or respirators.
The Material World
- 90% of all demolition materials were recycled
- 32,000 tons of sand from foundation excavation applied to dune restoration projects in San Francisco
- 95% of all steel from recycled sources
- 15% fly ash (a recycled coal by-product), 35% slag in concrete
- 50% of lumber harvested from sustainable-yield forests
- 68% of insulation comes from recycled blue jeans
- 90% of office space will have natural light and ventilation
- 60,000 photovoltaic cells; 213,000 kilowatt-hours; 5% to 10% savings of electricity
- 30% less energy consumption than federal code requirement