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Construction began on the California Academy of Sciences green building in Golden Gate State Park in San Francisco on September 12, 2005. The design architect for the museum replacement project was Renzo Piano. The green building includes a remarkable array of environmentally friendly features that include: Produces 50 percent less wastewater than previously; Recycles rainwater for irrigation; Uses 60,000 photovoltaic cells; Supports a green roof with an area of 2.5 acres (1.0 ha); Uses natural lighting in 90 percent of occupied spaces; Was constructed of more than 20,000 cubic yards (15,000 m3) of recycled concrete; Construction includes 11 million pounds (5,000 t) of recycled steel; Wall insulation is made from scraps of recycled denim. The design was given the Urban Land Institute's (ULI) Award for Excellence:The Americas in 2008, considered the land use industry’s most prestigious recognition program, and won the Holcim Award Silver for sustainable construction projects for region North America in 2005. One critic praised the building as a "blazingly uncynical embrace of the Enlightenment values of truth and reason" and a "comforting reminder of the civilizing function of great art in a barbaric age." The new green building is at the forefront of environmentally-friendly design, in keeping with the Academy's focus on ecological concerns and environmental sustainability. It received Platinum certification under the LEED program. As a result of its environmentally-friendly design and other unique features, this project was featured on the Discovery Channel's Extreme Engineering series in 2006 and on the National Geographic Channel's Man-Made series in July 2008.
Soil as Insulation
Architect Renzo Piano achieved innovative, imaginative energy savings 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 six inches of soil substrate on the roof act as natural insulation, and every year will keep approximately 3.6 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.
Assembling a 197,000-square-foot rooftop to accommodate a living tapestry of native plant species is challenging enough. Add to that the technical problems posed by the roof's extreme dips and slopes. How to keep the plants and soil from sliding off? Rana Creek, who worked with Piano to design the roof, developed and patented a solution called the BioTray®. They used 50,000 porous, biodegradable trays made from tree sap and coconut husks as containers for the vegetation. These trays line the rooftop like tile, yet enable the roots to grow and interlock, binding the trays together like patchwork.
An open-air observation terrace enables visitors to get a close-up look at the roof's lush canopy of plants. The view encompasses the densest concentration of native wildflowers in San Francisco. The expansive vista is also an ideal location for watching Northern California’s birds, butterflies and insects. Skylights above the larger domes open and close throughout the day, enabling sunlight to reach the exhibits below. The steep slopes of the rooftop's hills draw cool air into the open piazza at the center of the building. Weather stations on the roof monitor wind, rain, and changes in temperature to help inform the automated passive ventilation systems.
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
• 30% less energy consumption than federal code requirement