Of the many museums in San Francisco, CA, the California Academy of Science stands out as more than just a museum. It is also a prime example of a green commercial facility. In fact, it is the world’s greenest museum and has a Platinum-level LEED certification. My husband and I had a chance to tour this building in early October and see, among the many exhibits, its very unique green roof.
On the surface, the green roof appears to be a simple grassy, meadow-like landscape, but under the surface, it’s much more complex. A visitor sign detailed the many layers of the green roof. The base is the concrete roof top, followed by thermal plastic waterproofing to keep water from leaking into the building. Then, there is a layer of insulation to prevent UV damage and heat loss, followed by another protective polymer layer. Next up is a drainage layer, a filter sheet, additional soil, and finally the surface layer - a biodegradable tray with plants and soil.
One unique thing about this particular green roof is its hills. It was designed by Architect Renzo Piano to mimic the landscape of San Francisco, famously known as the “City of Seven Hills.” Underneath the roof’s two largest hills is the rainforest and planetarium. Not only do these particular hills make for an artistic landscape, but they also release hot air from the building via round, porthole-like skylights. Speckled in the grassy landscape are other features including vents for the HVAC system and gabions - pathways that prevent erosion, carry excess water to an overflow reservoir, and serve as access for roof maintenance.
The benefits of the green roof are plentiful. Since the green roof is made of native plants, it attracts and feeds natural wildlife such as bumblebees, butterflies, and hummingbirds. It also absorbs rainwater which reduces flooding and pollution runoff in the wet city of San Francisco. In fact, it retains 98% of the rainfall, and just a small percentage is channeled to the ground below. It also serves as an outer insulate layer for the roof.
On the roof, you’ll notice another green feature - an awning of solar panels (photovoltaic cells). Per year, these sixty-thousand cells produce 213,000 kilowatt-hours of clean energy, which cover 10% of building’s energy needs. In addition, the directional location of these cells protects the building from the full sun and heat in the summer, but allows the sun and heat to enter in the winter months.
The California Academy of Science features other green building features including glass construction for natural lighting, an automated ventilation system that uses skylights and louvers for natural air flow, radiant floor heating, and denim insulation.
This state-of-the-art building serves as an model for other facilities to aspire to, and may soon become the norm. Why? Because facility owners are realizing that green buildings are more inexpensive to run, aesthetically pleasing, help enhance work productivity, conserve resources, and protect the health of employees and visitors.
All material for this article was sourced from visitor signs at the California Academy of Science and from their website, www.calacademy.org.