CALIFORNIA ACADEMY OF SCIENCES GREENROOF

Where is The Greenest Museum in the World? In our own back yard.

The California Academy of Sciences is considered to be the greenest museum in the world with a Platinum LEED rating. The museum has the largest living roof in California, featuring seven dramatic hills designed to mimic the hills of San Francisco. This unique greenroof or living roof brings a positive influence to the Bay Area’s ecosystem, providing the beauty of self-sustaining local plant materials.

The roof is padded with six inches of soil keeping interior temperatures about 10 degrees cooler and decreasing the urban heat island effect, overall staying about 40 degrees cooler than a standard roof. Some of the slopes exceed 45 degrees, which is much steeper than any other living roof.

The living roof is composed of seven layers of material designed to:

Create insulation
Prevent runoff
Retain soil
Allow for drainage
Promote healthy plant growth

The seven layers, from top to bottom are:

Sustainable, biodegradable coconut husk trays developed using tree sap and coconut fiber, a waste product from coconut plants in the Philippines. The trays were filled with three inches of soil and native California plants. A total of 50,000 trays containing 1.7 million plants were placed on the roof by crane and installed like tiles. The plants are expected to grow from one tray into the next, locking them together into a tightly woven quilt of vegetation that will biodegrade over the next several years.
Three inches of additional soil totaling over 1,000 yards.
Erosion control blanket to retain soil on the slopes, moisture mid-slope, and control pests.
Drainage layer to prevent plants from rotting.
Insulation layer to stabilize internal building temperatures.
Waterproofing layer.
Concrete slab following the contours of the hills make up the balance of the greenroof.

There were nine species of plants installed in the baskets, some of the more familiar included: California Poppies, Lupine, Goldfield and Sedum.

A few other little known facts are that the roof totals 197,000 square feet and the cost was approximately $17 per sq. ft. There are 4.5 acres of total roof space that includes a solar panel canopy for generating energy and 2.5 planted acres.

And, it took Jensen Corporation only four months to install!

Here are some additional greenroof/living roof facts:

There are significant savings on heating and cooling costs, often up to 25%; as well as substantial sound insulation from the soil, plants and trapped layer of air.
Improved air quality occurs from the greenroof filtering the air moving across itself and can remove up to 4.4 lbs of airborne particulates from the air every year.
Temperature reguation occurs through a daily dew and evaporation cycle; plants on vertical and horizontal surfaces can cool cities during hot summer months. In the process of evapo-transpiration, plants use heat energy from their surroundings when evaporating water. Reduction of the 'Urban Heat Island Effect’ also reduces production of smog and can help reduce greenhouse gas emissions.
Storm water retention can be stored by the substrate and then taken up by the plants, it is returned to the atmosphere through evapo-transpiration. In summer, greenroofs can retain 70-90% of precipitation falling on them; in winter they retain between 25-40%. In addition to water retention is water filtration, greenroofs not only retain rainwater, but also moderate the temperature of the water and act as natural filtration for any water run off

Greenroofs can facilitate a significant improvement in the LEEDtm rating of a building, contributing as many as 15 credits under the current rating system.

Construction of Roof Layers

Jensen is an employee-owned landscape company comprised of Jensen Corporate Holdings with four subsidiaries: Jensen Corporation Landscape Contractors, Jensen Landscape Services, Jensen Landscape and Construction Company and Huppe Landscape Company. For more information on greenroofs or to speak to someone regarding landscaping, please contact Jensen.

Phone: 408-446-.4555; www.jensencorp.com

Article provided by: Nancy Schafer, Jensen Landscape Services