A debate is blossoming at the California Academy of Sciences about whether sustainability is always the color green.
The living roof planted on top of the Academy has garnered national attention for being the cap on one of the greenest museums in the world. But in order to keep the 1.7 million plants in the roof garden sprightly year-round, the Academy has to turn on the sprinklers every now and then.
The 7-month-old roof and cannot survive without a little watering while the various species take root in an unusually thin layer of soil, Academy Communications Director Stephanie Stone said. The roof garden’s plants need another two years before they are robust enough to survive without being watered, she said.
“One thing that the Academy is aware of is that this is a learning tool,” Stone said. “Certainly there is an element there of wanting to make the roof attractive.”
Yet, some say the roof should be left alone to cycle through the seasons — it should be treated like an experiment in sustainable ecology, the argument goes. Others say that experiment could kill the plants before they have a chance to become established.
Ruth Gravanis, vice president of The City’s Environment Commission, recently suggested the Academy eventually stop watering the roof, providing visitors a lesson about the natural course of plant life.
“I would very much like people to be able to see how our natural flora changes with the seasons,” Gravanis said. “During summertime, plants rest, they go to seed. Things look different.”
Stuck in the middle is ecologist Paul Kephart, who designed the living roof. He would like to see the Academy experiment more with the watering patterns and schedules, but said the living roof is going to need artificial irrigation until it takes root.
“It’s a marvelous example of what we do know and what we don’t know about sustainable architecture,” Kephart said.
The green roof and Academy building have won accolades, but they are not even as green now as they could be since it uses fresh water — the same stuff we drink — instead of reclaimed water.
Right now, the water that sustains the roof garden is supplied from the Hetch Hetchy water system through low-flow irrigation.
A project that would bring reclaimed water to Golden Gate Park and the Academy has funding, but is still in the planning stages and will not be completed until 2013.
The winners are …
The roof top of the California Academy of Sciences is topped with 2.6 million pounds of soil and plants. Plant species were tested to ensure they can survive on the rolling hills of the roof with minimal irrigation. Some 30 species were tested on the roof of the old academy building. Nine finalists that made it to the new garden include:
1. Beach strawberries
2. Self heal
3. Sea pink
4. Stonecrop
5. Tidy tips
6. Miniature lupine
7. California poppies
8. California plantain
9. California goldfield plants
Source: California Academy of Sciences
