Calif. Academy of Sciences green roof, San Francisco
As we celebrate Earth Day in an era when human population and cities are burgeoning, it is inspiring to see the growing utilization of green roofs.
A few of the environmental virtues of green roofs:
- Reduce building heating and cooling, stormwater run off
- Create native plantings and provide natural habitat for wildlife
- Filter pollutants out of air and rainwater
- Lower urban air temperatures
- Transform carbon dioxide into oxygen
Click here for more info.
Toronto, Canada; Mtn Equip Co-op Store (MEC) roof. Courtesy Wikipedia.
Defined as a building roof partially or completely covered with vegetation and a growing medium, green roofs have become a new trend in the 21st century…but they are not new.
Until the late 1800s, sod roofs were the most common roof on Scandinavian log houses. Sod roofs, made with birch bark, kept the house insulated from cold and moisture.
Osterdalen farmstead, Norsk Folkemuseum, Oslo, Norway. Courtesy Wikipedia
More here about the old sod roofs.
Eventually sod roofs fell out of vogue, but were revived in the 1960s in Germany. Today Germany has the most green roofs in the world; where they are part of the landscaping apprentice education.
Calif. Acad. of Sciences, SF. Courtesy Wikipedia.
San Francisco’s natural history museum, The California Academy of Sciences, was completely renovated in 2008 due to earthquake damage. This gave them an opportunity for new environmental upgrades, including a green roof.
SF Academy of Science. Green roof, “rolling hills” in center.
In the center of this large city, the roof provides 2.5 acres (1 h) of rolling hills and fields. A living science exhibit, the roof is open to museum viewers.
I visited there recently and not only was there a terrific view of Golden Gate Park, but white-crowned sparrows serenaded and butterflies fluttered past me.
The Academy reports 30-35% less energy consumption than required. More Calif. Academy Living Roof info here.
Green roofs vary depending on the depth of the planting medium. The deeper the layer of earth, the more installation and maintenance is required. A waterproof membrane and root barrier are always involved.
Rooftop container gardens, though beautiful, are technically not green roofs.
Learning how to maximize our urban centers into earth-friendly expanses will go a long way toward supporting and enhancing our growing population.
Photo credit: Athena Alexander unless otherwise noted
Chicago City Hall. So many abundant flowering plants here, beekeepers harvest 200 lbs of honey/year. Courtesy Wikipedia