FEATURE: Up On a Roof
Green roofs - they're as primitive and as old as early human habitations, and as futuristic and new-age as the 2008 Olympic city in Beijing. They have been in use in Europe for thirty years, and are fast gaining wide usage in the USA.
Green roof systems are ancient technologies that are once again being considered for a variety of modern applications. Their history dates back thousands of years. The most famous green roofs were the Hanging Gardens of Babylon, considered one of the Seven Wonders of the World. These terraced structures, constructed around 500 B.C. were built over arched stone beams and waterproofed with layers of reeds and thick tar. Soil, plants and trees were then planted. A version of green roofs were used in Iceland and other Nordic countries; the sod roofs used by pioneers on the American prairies were green roofs.
I've been researching this architectural feature for a couple of months now. The more I learn about it, the more I love it. We are planning a move to the Southwest of the USA in about a year. Doing this will entail downsizing our lives to fit into a much smaller house, hopefully of Pueblo design with a flat roof. That flat roof is where I hope to put my research on green roofs into actuality.
Most of the green roofs in the US are large public buildings. Chicago City Hall has one, so does the Toronto City Hall. Perhaps the best known is the roof of Ford's Rouge Centre Plant in Dearborn, Michigan. It covers 454,000 sq. feet and is the showpiece of Ford's effort to revitalize the historic plant. The Chicago roof is one of my favorites, because they are attempting - with a great deal of success - to establish a native prairie on this roof.
GREEN ROOF SYSTEMS
There are two types of green roofing systems, Intensive and Extensive. The extensive systems are for large expanses of rooftop not intended for public access. They use a scant amount of dirt, and mostly use sedums as their plant material. Intensive systems use a good deal more soil, and can support larger plantings, even trees.
Both of these systems have enormous beneficial possibilities for urban environments. Some of these are viable storm water management, energy efficiency, urban ecology and aesthetic benefits. Further benefits include insulating buildings, extending the life of the roof membrane, increasing property values, eliminating "heat islands," and providing wildlife habitat.
I mentioned the 2008 Olympics to be held in Beijing - well, the guy in charge of getting the city ready for this enormous undertaking, one Mr. Wang, has a masterplan to bring the city's air quality into line with the Committee's requirements that involves covering most of the rooftops of the city with green. See Mr. Wang's 'Garden in the Sky' for more info.
Landscape architects are getting very interested in this idea, as it opens up a whole new area to exercise their craft. However, so little has yet been written that there is a paucity of sources. The books I found on the subject are Green Roofs: Ecological Design and Construction and Planting Green Roofs and Living Walls. These two explain the history of green roofs, describe components and plantings used, and show off case studies from around the world. The third one is Cradle to Cradle: Remaking the Way We Make Things a book by two green and extremely inventive designers.
I'll close with some links to sites to see, learn, read more about green roofs. The best article I encountered is this one: Green Roof Activism, or, We are All Bozos on This Bus by Patrick Carey. It's full of information of all sorts, including places to find more information.
Green Roofs for Healthy Cities
Ford Dearborn Truck Assembly Plant
Green Roof Proposal, Temple University
"How Green is Your Roof?" Natural Life Magazine
Chicago City Hall
Greenroof Industry Resource Portal
Greenroofs, by Kathie Bond Borie
UPDATE: Check out this great Green Roof post on Treehugger.
UPDATE TO THE UPDATE: Just wanted to mention (especially to all those coming to this article via Treehugger) that it was written by a good friend and City Hippy collective member, Marigolds2, who normally writes for THE BLUE VOICE blog. They deserve a visit!