[Sdpg] Garden in the Sky (from Utne.com),

[sdpg-admin at arashi.com]

Hi everyone
	Here is a amazing change that is happening in Europe and spreading to US, 
could we imagine one step further add to the design of roof gardens , fruit 
bearing trees with a perennial food forest underneath, vines and more, just 
a beginning so that we have added more functions of design, what we call in 
Permaculture Stacking
				wes
	

Hi! Check out this article on Utne Reader Online.
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"Garden in the Sky - In Chicago and elsewhere, rooftops are coming alive 
with greenery"
By Claudia Lenart, Conscious Choice
http://www.utne.com/bNewPlanet.tmpl?command=search&db=dArticle.db&eqheadlinedata=garden%20in%20the%20sky

In Chicago and elsewhere, rooftops are coming alive with greenery

By Claudia Lenart, Conscious Choice

Gardeners and environmentalists in Chicago are moving into uncharted 
territory in their effort to moderate summertime heat: up on the roof. 
Rooftop gardens are sprouting on buildings throughout the city, redefining 
urban green space in the process. Chicago is only one of many places trying 
to capitalize on the fact that plants are natural air conditioners. 
Meanwhile, city dwellers are discovering that flowers, grasses, and trees 
also make great upstairs neighbors.

</graphics/cafelogo.gif> Discuss rooftop gardening at the Nature conference 
in Café Utne's: cafe.utne.com

"Rooftop gardening is going to become more popular as land becomes more 
precious," says Liz Serritella, co-owner of Chicago’s Old Town Bed & 
Breakfast and a new rooftop gardener. "I love to dig in the dirt. We had 
gardens before, and when we moved I couldn’t garden anymore," says 
Serritella. Then she put in two rooftop gardens, to the delight of her guests.

Environmental designers would like to see the same thing happen on a much 
wider scale.

"Flying into O’Hare airport, you see acres and acres of bare roofs. They 
all could be green, and that could make an enormous difference," says David 
Yocca, principal of Conservation Design Forum, a design group of landscape 
architects, ecologists, and botanists. The firm has been greening up a 
large area on the 38,800-square-foot roof at Chicago’s City Hall, building 
a garden that as soon as this spring will harbor as many as 150 different 
plants. Their efforts are part of the U.S. Environmental Protection 
Agency’s Urban Heat Island Reduction Initiative, which aims to reduce smog 
by lowering the temperature in five congested cities.
Like dark clothes, dark rooftops absorb the sun’s rays, heating city 
buildings and streets by as much as eight degrees. Hotter buildings need 
more air-conditioning, which leads to higher energy use and more 
fossil-fuel pollution. The heat also cooks the pollution, creating 
ozone-heavy smog. Other cities in the urban heat island project—Baton 
Rouge, Houston, Sacramento, and Salt Lake City—plan to use reflective roof 
surfaces to control the heat-island effect. Chicago is the only city 
testing whether green rooftops can accomplish the same thing.

Plants cool the air by releasing water vapors through their leaves, a 
process called evapotranspiration. According to computer models conducted 
by the Lawrence Berkeley National Lab, which is participating in the heat 
island project, widespread use of reflective surfaces and green roofs could 
reduce summer temperatures in cities by several degrees.

Rooftop gardens aren’t new; historical accounts date back 2,500 years to 
the Hanging Gardens of Babylon. During the Renaissance, Pope Pius II had a 
roof garden built at his summer residence in Pienza, Italy. More recently, 
settlers on the American plains built sod houses to insulate themselves 
from extreme cold as well as heat.

Green roofs are starting to catch on across the United States, says Matt 
Carr, Garden Roof product manager for American Hydrotech, a company that 
manufactures roofing membranes, including the one used on Chicago’s City 
Hall. Three years ago, says Carr, "we were working with two or three green 
roof jobs. Today, we’re overseeing about a hundred green roofs throughout 
the States."

The potential benefits of green roofs are nearly as varied as the plants 
that can grow on them. In Portland, Oregon, where the challenge is not heat 
but rain, builders are encouraged to use green roofs as a possible way to 
win the city’s ongoing battle with stormwater runoff. The celebrated 
eco-friendly Gap headquarters in San Bruno, California, also features 
green-roof architecture.

In Europe, green roofs are catching on even faster. According to Theodore 
Osmundson, a landscape architect and author of Roof Gardens: History, 
Design and Construction,  43 percent of German cities offer financial 
incentives for building green roofs. But that’s not surprising: Many of the 
drainage and barrier technologies that have made green roofs a realistic 
solution for today’s structures were developed in Germany. European rooftop 
gardens function not only as runoff control systems, but as small parks, 
complete with ponds and, in one case, even with a miniature golf course.

A green roof consists of several layers. At Chicago’s City Hall, the roof 
was covered with a seamless membrane made of hot, rubberized asphalt 
designed to last as long as the building. Above that sits a synthetic mat 
that creates a grid-like canal system between the barrier membrane and the 
overlying gravel and soil. Though more than half of a typical rainfall will 
be caught in the gravel and soil, a layer that ranges from 3 to 30 inches 
thick, the remaining water can thus drain off without it drowning the 
garden—or dripping into the offices below.

When the City Hall garden is complete, it will contain 20,000 plants, from 
shallow-rooted sedums and ivies to shrubs, hawthorn, and crabapple trees. 
Many of the plant species will be of native origin because they are hardier 
and can withstand drought and high winds. Most native prairie plants have 
root systems that are too deep for roof gardens, but species that are found 
in hilltop prairies have shallower root systems, green roof designer David 
Yocca says. Ground-cover plants, including sedums, mosses, and grasses, can 
tolerate both too much and too little water. These plants will go dormant 
and turn brown during a prolonged drought, then green up again as soon as 
it rains, Yocca adds.

The City Hall’s roof is not open to the public, but it can be seen from a 
number of nearby buildings. Local scientists will monitor a green garden’s 
effect on climate, with the help of infrared satellite photos that register 
heat levels. The roof’s insulating capacity is expected to save the city 
$4,000 a year in cooling and heating bills. In addition, the soil and plant 
cover protect the roof from the elements, which should extend its life and 
make it easier to maintain. "Green roofs can last 50 to 100 years as 
opposed to a 15-year roof," says Yocca.

A green roof on top of City Hall is only part of the solution, of course. 
The city intends to install green roofs (and solar panels) on other public 
and private buildings. But their impact on summer swelter will be limited 
until private building owners follow the city’s example. Simpler versions 
requiring only a few inches of sod planted with low-growing plants are 
relatively inexpensive, and city officials hope their efforts will start a 
trend.

-- Claudia Lenart
 From Conscious Choice

 From Conscious Choice (July 2000). Subscriptions: $24/yr. (12 issues) from 
920 N. Franklin, Suite 202, Chicago, IL 60610.

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