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Originally a frontier outpost, Chicago, IL, has been a major railroad yard, a packing center, a town of labor unrest, a gangsters' den, a town of political unrest, and a sports fanatic's dream home.

So, the rough and tumble town's latest claim to fame may come as a surprise.

The Windy City is the nation's leader in green that can't be seen from street level.

Green roofs.

No, not roofs made of renewable materials. Not light colored reflective roofs. Not roofs adorned with solar panels.

Really leafy green roofs. Roofs that push up daisies, pansies and other delicate blooms. Trees above the eaves. Landscaping around the HVAC installation.

Rooftop gardening.

Industry group Green Roofs For Healthy Cities (GRHC) says, with nearly 300,000 square feet of rooftops cultivated in 2005, up from 200,000 square feet in 2004, ChiTown's total 2.5 million square feet of stuff growing on more than 200 rooftops throughout the City, makes the city top dog in verdant rooftops.

New York City, Washington D.C., Boston, Baltimore, and Ontario across the border, are other towns that boast of substantial rooftop gardening acreage, but Second City plans on remaining first in manicured landscapes that dot the skyline.

This summer, the city bankrolled a half million dollar Green Roof Improvement Fund that authorizes the Department of Planning and Development to offers awards of up to $100,000 to building owners who till soil on flat tops.

Green roofing isn't your typical in-the-ground garden. It's a "contained" green space on top of and unique to the individual roof.

GRHC, says the green roof system is an extension of the existing roof and includes water proofing, root repellent systems, special drainage and filtering systems, lightweight growing medium and, of course, the foliage.

For Chicago and other urban centers, it's not really about being at the top of the peat heap.

Rooftop gardening, once largely the realm of potted plants in urban areas where the asphalt is too ubiquitous and inhospitable to street-level gardening, has become a major weapon in the war against the urban heat island effect.

Go ahead global warming disbelievers. Roll your eyes, but it's scientific fact.

Bring organic materials back to the city and with them come benefits that serve the planet well.

GRHC says replace trees with structures with flat, black roofs, concrete and steel and you also replace vegetation's natural cooling properties with materials that absorb and then radiate heat long after the sun sets.

The urban heat island effect, the temperature difference between a city and its surrounding countryside, contributes to the greenhouse effect, which heats up the atmosphere and contributes to global warming.

Reduce the effect, say by swapping out flat roofs with gardens of vegetation, and urban areas can better cope with the warmer summers -- like the one gripping the nation this year.

But there are many more benefits, says GRHC.

  • A simple putting green or lawn can reduce cooling needs by 25 percent, reduce heat gain by 95 percent and heat losses by 26 percent. That means HVAC equipment size and insulation can be reduced at a cost savings.
  • Soil, plants and the trapped layer of air can absorb, reflect or deflect city sounds -- ground and air traffic, machinery, etc.
  • A rooftop garden is a lot more aesthetically appealing than an expanse of HVAC's humming away and it can make for unique meeting and recreation spaces. The birds and the bees are pretty happy about them, too.
  • You can grow food. The Fairmount Waterfront Hotel in Vancouver uses a rooftop garden to grow herbs, flowers, and vegetables on an accessible garden that saves its kitchen an estimated $30,000 a year in food costs.

Germany, where Chicago borrowed the idea, has greened 20 percent of all its flat roofs, which can vary from simple tray gardens to exotic systems like the 150 plant, apiary and two trees that adorn Chicago's city hall.

Zoning and building code issues currently makes it difficult to install a garden on most residential rooftops. The roof slope, load capacity, existing materials, drainage, waterproofing, electrical supply and other matters may be more difficult to overcome a home than at work.

The cost, about $10 to $24 per square foot could also be a factor, GRHC says.

A professional landscape architect and/or a roofing contractor, experienced in both roof top gardening and your area's building codes and zoning requirements, are virtually mandatory.

Explore Green Roofs For Healthy Cities' (GRHC) website for more information, frequently asked questions, how-tos, referrals, and more related information than you can shake a rake at.

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