In the blue-collar birthplace of the skyscraper, a city of concrete and steel, a green movement is building upon, well, buildings.

Since 2005, Chicago has embarked upon an ambitious plan to turn the city’s barren rooftops into urban oases. Thanks in large part to Mayor Richard M. Daley’s incentive program offering $5,000 grants to residences and small businesses, as well as requirements that some large retailers install green roofs as part of doing business in the city, Chicago now has more living green roofs than any other city in the country, say authorities.

They cover about 2.5 million square feet of rooftop real estate, the equivalent of more than 60 acres.The world’s largest green roof, Millennium Park, which is built over train tracks and an underground parking garage, spans more 24.5 acres, half of it planted in grass, shrubs, trees, gardens, also is located in Chicago. The number of buildings in Chicago that have installed green roofs is approaching 300, according to city authorities. Nationally, installations of green roofs are growing 30 percent annually, according to the most recent survey by Green Roofs For Healthy Cities, a 10-year-old non-profit industry trade group based in Toronto. Roughly 2.5 square feet of new green roofs were installed in 2007, the latest year for accurate numbers.

Along with Chicago, the other top American cities for green roof installations in 2007 were Wilmington, Del. (195,600 square feet), Baltimore (121,550), Brooklyn, N.Y. (102,908), and Virginia Beach (100,500).

What city businesses and residents realize is that a bit of green can bring big benefits in insulation, fuel costs, air quality, storm water management, and even wildlife habitat. Not only is a green roof pretty to look at, it also provides crucial habitat for birds, bees and butterflies in downtown. It’s been estimated that 16 square feet of green roof provides enough oxygen for one person.

“It really helps mitigate the urban heat island effect,” said Margaret Collins, marketing coordinator for Tecta America Corp., one of the largest green roof installers in the U.S. “Your traditional dark black industrial roof can get up to 160 degrees on a hot summer day but green roofs stay at the ambient temperature because the plants absorb the light and the heat.“

Good Green-Collar Jobs

Tecta, headquartered in Skokie, Illinois, is the largest union roofing contractor in the United States. The company started in 2000 with about 1,000 employees in 10 locations around the country. Today, said Collins, Tecta employs more than 3,500 associated roofing professionals in 48 states.

Anthony Roofing, one of Tecta’s subsidiaries in Illinois, is installing a green roof for Chicago’s Midway Airport. The company’s roofers are represented by Local 11 of the United Union of Roofers, Waterproofers, and Allied Workers. The first large green roof built in Chicago is, appropriately enough, atop City Hall, where it has become a signature of Mayor Richard Daley’s strategy to build prosperity through new clean energy, efficiency, and environmental programs.

While the city is working with scientists from the U.S. EPA and Lawrence Berkeley National Laboratory to estimate the effects of gardens, such as the 20,000 square foot green roof on City Hall, a final analysis has not yet been completed. However, the city estimates that it is saving more than 9,000 kilowatt-hours of electricity a year.

While the economic benefits of green roofs may take some time to quantify, the aesthetics advantaged are instantaneous.

“It’s just so much nicer to step out and use a roof that has a garden on it,” said Collins.

Reprinted with permission from the Apollo Alliance. Cassandra Stern, a former reporter for The Washington Post, contributes to the Apollo Alliance. Keith Schneider, an environmental and energy journalist, is the communications director for the Apollo Alliance.