Chicagoans who live at 900 North Michigan Avenue don't head to the country to commune with nature. They go to the 10th-floor roof.
A garden with 21,400 plants and grasses overlooking downtown lures residents such as Beth Kronfeld.
"There's a certain peace and serenity when you can see grasses blowing in the wind and noise from the traffic is a little dimmer,'' says Kronfeld, 29, who reads there on weekends.
Chicago has out-built larger cities New York and Los Angeles in green roofs. It took the lead in North America with 517,633 square feet (48,090 square meters) in 2007, industry group Green Roofs for Healthy Cities says. The city expects to have more than 4 million square feet of gardens on 400 buildings under construction or completed this year.
Mayor Richard Daley, inspired during a trip to Germany, led the city to mandate in 2004 that new buildings have green space and provide grants to spur developers to add roof vegetation. Proponents say plants in non-organic mix on a waterproof membrane reduce building temperatures, energy costs and runoff, making it worth paying as much as double the price of a typical roof.
"Chicago definitely stands out,'' says Eva Wong, a program manager for the U.S. Environmental Protection Agency's Urban Heat Island Program based in Washington. "They have a grant program that helps advance the mayor's green-roof agenda.''
Higher Costs
Green space among the clouds doesn't come cheap: Sky-high gardeners pay $13 to $30 per square foot more for trays that sit atop a standard roof, says Grace Rappe, an associate principal at Hoerr Schaudt Landscape Architects in Chicago, designer of the 900 North Michigan space.
High-end gardens that cost $30 a foot include more soil and plants than in the $13 version and the flora requires less maintenance, Rappe says.
Even fans of the roofs say buyers may not want to pay more. "When push came to shove, they wouldn't be willing to fork over $20,000 or $30,000,'' Kronfeld says.
Builders at 900 North Michigan never priced a roof without greenery, so the added cost that was incurred isn't available, says Jaimie Bulla, a manager for Development Management Associates LLC in Chicago.
The space features about 14,000 square feet of plants surrounding a 2,700-square-foot deck with grills, dining tables and chairs. The garden covers the top of the attached Four Seasons Hotel, though it's available only to 900 North Michigan residents.
Avoiding Weeds
A green roof may cut a building's cooling bills by 21 percent, according to a study released in July that was led by Mark Simmons, an ecologist at the University of Texas at Austin.
"Energy savings from a green roof will vary considerably and can be as low as 5 percent of the cooling costs or as high as 35 percent,'' said Steven Peck, president of Toronto-based Green Roofs for Healthy Cities.
Annual savings on projects have ranged from about $5,000 to $50,000, Peck said.
Chicago's roof initiative is one of Daley's environmental efforts that include cleaning up the Chicago River, adding small parks and converting a former downtown airport to open space.
The city's Green Roof Improvement Fund for the financial district offers matching grants of as much as 50 percent for the projects, with a limit of $100,000 for those done this year. Chicago offers $5,000 for all residential buildings and commercial sites no bigger than 10,000 square feet, says Michael Berkshire, a developer with the Chicago Department of Planning and Development.
Speeding Approvals
Developers can get projects approved faster with a green roof, reducing carrying costs, he says.
New York is also promoting the concept. A law signed in August offers one-year tax abatements for construction of green roofs in any city in the state with at least 1 million people. The legislation will create installer and planner jobs, says Assemblyman Ruben Diaz Jr., the author of the bill.
The industry for the roofs is growing in Germany, France, Austria and Switzerland, according to Green Roofs for Healthy Cities. They are growing in popularity because they save energy by providing insulation, says Jennifer Molloy, the green infrastructure coordinator for the EPA's Office of Water.
Chicago's first public green roof was built on the city hall in 2001. On the portion containing 20,300 square feet of plants, temperatures reached 119 degrees Fahrenheit (48 Celsius) in August, versus 169 degrees on the rest in traditional black tar.
Green roofs may also spruce up the view for neighboring tower dwellers.
"With all people living in high rises, roof-scapes are their landscapes,'' Berkshire says. ``Now they can look at rooftops covered in grass.''
