Friday, July 6, 2012

It’s Official: Chicago Boasts World’s Largest Green Roof!

Next week’s issue of Engineering News Record will officially recognize Chicago’s lakefront crown jewel – Millennium Park – as by far the world’s largest green roof. The park’s green roof area of 99,127 square meters dwarfs by far the second place contender – Frankfurt International Airport, in Germany – which at 80,000 square meters is really an aggregation of several smaller terminal buildings.

Millennium Park has several features beyond size to distinguish it from the other green roof projects honored in the ENR July 9 issue. It isn’t just a roof – it provides chair and lawn seating for 11,000 concertgoers who listen to the Grant Park Symphony and other groups performing in the Frank Gehry ornamented Pritzker Pavilion’s outdoor concerts all summer long. The roof includes 2.5 acres of native Illinois plants in the Lurie memorial garden. There’s a mirror surfaced bean shaped sculpture named “Cloudgate” by Anish Kapoor reflecting the skyline and street wall along Chicago’s famed Michigan Avenue, and a delightfully fanciful Crown family memorial fountain featuring the faces of animated anonymous Chicagoans spitting cool water for children and adults to splash in when the weather reaches this week’s hundred degree highs.

The park was the brainchild of former Mayor Richard M. Daley, who managed to put together a coalition of generous corporate and very well heeled private donors to fund about half its total cost, which ran around half a billion dollars by the time the park roof was completed. One of the first public/private partnership construction projects in the city, ultimately completed by Chicago based general contractor Walsh Construction, the donors of the rooftop enhancements formed a tax exempt organization to contract for and pay for their part of the job, then made a tax deductible gift to the City of both the funds to pay for construction of their enhancements and their contracts with Walsh to build them.

Fieldwork by the tradesmen who put up the Crown Fountain’s Jaume Plensa designed twin 50 foot high glass block towers housing the multiple projectors which create the “spitting images” of Chicago citizens, those who assembled the Kapoor Cloudgate sculpture and then polished it to a mirror finish, and those who erected the intricate free form aluminum Frank Gehry panels adorning the Pritzker Pavilion was so highly skilled and unique to the trades involved that Walsh Construction published a coffee table picture book of progress photos from the project heralding the dedication of these tradespeople. The title of that book, handed out to folks involved in building and paying for the project: “Better Than Perfect.”

According to the forthcoming article in ENR, green roof construction in the U. S. and Canada grew 115% between 2010 and 2011. American Society of Landscape Architects Executive Vice President Nancy Somerville touts the economic incentives for green roofs: “Green roofs have a higher cost up front, but the payback over time is significant,” she says, “not just in energy savings. It’s protecting your roof membrane – you can skip one or two or three roof replacement cycles.”

None of the big green roofs presently under construction around the nation and the world even comes close to the size of Millennium Park, and even if a bigger one were to be erected, it is quite doubtful any green roof built in the foreseeable future could ever rival Chicago’s crown jewel in accessibility to the public, scenic grace, or entertainment value. Chicago’s visionary politicians, business people and philanthropists who contributed their money and their genius to design and creation of Millennium Park have undoubtedly left their city a legacy which will stand the test of time.

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