The Transformative Power of Large Scale Green Roof Projects

Sourced from the Living Architecture Monitor

Cites around the world are changing rapidly in response to population growth and the need to build for resiliency in the face of extreme weather. Now more than ever, government, planners, and architects recognize the need to have multifunctional spaces integrated into the urban fabric.   Rising land values make land used for utilities and transportation corridors more valuable than ever.  
    
Chicago was the first major city in North America to cover its rail yard and parking lots with a multifaceted roof park. Millennium Park is a 24.5-acre bustling green space in the city’s core built next to Grant Park. San Francisco, dubbed the greenest city in America is striving live up their name with the futuristic Transbay Terminal Centre set to be up and running early 2018, seven years after construction began in 2011. The City of Toronto, is currently exploring the possibility of covering its downtown rail corridor into a 21-acre roof park. 

This is a review of these three major projects which exemplify the global trend toward building green roofs on land and buildings as a key element in 21st Century city building.  

Chicago’s Millennium Park

Despite initial opposition and considerably cynicism about the project, Chicago’s award of excellence winning Millennium Park opened in July 2004 after starting construction in October 1998. The eyesore of the rail deck from the offices above is said to have inspired visionary mayor Richard M. Daley to cover the trail tracks with a park.  Since its opening in July 2004, Millennium Park has become Chicago’s top tourist destination with many outstanding and unanticipated benefits.  Major features of the roof park include the Jay Pritzker Pavillion which can accommodate 11,000 music lovers, Cloud Gate a 100 ton sculpture by Anish Kapoor, the interactive Crown Fountain by Jaume Plensa and the four season Lurie Garden, designed by Kathryn Gustafson, Piet Oudolf and Roberter Israel. These features all sit on atop a parking garage and a commuter rail station which services the downtown core of the city.  The project’s construction cost, worth more than $470 million, was financed through a combination of $270 million in public funding with the remaining secured through private donations. 
  
A study conducted by Dennis Jerke from Texas A&M University in 2011, found that of the 39.2 million domestic and overseas visitors in 2010, 12 per cent visited Millennium park and this accounted for $1.4 billion of direct spending and 78 million in tax revenue during that year alone.    In 2017, Millennium park was the top tourist destination in Chicago, and among the top ten destinations in the U.S.  The park hosts numerous festivals and events throughout the year, including the Grant Park Music festival.  Since the park opened, there has also been an increase in development around it, which has resulted in more than 4,800 apartment and condo units, all within walking distance of the park.  This real estate boom was stimulated in part, by the construction of the park. 

The environmental case for Millennium park is significant. The park retains almost 70 per cent of the stormwater that falls on the site and the remaining 30 per cent is cleaned, filtered, and diverted in the Chicago River.   The park more than 500 trees help remove 426.9 pounds of air pollutants each year.  This has an estimated to have a value of $1000/ year.  Millennium Park and the culture it has created around environmental stewardship no doubt have a role to play in Chicago’s ongoing this success in moving towards sustainability. In 2017, Mayor Rahm Emanuel announced that Chicago had met 40 percent of its Paris Climate Agreement commitments. The City reduced its carbon emissions by 11 percent from 2005 to 2015 while noting that jobs within the city increased 7 percent.  Chicago has long been a supporter of green roof development, through regulations and incentives and Millennium Park is an award winning example of how green spaces contribute to a both a city’s economy and ecological diversity.

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