As part of an EPA study and initiative to combat the urban heat island effect and to improve urban air quality, Mayor Richard M. Daley and the City of Chicago began construction of a 38,800 square foot (total roof area) semi-extensive greenroof in April 2000. It was completed at the end of 2001 at a cost $2.5 million, funded by a settlement with ComEd. Encompassing one square block and twelve stories high, this retrofit application serves as a demonstration project and test greenroof. The project was completed in the summer of 2001 and will monitored for plant survival as well as other environmental features. Chicago City Hall’s greenroof saves $5,000 a year on utility bills, according to Michael Berkshire.
“This is unique to Chicago,” said Richard Price of the Virginia-based William McDonough & Partners, the architectural firm that is designing the garden. “No one else has looked at rooftop gardens to mitigate urban heat island effect, which is a process whereby highly urbanized areas with hard surfaces tend to be degrees hotter than green areas,” (ENN.com, May 2000).
According to a March 1, 2002 article in The Wall Street Journal, “The garden’s origins can be traced back ten years, to when the city’s electric utility, Commonwealth Edison, failed to make good on a 1991 franchise agreement. The city “sought legal recourse through binding arbitration and won a $1.1 billion settlement,” explains Jessica Rio, spokesperson for the Chicago Department of Environment (DOE). Some of that is being used to support Chicago mayor Richard Daley’s vow to make Chicago “the greenest city in America.”