DeStefano + Partners, The Beitler Company, AMEC
Dearborn Center is a high-rise office building with an eight-story mid-rise “bustle” visible from the tower and surrounding high-rises. Site zoning for the site was a Planned Development (PD), due to its size. In the course of the PD review the Department of Planning and Development (DPD) requested that the developer install a green roof above the bustle; this was the first green roof required by DPD as part of the Planned Development process, although it is now a routine requirement.
The goals of the green roof were threefold: 1) mitigate the “urban heat island” effect by installing a roof that would not absorb light and convert it to heat, 2) provide additional stormwater detention capacity, which is important to Chicago’s overloaded combined sewer systems, especially in the densely developed Loop, and 3) provide an attractive roofscape for views from the surrounding high-rise buildings. Wolff Landscape Architecture, Inc. worked closely with the architect, DeStefano + Partners, to develop the green roof design and specification that would work within the constraints of the structural design, requirements for window washing, and other routine rooftop maintenance and access. The American Hydrotech green roof system was specified, and the landscape architect prepared the planting design consisting of not only the usual sedums and other drought-tolerant perennials, but also including more ornamental and garden-like perennials. These perennials were more drought-resistant native plants, and were specified at a larger size (one gallon containers) in order to provide greater visual impact at time of installation.
In addition to the anticipated benefits noted above, the Dearborn Center green roof has also turned out to provide unexpected wildlife habitat in the heart of Chicago’s Loop. A summer day finds barn swallows, goldfinches, and multiple species of sparrows flying over, perching, and feeding in the green roof, while crickets, grasshoppers, beetles, and other insects have also found suitable habitat. The project was completed in 2002.