Our Rooftop

Photo: Tom Harris Photography

Photo: Tom Harris Photography

“Standard green roofs are used to reduce the heat island effect of cities, but what if we took this idea to an entirely new level? I’m imagining a new ecological network at the height of the rooftops—one that is defined by vivid, heterogeneous trees and plants that create habitat in the sky and amplify urban biodiversity on a regional, and ultimately global, scale.”

—Jeanne Gang, Preface to Island in the Sky

We established our rooftop prairie in 2015 in collaboration with Omni Ecosystems. Photo: Tom Harris Photography.

We established our rooftop prairie in 2015 in collaboration with Omni Ecosystems. Photo: Tom Harris Photography.

Photo: Tom Harris Photography.

Photo: Tom Harris Photography.

Supported by the robust structure of our 1938 art deco building, we’ve transformed the once-blank rooftop of our Chicago headquarters into a lush green space where nature, people, and city converge.

Outdoors, we’ve developed a 5,000-square-foot functioning prairie ecosystem where more than seventy plant species provide habitat and forage for insects and wildlife, including three colonies of honeybees. This unique green roof is a living laboratory where we’re working with ecologists and other specialists to build a body of knowledge—and eventually, best practices—about how urban rooftops can become an ecological network of green spaces that cultivate much-needed biodiversity. (Learn more in Island in the Sky, a field guide to our rooftop ecosystem.) Within the soft prairie landscape we’ve built a transparent “Treehouse” pavilion. This flexible indoor space hosts office gatherings, workshops, and yoga, as well as public events that invite the community into the Studio for discussions on design and related topics. 

Surrounded by the changing colors and textures of the prairie and the busy city beyond, it is easy to imagine a future in which natural and urban environments coexist and thrive.

Our rooftop prairie’s black maple, bur oak, and downy hawthorn trees require increased soil depth to allow for root growth. To accommodate the extra weight of the tree mounds, we planted them in line with the interior columns of the building. The weight of the trees and soil is carried efficiently by load paths straight down to the building’s foundation.

Our rooftop prairie’s black maple, bur oak, and downy hawthorn trees require increased soil depth to allow for root growth. To accommodate the extra weight of the tree mounds, we planted them in line with the interior columns of the building. The weight of the trees and soil is carried efficiently by load paths straight down to the building’s foundation.

In 2017 we introduced two colonies of honeybees on the rooftop, which have since grown to three. These important pollinators help our prairie plants thrive, and observing the dynamics of the hives indicates the health of our overall rooftop ecosystem. The hives are managed by the Chicago Honey Co-op.

In 2017 we introduced two colonies of honeybees on the rooftop, which have since grown to three. These important pollinators help our prairie plants thrive, and observing the dynamics of the hives indicates the health of our overall rooftop ecosystem. The hives are managed by the Chicago Honey Co-op.

To track the health, growth, and biodiversity of the rooftop ecosystem, we conduct annual bioblitzes led by ecologists Steve Apfelbaum and Susan Lehnhardt of Applied Ecological Services. During each bioblitz we use citizen science techniques to count and identify the plant and animal species found on the roof. We also collect soil samples that are analyzed in a laboratory to measure microbial life. Evaluated comprehensively, the bioblitz data demonstrates how we can best manage the rooftop prairie for optimal development and ecosystem services.

To track the health, growth, and biodiversity of the rooftop ecosystem, we conduct annual bioblitzes led by ecologists Steve Apfelbaum and Susan Lehnhardt of Applied Ecological Services. During each bioblitz we use citizen science techniques to count and identify the plant and animal species found on the roof. We also collect soil samples that are analyzed in a laboratory to measure microbial life. Evaluated comprehensively, the bioblitz data demonstrates how we can best manage the rooftop prairie for optimal development and ecosystem services.

Students from a neighboring elementary school joined us for the 2018 bioblitz.

Students from a neighboring elementary school joined us for the 2018 bioblitz.

The Treehouse space is also available for private event rentals. Visit Peerspace for more information.

The Treehouse space is also available for private event rentals. Visit Peerspace for more information.