The captivating panorama from the Empire State Building in Manhattan is well-known to many. Skyscrapers extend as far as the eye can see, the Hudson River blends into the distant horizon, and a diminutive copper-clad lady, standing at a height of 46 meters, symbolizes freedom. However, the allure of the far-reaching view eventually fades, leading the gaze to return to seemingly insignificant details below. Yellow taxis, meandering paths of individuals, sudden flocks of pigeons taking flight, and the intricate patchwork quilt of flat roofs—characteristic of major American cities—all capture the observer's attention. In contrast to Central Europe, where rooftop gardens are prevalent, these small rectangular spaces in the USA are primarily occupied by air-conditioning units, fresh water tanks, and occasionally, miscellaneous items. The absence of rooftop gardens highlights that the United States is still in the process of embracing this concept, showcasing its status as a developing country in the realm of rooftop greenery.
Atelier Dreiseitl
Landscape Architecture, Open Space Design, Stormwater Management, Rooftop Gardens and Urban Parks
This project was originally produced by Atelier Dreiseitl under the leadership of Herbert Dreiseitl. Since its merger in the year 2013 with the Ramboll Group A/S this project and the copyright is owned by Ramboll.
Location
Chicago, USA
Client
City Of Chicago, Dept Of Environment
Timeline
2000
Area
3.600m²
Status
Completed
The perspective from the Sears Tower in Chicago, one of the tallest office buildings globally, is less familiar to many. However, gazing downward from this height reveals a scenery reminiscent of Manhattan's rooftops. This may soon change, as Chicago, situated on Lake Michigan, is among the five major American cities participating in the 'Urban Heat Island Initiative' pilot project led by the environmental authority. This initiative is the United States' effort to mitigate high temperatures and smog levels during the summer months in various cities. A pivotal component of this program is rooftop planting, aimed at not only reducing temperatures but also alleviating strain on overwhelmed sewers during periods of heavy rainfall.
The green roof of the city hall has garnered significant attention, captivating specialists not only within Chicago but also beyond, as part of the environmental authority's pilot project. Within the city, it contributes to the comprehensive 'City Roof Garden Program,' serving as a pioneering example that underscores the value of rooftop planting, both economically and in terms of sustainable water management.
The scarcity of experts in roof planting in the USA, attributed to a lack of experience, prompted the inclusion of the Dreiseitl studio in an American planning team in 1999. They were tasked with creating a design for a roof space spanning approximately 3,600 square meters. Consequently, observers now peer down from the summits of adjacent skyscrapers onto the roof of the 11-story town hall. The walls beneath it boast a history of over a century and may be recognized by European film enthusiasts as the site where the infamous Blues Brothers settled their debts at the eleventh hour.
Atop the town hall, a gently contoured landscape has taken shape, featuring a shallow substrate adorned with various sedum varieties and a deeper one hosting trees and shrubs. A meandering path allows pedestrians to explore the city hall roof. Before the planting, sections of the roof were removed for structural reasons, and the provision of water for the rooftop plants was integrated into this process. Rainwater from the penthouse, housing technical units directly attached to the city hall and situated at a higher elevation, is collected in several small tanks and supplied to the plants as needed. In cases of water scarcity, the municipal supply can serve as an alternative source.
Enhancing the urban climate, the implementation of green roof surfaces plays a crucial role in substantially mitigating rainwater runoff. This is achieved through the processes of detention, storage, and evaporation, effectively managing and reducing the impact of rainfall in urban areas.
