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According to Inhabitat.com, the structure, designed for multi-use the structure is:
"...adjacent to the Hofgarten, Düsseldorf’s central park, the Kö-Bogen will help create a larger and more continuous open green space that runs from the city center out to the park and the Rhine. The green roof will help connect the building with the beautiful historical parks surrounding the downtown area, while reducing rainwater runoff and helping to significantly reduce heating and cooling costs."
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While a green roof is a significant element of sustainable design