Hamburg, Germany Bunker to Convert Roof to Greenspace

Image courtesy of hilldegarden.org

Image courtesy of hilldegarden.org

An exciting project in Hamburg, Germany is slated to provide much-needed greenspace and stormwater drainage for the city later this year, converting nearly 60,000 square feet of roof into greenspace. The Hilldegarden project will completely remodel a former bunker in the St. Pauli neighborhood of Hamburg, creating an event space with a capacity of 1000 seats along with artist hotels, studios, and rehearsal spaces for musicians. The event space will be available for musical performances, film screenings, plays, district meetings, and a variety of other uses. Of the 8000 square meters of public space created by the Hilldegarden project, 5500 square meters will be dedicated to a park and garden area on the roof of the bunker. In addition to the rooftop park, plans include a ramp which will be planted with greenery and wrap around the building, allowing visitors to reach street level without going inside the building. The greenroof will provide relief for the stormwater drainage system in Hamburg, which has been under stress after recent flooding.

Image courtesy of hilldegarden.org

Image courtesy of hilldegarden.org

Hilldegarden will serve as a flagship project for the city, and will hopefully inspire other building owners in Hamburg to construct greenroofs as well. Under the leadership of Hanna Bornholdt, a municipal park will be built on top of an old bunker in the St. Pauli neighborhood, providing breathtaking views from the 40 meter high building. Construction is expected to start this year. As of now, only 0.8% of Hamburg’s rooftops are greenroofs. Given that modern greenroofs can absorb up to 60% of rainfall, Hamburg could certainly use more of them. Recent estimations state that Hamburg would need to spend billions of Euros to rebuild their drainage system to cope with flooding, which has been more recurrent in recent years. At the beginning of May, entire streets were flooded because the drainage system was unable to process precipitation from Hurricane Zoran. An increase in greenroofs could provide relief to the city’s drainage system, saving billions of Euros. Greenroofs could also alleviate the “heat pockets” – densely-developed areas where concrete and asphalt heat the city up like a stove – in the city, by absorbing heat and providing cool spaces for residents to relax.

Photo courtesy of miniatur-wunderland.com

Photo courtesy of miniatur-wunderland.com

Over the past few decades, local governments in Germany have encouraged residents to build greenroofs through tax breaks and financial incentives. Since greenroofs help absorb rainwater, those tax breaks are often applied to stormwater drainage taxes. As a result, the city of Düsseldorf has more than 730,000 square meters of green roofs – that’s the equivalent of 100 American football fields. In the 1980s and 1990s, Berlin offered a total of 16.5 million Euros in financial assistance for the creation of greenroofs and greenspaces – the city now has over 65,750 square meters of greenroofs as a result of this program. Some cities go so far as to require the construction of greenroofs. The city of Stuttgart requires that all new building roofs with a slope of less than 12 degrees have greenroofs. The city covers 50% of installation costs for the installation of greenroofs, at a maximum of 17.9 Euros per square meter. Munich requires that all buildings with flat roofs larger than 100 square meters must use part of that space for other purposes, and provides tax breaks for owners of buildings with greenroofs.

As the city of Hamburg continues to develop rapidly, public recreational spaces are becoming increasingly more crowded. Gaps between buildings are becoming a rarity, and the fields that used to exist throughout the city have given way to new buildings. Even existing municipal parks have been reduced in size to make room for construction. With incentives for building owners and Hilldegarden for inspiration, this could be Hamburg’s chance to catch up with other German cities and increase its greenroof acreage. I’m hopeful that with the help of innovators like Oisín Clancy and his company, Smart Roof, these types of greenroofs will help New Yorkers live more sustainably in the city within a few decades.

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