Agriculture is an emerging urban use that can play an important role in providing food for increasing world populations, supporting circular economy and resilience, but competing with other uses for limited space. One option to address this spatial problem in relation to urban food production is to exploit rooftops.
For evaluation, the research team investigated the use, competition, and potential of urban roofscapes, using the city of Berlin as an example. An overview of current roofscape uses in Berlin is given, plans and initiatives for further expansion are presented, rooftop potential studies are compared, and important boundary conditions of rooftop uses are discussed. Berlin's roofscape of 97.3 km² (excluding 4.5 km² underground garages) already has a wide range of roof uses, with green roofs (11.8 km²) and solar roofs (0.7 km²) being the most common ones. As on the ground, commercial urban farming competes for space in the roofscape.
The study highlights rooftop aquaponics as a possibility to save resources by coupling fish and crop production and producing an animal protein with a low environmental footprint compared to other animal farming systems. Freestanding single-story aquaponic systems in inner cities should be avoided and in Berlin, approximately 800 buildings of appropriate using type exist with more than 2000 m² roof area as a precondition to host commercial rooftop aquaponics. The selection of specific sites should consider the availability of urban resources and requirements of an urban situation for the roofscape under existing as well as future competitive conditions. Further research efforts are required to adapt building regulations and planning laws, determine circular city locations for rooftop aquaponics, and evaluate the potential of peri-urban versus urban rooftop food production.
Read the complete research at www.researchgate.net.
Baganz, Gösta & Baganz, Elias & Baganz, Daniela & Kloas, Werner & Lohrberg, Frank. (2021). Urban Rooftop Uses: Competition and Potentials from the Perspective of Farming and Aquaponics -a Berlin Case Study.