Potential of urban rooftop farming in Berlin

Over time the human population has become increasingly urban. The proportion of city dwellers increased from 30% in 1950 to 66% in 2015. Due to this concentration of people in densely-built areas, a rethinking of agricultural and horticultural production is needed urgently. While the demand for fresh vegetables and other natural resources such as water and fuels increases the availability of the last two decreases ever-accelerating. Urban agriculture, defined as horticultural, agricultural or farming activities in and around urban centres, takes this development into account. Consequently, this work aims at identifying the possibilities of producing food inside the boundaries of a city with millions of inhabitants, nourishing them next-door. The present investigation has the objective to determine surfaces that could be used for rooftop farming in Berlin. As intensive crop production is intended, flat roofs of at least 1,000 m²/2,500 m² are chosen. Also the location as well as the function of the building itself and the surroundings play a role concerning symbiotic effects like usage of excess energy and waste water for plant production or additional benefit of insulation of the building. After identification of suitable rooftops for vegetable production, a potential production volume was calculated as well as the supply rate of vegetables of Berlin’s approximately 3.5 Mio inhabitants by means of rooftop farming. Out of a potential rooftop gross area of 925 ha a net acreage of 888.66 ha was calculated, deducting 4% for working tracks etc. The annual intake of Berlin’s inhabitants of the four main vegetables account for 87,300 t of tomatoes, 22,500 t of cucumbers, 24,000 t of lettuce and 10,000 t of bell pepper. Compared with the volume of the production of these species in high-tech greenhouses in Germany , the requested area for vegetable production was calculated for tomatoes, cucumbers, lettuce and bell pepper with 155.89 ha, 44.10 ha, 39.89 ha and 88.96 ha, respectively. This total of 328.84 ha leaves a spare area of 559.16 ha for vegetable cultivation on behalf of surrounding regions.