The potential of local food, energy, and water production systems on urban rooftops considering consumption patterns and urban morphology

Abstract

The external resource dependency of urban areas results in the externalization of environmental and socioeconomic impacts. Implementing food, energy and water production systems on urban rooftops (roof mosaics) can potentially help cities become more self-sufficient but depends on the city's urban morphology. We studied the supply potential and impacts of four roof mosaic scenarios for different urban forms in Cerdanyola, a 58 thousand-inhabitant town in the metropolitan area of Barcelona. We combined spatial analysis of potential rooftops, metabolism analysis, and social and environmental impacts. The municipality has an average rooftop/household potential of 31 m2 on which to implement any of the mosaic scenarios, with the highest potential in the single-family housing typology. The highest level of vegetable self-sufficiency was found in housing estates (32%), and the lowest in originary fabrics (28%). Regarding electricity and water self-sufficiency, the highest self-sufficiency level was found in the single-family housing typology (51% and 14%, respectively) and the lowest in housing estates (26% and 8%, respectively). Regarding impacts, the implementation of the electricity and rainwater harvesting systems depicts the most positive indicators in single-family housing areas. However, for housing estates and originary fabrics typologies, the best performance is shown to be in the implementation of rooftop farming systems.