Investigating the 5th facades of cities: a parametric computational model of urban agriculture potentials

Abstract

The worlds population is becoming increasingly urban. By the year 2050, two-thirds of global population will live in cities (UN, 2014). Exploring holistic approaches to city design is crucial to manage tomorrows urban mutations. In fact, global sustainability depends on how urban systems will be managed in the 21st century (Ferrão & Fernández, 2013). A shift towards innovative planning solutions that are supportive of both social and environmental sustainability is imperative. Rooftop Agriculture (RA) could play a role in this transformation process. Rooftop gardens are multifunctional; hence provide several advantages such as enhancing biodiversity conservation, reducing flood risks or mitigating the urban heat island effect (Mentens et al., 2005). In many cities, due to urban pressure and land speculation, vacant space is rare. To solve this issue, numerous farm projects are growing on roofs, enabling efficient use of space in increasingly dense centers and converting unused surfaces into a more productive roof landscape. The projects take different forms and scales: from the self-built rooftop gardens such as the ØsterGro Farm in Copenhagen or the Gartenwerkstadt in Vienna, to the large rooftop soil farms in New York City with the Brooklyn Grange. Based on the Geographic Information Systems (GIS) data of the municipalities of Vienna and Rio de Janeiro City (RJC), the research objective is to conceive a set of parametric models which supports decision-making for implementing urban agriculture on the flat roofs landscape of cities. The targeted improvements are: the potential influence of rooftop gardens to enhance urban biodiversity conservation, the capacity to produce local food and consequently to provide food security, and the contribution to increase the city green cover. Through this investigation, the present thesis will answer the following question: how can parametric modelling methodologies contribute to the spatial analysis and detection of the key locations for rooftop agriculture within an existing urban landscape? 5 In Vienna, the municipality evaluated that 1068.4 ha, which represents 21% of the overall rooftop surface, would be suitable for intensive greening (Vali, 2011). Based on the inclination and the geometry of the roof landscape of Rio de Janeiro City (Light Detection And Ranging LIDAR data), the present research estimated that 1383 hectares of roofs would be suitable for RA on 69% of the city surface (without taking into account the structural conditions of the roofs). This productive roof area could produce enough food to meet the yearly demand for vegetables of 39.2% of the inhabitants. The study also demonstrated the great relevance of implementing RA in the poorest communities of RJC in the perspective of tackling food insecurity. After importing the GIS data of the flat rooftop surfaces into Grasshopper (a graphical algorithm editor that runs with the computer aided-design software Rhinoceros 3D), the developed parametric models allow planners to process a multitude of alternatives during the design process by interconnecting and coordinating design components simultaneously. Based on the results, the models evaluate the key scenarios for RA for the city roof landscapes of Vienna and RJC. By promoting a way of envisioning the urban space across its different layers of complexity, the idea is to look at rooftop agriculture as a possible driver for social and environmental sustainability.

The worlds population is becoming increasingly urban. By the year 2050, two-thirds of global population will live in cities (UN, 2014). Exploring holistic approaches to city design is crucial to manage tomorrows urban mutations. In fact, global sustainability depends on how urban systems will be managed in the 21st century (Ferrão & Fernández, 2013). A shift towards innovative planning solutions that are supportive of both social and environmental sustainability is imperative. Rooftop Agriculture (RA) could play a role in this transformation process. Rooftop gardens are multifunctional; hence provide several advantages such as enhancing biodiversity conservation, reducing flood risks or mitigating the urban heat island effect (Mentens et al., 2005). In many cities, due to urban pressure and land speculation, vacant space is rare.