More than the sum of the parts: System analysis of the usability of roofs in housing estates

Toboso-Chavero, Susana; Villalba, Gara; Gabarrell, Xavier; Madrid-López, Cristina

https://doi.org/10.1111/jiec.13114

Housing estates, that is, mass social housing on middle‐ and high‐rise apartment blocks, in urban areas are found all over the world with very similar constructive patterns and a multiplicity of environmental and socio‐economic problems. In this regard, such areas are optimal for the implementation of a roof mosaic which involves applying a combination of urban farming, solar energy, and harvesting rainwater systems (decentralized systems) on unoccupied roofs. To design sustainable and productive roof mosaic scenarios, we develop an integrated framework through a multi‐scale (municipality, building, and household) and multi‐dimensional analysis (environmental and socio‐economic, structural, and functional) to optimize the supply of essential resources (food, energy, and water). The proposed workflow was applied to a housing estate to rehabilitate unused rooftops (66,433 m²). First, using the Multi‐Scale Integrated Analysis of Societal and Ecosystem Metabolism methodology, we determined metabolic rates across buildings and municipality levels, which did not vary significantly (12.60–14.50 g/h for vegetables, 0.82–1.11 MJ/h for electricity, 0.80–1.11 MJ/h for heating, and 5.62–6.59 L/h for water). Second, based on a participatory process involving stakeholders to qualitatively analyze potential scenarios further in terms of preferences, five scenarios were chosen. These rooftop scenarios were found to improve the resource self‐sufficiency of housing estate residents by providing 42–53% of their vegetable consumption, 9–35% of their electricity use, and 38–200% of their water needs depending on the scenario. Boosting new urban spaces of resource production involves citizens in sites which face social and economic needs.