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

Abstract

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. This article met the requirements for a gold-gold JIE data openness badge described at http://jie.click/badges.