Bottom-up model for the sustainability assessment of rooftop-farming technologies potential in schools in Quito, Ecuador

Abstract

Rooftop-farming technologies can transform unexploited roofs into agricultural areas; and though studies have quantified the sustainability of diverse rooftop-farm systems, researchers lack a direct comparison between these farms using a unified sustainability index. Therefore the proposed bottom-up model aims to quantify the sustainability of rooftop-farm technologies application in school building stocks, thus permitting an objective comparison and ultimately selection of the best-fitted farm system. This model handles large building samples by combining Statistical Mining Techniques with the Integrated Value Model for Sustainability Assessment. It uses data on the economic, environmental and social aspects of the farms, and relates them to the technical limitations and functionality found in the host buildings. The model has three consecutive stages: 1) in the City Stage reference buildings are identified from the stock, 2) the Building Information Stage determines the logistics and infrastructure requirements; and, 3) the Farm Technology Stage quantifies the farms’ sustainability. This model was used to assess the potential implementation of three rooftop-farms (edible-green roofs, rooftop greenhouses and integrated rooftop greenhouses) in the primary school stock in Quito, Ecuador. Two reference buildings represented the primary school stock of the city; and, in both typologies, edible-green roofs obtained the highest sustainability values of 0.62 and 0.65. The environmental pillar was the most discriminant in which green-roofs achieved twice the sustainability values for the rooftop-greenhouses due to their larger rainwater harvesting capacity, thermal resistance and contribution to the increment of urban greenspaces.