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This study applied Life Cycle Assessment (LCA) to compare the environmental performance of a conventional Ceramic Roof (CR) and a modular Green Roof (GR). As a novel contribution, the GR system was designed using Pereskia aculeata , a resilient, edible, and underutilized plant species, and included the analysis of rainwater retention impacts during the roof's use phase. The methodology was structured in three stages: (1) comparison between CR and GR systems, considering construction and the roof's first year of use; (2) sensitivity analysis of alternative materials for GR components, complemented by uncertainty analysis; and (3) a 30-years projection of use-phase impacts. Primary data were obtained from GR experimental prototypes monitored over one year, including irrigation volumes, plant development, and rainwater retention from 50 rainfall events. Secondary data were modeled using the ecoinvent database and literature sources. In the first stage, GR outperformed CR in 11 of 14 impact categories, with total normalized impacts 13 % lower. In CR, 80 % of impacts were from ceramic tile production, while in GR, polymer components were most impactful, polypropylene accounted for 82 % of Fossil Depletion and polyester for 95 % of Ozone Depletion. Sensitivity analysis showed that substituting the module and filter layers' materials with alternative polymers in GR reduced Marine and Freshwater Ecotoxicity by over 70 %. The optimized GR scenario achieved 71 % lower normalized impacts than CR and performed better in 13 of 14 categories. The 30-years projection reinforced the GR's superior performance over time. In conclusion, GR demonstrated substantial environmental advantages over CR. Additionally, GR adds value through food production, making it a promising strategy for promoting urban agriculture. Further studies on cost, end-of-life impacts, and species selection are needed to support broader adoption.
Leite et al. (Tue,) studied this question.