Sustainable construction based on green roofs designed to retain rainwater and provide food: An LCA compared to conventional roofs

Urban Farm DB summary

A life cycle assessment (LCA) comparing the environmental performance of a conventional ceramic roof (CR) and a modular green roof (GR) planted with the edible species Pereskia aculeata. Primary data came from experimental GR prototypes monitored for one year, including irrigation volumes, plant development and rainwater retention across 50 rainfall events; secondary data were modeled from the ecoinvent database and literature. The analysis had three stages: comparing CR and GR construction and first-year use, sensitivity/uncertainty analysis of alternative GR materials, and a 30-year projection of use-phase impacts. In stage one, GR outperformed CR in 11 of 14 impact categories, with total normalized impacts 13% lower; 80% of CR's impact came from ceramic tile production, while in GR polymer components dominated, with polypropylene accounting for 82% of fossil depletion and polyester for 95% of ozone depletion. Substituting alternative polymers for the module and filter layers cut marine and freshwater ecotoxicity by over 70%. The optimized GR scenario had 71% lower normalized impacts than CR and outperformed it in 13 of 14 categories, with the 30-year projection confirming GR's continued advantage.