Life Cycle Assessment of Roofing Systems in Buildings: Green Roofs vs. Conventional Roofs

Green roofs are roofing systems designed to reduce the environmental impact of buildings; however, the production of the materials used in their construction can generate significant impacts. This research aimed to measure the environmental impacts of the production and use of 1 m² of an extensive green roof, comparing the results with those of a conventional roof and other green roof systems reported in the literature (intensive and extensive).

To this end, Life Cycle Assessment (LCA) was used as the methodology, following the ISO 14040/14044 standards, and the impact calculation was performed using the openLCA 2.0^® software. The categories analyzed were: abiotic depletion of fossil fuels, terrestrial ecotoxicity, photochemical oxidation, global warming potential (100 years), and human toxicity.

The results showed a 5% reduction in terrestrial ecotoxicity and a 6% reduction in photochemical oxidation for the extensive green roof analyzed in this study. For fossil fuel depletion, 100-year global warming potential, and human toxicity, the green roof had higher impacts than the conventional roof, with increases of 10%, 4%, and 3%, respectively.

Although green roofs may cause higher production impacts, they can provide environmental benefits during use, such as pollutant removal. The better overall results of the extensive green roof highlight its potential as a more sustainable roofing option.

A contribution analysis revealed that the most polluting materials in both systems are the concrete and steel used in the supporting structure. Therefore, to improve the environmental performance of green roofs, it is recommended to use more sustainable materials and reduce the consumption of materials identified as the most polluting.