Life Cycle Assessment of green roofs: A comprehensive review of methodological approaches and climate change impacts
Débora Pons Fiorentin, Mario Martín-Gamboa, Sandra Rafael, Paula Quinteiro
Abstract
Green roofs provide several environmental, economic, and social benefits making them crucial to promoting Sustainable Developments from the 2030 Agenda. Life Cycle Assessment (LCA) has been applied to evaluate and compare the environmental performance of green roofs, but a large variation of results can be found in the literature. A sample of 44 papers, encompassing different green roof types (extensive, semi-intensive, and intensive), and the number of layers with different materials were reviewed, based on a thorough analysis of methodological choices, including functional unit and the most evaluated impact category - climate change. The economic and social aspects of green roofs were analysed, indicating that geographical aspects and benefits of green roofs hugely influence economic performance, and there is a lack of social evaluations considering a life cycle perspective. Most of the reviewed papers addressed the extensive green roof type and the most common system boundary assessed was the cradle-to-grave. A high variability was observed for climate change results, ranging from 3.08 kg CO2eq to 155.88 kg CO2eq. Furthermore, climate change results revealed that there is no correlation between the type of green roof and the one with lower impact, which is due to the high heterogeneity of the methodological choices applied in the papers, and mainly due to the great contribution of the materials manufacturing stage to the environmental impacts. Currently, a more comprehensive approach integrating the three pillars of sustainability (environmental, economic, and social) in the research is needed.