LCA-based study on structural retrofit options for masonry buildings

Purpose: Over the last decade, the rehabilitation/renovation of existing buildings has increasingly attracted the attention of scientific community. Many studies focus intensely on the mechanical and energy performance of retrofitted/renovated existing structures, while few works address the environmental impact of such operations. In the present study, the environmental impact of typical retrofit operations, referred to masonry structures, is assessed. In particular, four different structural options are investigated: local replacement of damaged masonry, mortar injection, steel chain installation, and grid-reinforced mortar application. Each different option is analyzed with reference to proper normalized quantities. Thus, the results of this analysis can be used to compute the environmental impact of real large-scale retrofit operations, once the amount/extension of them is defined in the design stage. The final purpose is to give to designers the opportunity to monitor the environmental impact of different retrofit strategies and, once structural requirements are satisfied, identify for each real case the most suitable retrofit option. Methods: The environmental impact of the structural retrofit options is assessed by means of a life-cycle assessment (LCA) approach. A cradle to grave system boundary is considered for each retrofit process. The results of the environmental analysis are presented according to the data format of the Environmental Product Declaration (EPD) standard. Indeed, the environmental outcomes are expressed through six impact categories: global warming, ozone depletion, eutrophication, acidification, photochemical oxidation, and nonrenewable energy. Results and discussion: For each retrofit option, the interpretation analysis is conducted in order to define which element, material, or process mainly influenced the LCA results. In addition, the results revealed that the recycling of waste materials provides environmental benefits in all the categories of the LCA outcomes. It is also pointed out that a comparison between the four investigated options would be meaningful only once the exact amount of each operation is defined for a specific retrofit case. Conclusions: This paper provides a systematic approach and environmental data to drive the selection and identification of structural retrofit options for existing buildings, in terms of sustainability performance. The final aim of this work is also to provide researchers and practitioners, with a better understanding of the sustainability aspects of retrofit operations. In fact, the environmental impacts of the retrofit options here investigated can be used for future research/practical activities, to monitor and control the environmental impact of structural retrofit operations of existing masonry buildings