Understanding the environmental impacts of residential water consumption in Brazil: Integrating the building stock with life cycle assessment

Household water consumption is of great interest due to its impact on water resources and the overall sustainability of buildings. In Brazil, even though households do not represent the most significant national water consumption among the different sectors, such a typology has several complexities for water supply, including long distribution lines, high loss rates, and the need for gauging and guaranteeing potability. Therefore, understanding the impact of water consumption in dwellings is of national interest. This study used top-down and bottom-up approaches to assess and characterise water consumption in dwellings based on Life Cycle Assessment (LCA) modelling. The main results include the differentiation of the impact concerning residential water consumption for the different regions of Brazil, ranging from 42 to 231 kgCO_2-eq/dwelling/year. For the single score indicator, which aggregates multiple environmental impacts into a single weighted value, greater relevance is given to water scarcity. Comparisons with energy consumption also helped to identify the relevance of phase B7 (operational water consumption phase) in the Whole Building Life Cycle Assessment (WBLCA) scope. Finally, the bottom-up analysis showed the need to reduce the water consumption of specific appliances. Adaptations to reduce shower water consumption and use rainwater to supply water to non-potable uses are essential strategies for reducing the final impact of residential buildings in the context of WBLCA. While the method’s replicability supports its global use, further research is necessary to explore its implications for non-residential buildings, fostering broader insights into sustainable practices.