Sustainability of wall construction techniques for self-built rural housing. A case study from Brazil

This study assesses the sustainability of eight wall construction alternatives suitable for self-built housing in rural informal settlements, comparing different building solutions in the Brazilian context. Housing affordability is a global challenge, particularly relevant in developing countries where informal settlements are prevalent. This research addresses the need for sustainable construction practices in these contexts, focusing specifically on wall construction as a critical building element. The study relies on MIVES, a multi-criteria decision-making method, to evaluate the environmental, economic, and social impacts of each alternative. The eight alternatives include variations of soil-cement blocks (precast and on-site produced), ceramic blocks, concrete blocks, and precast concrete panels, with and without mortar and plaster coatings. A hierarchical requirements tree, encompassing criteria and indicators related to resource consumption, emissions, cost, empowerment, safety, comfort, and innovation, was developed based on technical literature and expert knowledge. Weights for these criteria and indicators were determined using the Delphi technique. Value functions were used to standardize quantitative indicator values onto a 0-to-1 scale. This research aims to provide a structured framework for evaluating the sustainability performance of different wall construction techniques in rural informal settlements, thus providing valuable insights for informed decision-making in self-built housing projects. Results indicate that concrete blocks and precast concrete panels without coatings achieved the highest sustainability index, primarily due to their lower economic costs and environmental impacts. Conversely, ceramic blocks with coatings achieved the lowest sustainability performance. Alternatives without coatings were generally preferred due to their lower costs, aligning with real-world practices in rural areas where economic constraints govern material choices. However, these alternatives performed less favorably in terms of social sustainability, particularly in comfort and community acceptance. Sensitivity analysis confirmed the robustness of the evaluation framework across different weighting scenarios, with economic, environmental, and social biases leading to only minor ranking shifts. The findings highlight the importance of balancing cost-effectiveness with durability and habitability in self-built housing, emphasizing the need for innovative solutions, particularly in self-built soil-cement blocks, to improve sustainability while maintaining affordability.