Economic and environmental feasibility of domestic biogas systems in low-income housing projects in Egypt: a cost–benefit analysis within a sustainability framework

Abstract Low-income housing projects in Egypt face several economic and environmental challenges, particularly rising energy costs and limited integration of renewable energy sources, which are placing increasing pressure on households and public budgets. In this context, domestic biogas systems are a promising solution that can simultaneously enhance economic efficiency and environmental sustainability. This study evaluates the economic and environmental feasibility of integrating biogas units into low-income housing projects in Egypt through an empirical assessment of three case studies in Upper Egypt (Aswan, Nagaa Hammadi, and Esna). A Cost–Benefit Analysis (CBA) framework is employed to quantify energy savings, investment performance, and sustainability impacts at both the household and project scales. The results indicate that the proposed biogas systems can reduce household energy expenditures by approximately 35–40%, with a payback period of less than one year (approximately 10 months). In addition to financial benefits, the system contributes to significant reductions in carbon emissions and improvements in indoor environmental quality. The findings suggest that integration is a practical pathway to achieving Egypt’s Sustainable Development Goals (SDGs) by 2030.