The construction industry contributes about 40% of global emissions, mainly from material production. This study explores supplementary cementitious materials (SCMs) like rice husk ash, silica fume, and fly ash as partial cement replacements, along with seawater as an alternative to freshwater in concrete production, which consumes 9% of global industrial water. Using Philippine resort case studies, the research assesses SCMs’ environmental impact through global warming potential, seawater’s water footprint via the available water remaining indicator, and the economic feasibility of these alternatives. Fly ash reduced emissions, though transportation distances affected results. Seawater showed promise in conserving freshwater, while rice husk ash was the most cost-effective, as it was freely available. However, the analysis covered only concrete production costs. The findings confirm that alternative materials are sustainable and cost-effective, highlighting the importance of availability, context, and location in material optimization.