This study investigates the environmental and economic impacts of using two different concrete strength classes, C20/25 and C32/40, in the structural design of a four-storey residential building. The analysis was conducted according to Eurocode 2, using manual calculations in Excel and complemented with Bidcon software for life cycle assessment(LCA) and life cycle cost (LCC) analyses during the production phase (A1–A3). The results indicate that C32/40 requires approximately 17.9% less concrete volume compared to C20/25, particularly due to reduced dimensions of slabs, beams, andcolumns. This reduction leads to a marginal decrease in total CO₂ emissions (0.53%), despite the higher cement content in C32/40. Furthermore, the total material cost for C32/40 is about 1.9% lower than for C20/25. The findings suggest that higher-strength concrete can contribute to more material-efficient and cost-effective building solutions, while also slightly reducing climate impact. Future studies should expand the scope toinclude additional concrete classes, such as ultra-high-performance concrete (UHPC), and consider the full life cycle perspective.