The building sector is responsible for 40% of worldwide carbon emissions, of which 8% can be attributed to concrete construction. With an increased demand for housing, this percentage is bound to increase. This thesis sheds light on strategies for reducing the environmental impact of concrete construction by investigating the potential of structural optimization and additive manufacturing. It concludes that in its current state, additive manufacturing is not able to address the environmental impact. Therefore, other potential strategies were explored, resulting in the following hypothesis: Fabrication-aware, structurally optimized floor slabs can significantly reduce the environmental impact of concrete construction. This hypothesis resulted in a derivative-free – fabrication aware – optimization methodology combining shape and size optimization to find the optimal form of a thin-shell inspired flooring system. A life cycle assessment resulted in an overall environmental footprint reduction that ranges from 60.1% to 79.8% compared to conventional flooring systems in a hypothetical office building. This shows the effectivity of flooring systems that take advantage of membrane action and the impact of increasing structural efficiency to reduce the environmental footprint of concrete structures.