As the bones and muscles of our built environment, engineering structures support all kind of societal activities. However, they consume huge amounts of resources and significantly contribute to impact on our environment. Structural design codes play an important matter in this regard since they regulate the use of materials by use of prescribed decision rules. These relatively simple and generalized rules offer significant potential for improvement. Grounded on risk-based optimization approaches, this paper explores this potential in connection with the design of reinforced concrete floor systems. Assuming a large variety of realistic design situations, representative sets of such members are defined and designed according to the semi-probabilistic safety concept in the Eurocodes. The benefits of a risk-informed structural design compared to the use of these standardized decision rules are demonstrated in terms of material consumption and CO2 emissions.