Lowering environmental effects has lately been a key objective of structural optimization due to the significant amount of CO2 emissions in the civil engineering sector and the increased attention on environmental concerns and sustainable development. This thesis introduces an approach for the simultaneous optimization of steel space frame structures’ size, shape, and topology. The study’s originality stems from the specification of the objective function, which takes into consideration environmental issues by integrating the Life Cycle Assessment method in addition to conventional mass minimization. More specifically, the ideal number of elements, in terms of beams and nodes, has been investigated based on manufacturing and practical considerations.