Nowadays the European attention on impacts produced by the construction sector leads to analyse new ways to conceive structures. Buildings should satisfy not only structural requirements but also the environmental, social and economic ones in accordance to the principles of Sustainable Development. In line with that a holistic balance among these requirements is needed to reach the goal of a sustainable construction. In particular, steel as a building material has undoubtful and inherent advantages in this respect, above all for its mature loop of recycling. The application of the Life Cycle Assessment (LCA) methodology has become a fundamental issue for the sustainable structural design. Indeed, LCA allows engineers and architects to assess the environmental sustainability throughout the whole life-cycle of a building, but it can also result into a tool to make decisions and to control costs. This paper proposes an approach to include environmental issues in structural design. In order to obtain a global assessment parameter to compare alternative design solutions, the need to consider structural and environmental analysis in economic terms is discussed. In particular, the environmental results in terms of CO2 emissions and energy consumptions have to be transformed into costs.