This study focuses on including the environmental assessment of a process in its design. Two improvement targets can be considered to optimize the environmental efficiency of a production phase: a cleaner process, and the optimization of the assembly of the different product parts. This work makes it possible to apply life cycle assessment to product industrialization, and specifically to assembly lines. The reduction of the environmental impacts (EI) of the production phase can be achieved by modeling the assembly line and/or optimizing equipment choices and organization. To accomplish this, we developed a tool. In this tool,equipment EI are calculated using two databases: i) an equipment database, listing Equipment characteristics: lifetime, EI for individual functional units and use parameters; and ii) a consumption database, listing the consumables and energy EI. A comparison of the equipment EI is carried out for the same function, use conditions and functional unit. Equipment is then selected according to its EI. Finally, the tool determines the EI of the optimized assembly lin