Life cycle engineering case study: Automobile fender designs

Beginning with the goal and scope definition five different fender designs using steel, aluminum, PP/EPDM, PC/PBT and PPO/PA are described and the boundary conditions set. This exemplary case study demonstrates the general approach and beneficial uses of life cycle assessment and life cycle engineering. The inventory of the fenders shows that the steel design has advantages in terms of lower energy consumption during production. However, when the utilization phase of the fenders is considered, the overall energy consumption of the PP/EPDM fender is smaller due to the slight weight of the this polymer design. Concerning the life cycle impact assessment (LCIA), the global warming potential of the PP/EPDM design is the smallest of all the fender materials even during the production of the fenders. The inventory analysis shows that the utilization phase of automotive parts is dominated by fuel consumption and related emissions like CO2. Nevertheless the LCIA shows that some impacts are mainly determined in the production phase. For example, the global warming potential of nitrous oxide (N2O) released during PPO/PA material production cannot be compensated for the lower energy demand (and also lower CO2 emissions) during the utilization phase. Economic considerations are also discussed. As a parameter, the cost of parts was chosen. Parts costs depend on material costs, labor costs and other variable costs. In addition, the fixed costs for machines and tools were considered. Steel fenders have the smallest production costs, followed by the PP/EPDM design. Finally, in an overall valuation of the compared fender designs the best design considering primary energy demand, global warming potential, and part costs was investigated. In terms of the specified criteria, the PP/EPDM fender is the best design, however, the results lead to a variety of different conclusions.