Current business models tend to base their total activity in the manufacturing, distribution and selling of industrial product with single use phase. But now, products with multiple use phases have to be considered regarding new economical and environmental pressures. In that case, the related complex life cycles have to be modelled and assessed by designers' teams for a better understanding of their whole performance. This paper focuses on the remanufacturing strategy. This study shows how to establish comparative assessments of remanufactured products life cycles vs. classical life cycle scenarios from an environmental point of view. The final objective is to provide easy to use methods and tools for designers to allow them quantifying the environmental benefits related to the use of a closed loop strategy. The approach is illustrated by a case study from the industry: a truck injector.