2.2 Life Cycle Assessment Zust and Wagner [24] explained four phases of the product life cycle: (1) product definition, (2) product development, (3) product manufacturing and marketing, and (4) product usage. At each of these phases, there exists a definition of objectives, activities, and deliverables for the next phase. Keys [16] explained that during the conceptual model phase, various design models of the product are generated. From these conceptual models, requirements, and specifications will evolve decisions for breadboard and brassbound models. Within the LCA framework, the greatest challenge is the assessment of the impacts associated with environmental releases during the manufacturing, transportation, use and disposal of products. Also, the Hewlett-Packard addressed the life-cycle issue by prototyping software, defining development and phases, and standardizing modules and packages [29]. 2.2 Life Cycle Assessment Zust and Wagner [24] explained four phases of the product life cycle: (1) product definition, (2) product development, (3) product manufacturing and marketing, and (4) product usage. At each of these phases, there exists a definition of objectives, activities, and deliverables for the next phase. Keys [16] explained that during the conceptual model phase, various design models of the product are generated. From these conceptual models, requirements, and specifications will evolve decisions for breadboard and brassbound models. Within the LCA framework, the greatest challenge is the assessment of the impacts associated with environmental releases during the manufacturing, transportation, use and disposal of products. Also, the Hewlett-Packard addressed the life-cycle issue by prototyping software, defining development and phases, and standardizing modules and packages [29].