Proposal of "Marginal Reuse Rate" for Evaluating Reusability of Products

Abstract

While reuse is an effective life cycle option in terms of reduction of environmental loads and conservation of value of circulation, reuse has inherent difficulties. Our naive questions include why reuse of electric home appliances seems impossible while that of photocopiers succeeded. This paper clarifies that a critical factor for successful reuse is to balance supply and demand of reusable products and components. For representing this factor, this paper proposes an index named “marginal reuse rate, ” which indicates upper limit of reusability from the viewpoint of the balance. By using the marginal reuse rate, this paper analyses reusability of single use camera, photocopier, and automatic teller machine (ATM). These analyses clarified that the marginal reuse rate depends on the relation between sales period and product's lifetime and effective measures for increasing reusability differ according to the relations; namely, prolongation of the sales period for shorter life products, part commonization design among generations for middle life products, and controlling sales and disposal distributions for longer life products. The marginal reuse rate indicates that design of life cycle, in addition to product design, is indispensable for successful reuse. In this sense, the analysis with the marginal reuse rate is an indispensable tool for appropriate life cycle design.