تعمیر و نگهداری محصول برای گسترش طول عمر و مصرف پایدار : رویکرد بهینه سازی

Sustainable consumption has been defined as “the consumption of goods and services that meet basic needs and quality of life without jeopardizing the needs of future generations” (OECD, 2002). Lifespan extension of durable products underpins sustainable consumption. This paper describes a novel approach to extend product lifespans by using product servicing that conceptualizes the interactions of a producer, a policy-maker, and multiple consumer segments having different price–demand relationships. We propose a multi-period mathematical optimization model that maximizes the producer's profit while optimizing the prices of different servicing options, production quantities, and inventory levels. A computational study elicits several insights about how the optimal production (or alternatively) consumption quantities are affected by the introduction of product servicing, and the effects of various product characteristics and government incentive or penalty levels on producer's profitability and on product servicing decisions. We conclude that quantitative optimization models are useful for evaluating the impacts of different regulatory policies, assessing the benefits of offering product servicing options, and investing in design for durability and serviceability.

Barber (2007) identifies four categories of initiatives to promote sustainability: consumption, investment, production, and distribution. Consumption initiatives generally involve notifying consumers about the impacts of their purchasing decisions; investment initiatives include government support of environmentally friendly products and manufacturing; distribution initiatives support marketing and advertising of green production methods, such as including environmental impact information on product labels; and production initiatives encourage the application of green production methods throughout the supply chain. Some producers undertake real innovations in product design rather than marginal improvements. More often than not, however, the benefits of any efficiency gains disappear in the so-called rebound effect (Ehrenfeld, 2001). In this syndrome, efficiency produces more consumer surplus which leads to more consumption, counterbalancing the potential benefits of eco-efficiency. Extending product lifespans combined with eco-efficiency to achieve sustainable consumption has been proposed by Cooper (2005), who suggests that decreasing the amount of consumption and waste can only work if the framework for the relationship between the consumer and producer is drastically altered. A survey of the literature reveals no suggestions on how producers might be compensated for their lack of production and sales revenue if they invest in extending product lifespans. Our proposed framework motivates producers to institute a process for servicing products for extended periods that relies on managing demand and government incentives/penalties. The contributions of this paper are (1) A conceptual framework of the roles that a producer, consumers and the government (policy-maker) can play to slow consumption through product servicing and government incentives. (2) A multi-period mathematical optimization model that assists the producer in optimizing the pricing, production, and inventory decisions that maximize profit assuming multiple servicing options, multiple consumer classes (segments), and government incentives/penalties to promote extended servicing contracts. (3) A computational study to gain insights into the impacts of different product characteristics and government penalty levels on producer's profitability and product servicing decisions. The remainder of the paper is organized as follows: Section 2 reviews the relevant literature. Section 3 presents the conceptual framework for sustainable consumption through lifespan extension and product servicing. Section 4 presents the mathematical optimization model of product servicing based upon the conceptual framework. Section 5 discusses the computational study to generate insights, and Section 6 presents conclusions and suggestions for future research.

This paper introduced a conceptual model of product servicing to support extending product lifespans, an essential requirement of sustainable consumption. Based on the conceptual model, a general mathematical multiple period optimization model was formulated to assist a producer in developing a menu of price and service coverage duration pairs that maximized total profit considering multiple consumer segments with different price–demand relationships. The model also considered producer's limited production capacity, servicing capacity, changing inventory and production cost, and government incentives or fees on sales depending on product's expected lifespan. Further, the mathematical model provides the producer with a tool to quantify the benefits of investing in more durable products and establishing product servicing systems. A computational study generated managerial insights into the relationships between product characteristics and the two performance measures, expected profit over the planning horizon, and PLWPS. The results showed that seven of the eight factors studied (average servicing cost, request for servicing probability, government fees/incentives, per unit production cost, rate of demand variation, demand pattern, and demand elasticity) significantly affected both performance measures. We found that the product's price elasticity of demand had the largest effect on average profit and on the PLWPS. Producers of elastic products such as many electronics, will benefit from our model to help them manage the production, pricing, and demand fulfillment decisions because our results show that profit and the PLWPS of elastic products are strongly sensitive to product characteristics such as demand pattern, rate of demand variation, production cost, etc. Although the analysis was simplified, such as assuming that demand of products is deterministic and demand for servicing is modeled as a discrete random variable, future research will relax these assumptions. We suggest that a fair assessment of the environmental benefits of the proposed servicing model should encompass the environmental impact of servicing operations. Our own future research will incorporate Life Cycle Assessment (LCA) study outcomes into the objective function of our proposed model in the form of environmental metrics (human health impact, resource depletion impact, and pollution) that are optimized in addition to profit. Variations of the model can be developed for determining regulatory fees or incentives that minimize consumption and reduce environmental impacts, but still maintain profitability. The penalty or fee-upon-sale should reflect the full cost of the product upon disposal in order to avoid the negative consequences of Extended Producer Responsibility attempts such as in Ontario, Canada, where customers were charged eco-fees that were higher than authorized because of complications in administering the detailed system (Ferguson, 2010), and in California where state and industry officials estimate that ineligible claims, totaling as much as $30 million, may have inadvertently been paid by the state to recyclers and collectors of e-waste (Knudson, 2010).