Sustainable inventory models

Sustainability issues are currently becoming very important. The concern on this topic stresses the need to treat inventory management as a whole by integrating not only economic but also environmental and social objectives. Inventory models including these characteristics are known in the literature as sustainable inventory models and constitute the most recent research area for inventory models still growing. For that reason, this work aims to develop new sustainable inventory models including the wide inventory model’s theory developed since 1913. The main contribution of this work is the formulation of three inventory models with sustainability considerations. The first model uses one decision variable which is the lot size. In that model, a new mathematical expression to formulate the emissions of a company is proposed and an optimization procedure is developed using a Taylor polynomial. The second model includes two decision variables: the lot size and the maximum backordering quantity. This model also considers imperfect quality. For that model, a discontinuous function for the transport cost is included and a heuristic is proposed to face that problem. Finally, the third one is a multi-product sustainable inventory model that includes imperfect quality, as the second one, but also three constraints related with the number of orders, the required space and the carbon emissions constraint. These inventory models are helpful to make better decisions for companies that want to incorporate environmental and social criteria into their policies.