Supply chain management seeks efficiency. Inefficiencies cause various types of waste and commensurate costs. Supply chain actors differ resulting in proximity issues. Proximity is introduced here as distances on four dimensions; organizational, geographical, cognitive and technological proximity. Industry 4.0 concepts can improve or even worsen each of the introduced proximity dimensions their influence on green supply chains. We propose a need for investigation at the nexus of Industry 4.0 and greening supply chains; proximity analysis provides a vehicle for this investigation.

Supply chain management seeks to get the right material, at the right time and place at minimal cost. Based on the type of product to be manufactured or assembled, different process chain types exist: 1) Make-to-Stock (MTS) for standard parts, 2) Assemble-to-Order (ATO) for components, 3) Make-to-Order (MTO) for prefabricated materials and 4) Engineer-to-Order (ETO) for customized products (Dallasega and Rauch, 2017). Different process chain types have different lead-times between order release and the product delivered to the manufacturer. ETO, our focus, requires usually long lead-times throughout the supply chain because components have to be engineered, produced and installed according to a specific customer order. It is often difficult to produce components on-demand and deliver them when needed for manufacture. As a result, this extended lead-time causes two kinds of problems: 1) Late deliveries and in the worst-case expensive production interruptions; or 2) Early deliveries that require a storing of engineered materials on-site increasing inventory costs such as obsolescence, holding costs, or damaging goods. Late and early deliveries create significant non-value adding activities like searching, waiting or excessive handling of components and high buffer levels throughout the supply chain. These kinds of waste create manufacturing cost increases and budget overruns. Supply chain actors may also have different physical and cognitive distances from each other that contribute to these inefficiencies and waste. Within this context we introduce the term proximity defined along four dimensions; organizational, geographical, cognitive and technological proximity (Dallasega et al., 2018). These proximity categories can be used to study the distances amongst suppliers and between suppliers and customers; and may influence environmental and green supply chain issues. • Organizational proximity: refers to levels of difference in organizational processes and routines between supplier-supplier and/or supplier-customer organizational relations. As an example, information systems characteristics may ease or cause organizational friction. As a practical example, the alignment between the supplier’s environmental management system, and the design for environment system of the customer may be poor; causing difficulties in greening of products. • Geographical proximity: an objective and subjective geographical distance between suppliers and the customer can increase coordination, logistics, and storage costs; in addition lead times, delay and rework risks, and risk perception are influenced. Large distances between suppliers and customers makes synchronization for on-demand production and just-in-time (JIT) delivery difficult. Subjective or perceived distances could be increased due to limited infrastructure or climate conditions.