## 5 Discussion  
Literature review [5] confirmed the lack of studies using standardized methods to calculate costs and emissions related to inventory operations arising from periodic review (R, s, S) inventory systems implemented in the SC's echelon. Most research on green inventory management predominantly relies on simple inventory models that cannot accurately simulate real-world conditions. In contrast, periodic review (R, s, S) inventory systems with stochastic demand are still under-researched. Only three papers [37; 45; 46] analyzed the (R, s, S) model of the periodic review inventory system, simultaneously analyzing economic and environmental effects under different SC settings and with different goals. Figure 15: (**a**) Average G\({}_{\rm W}\) per year per R + LT group for a 5-day WS and FR 99.9%. (**b**) Average G\({}_{\rm W}\) per year per R + LT group for a 7-day WS and an FR 99.9%. Measurement of GHG emissions according to international standards, similar to the one used in this paper, is only in work [37]. The work [45] studied a supply chain with a manufacturer and suppliers of recycled and raw materials. This SC encompasses stochastic elements such as demands, returns, and collection lead times. Radio frequency identification (RFID) is implemented in the SC to determine if real-time inventory monitoring and information sharing can help the system attain environmental and economic benefits. The simulated market demand in this paper was stochastic, with Poisson distribution and backordering as a response to excess demand. Waste in the form of material from the end user market was considered. This paper analyses inventory, transportation, out-of-stock, setup, and production costs. GHG emissions from transportation activities are not observed. Numerical studies showed that using an RFID information-sharing strategy, the system could attain environmental benefits over different SC configurations, simultaneously providing better economic performance than the non-RFID system. In paper [46], a simulation model is developed to compare demand fulfillment, cost, and emission of a forest-based biomass supply chain for two types of periodic review inventory systems (R, s, S) and fixed order quantity inventory systems. Cost components that are considered are inventory, transportation, and operational costs. Demand is not explicitly defined, and lost sale is measured as a response to excess demand. This research showed that a fixed order quantity system often results in higher demand fulfillment. However, it has a higher cost and CO\({}_{2}\)e emissions compared to the periodic review (R, s, S) inventory system. In both inventory systems, the transportation cost has the highest contribution to the total cost, ranging from 50% to 82%. The grinding operation contributes the most to the total CO\({}_{2}\)e emission in both inventory systems. The results showed that the selection of the inventory system impacted the annual demand fulfillment slightly but considerably affected the total cost and the total CO\({}_{2}\)e emission of the supply chain. Finally, work [37] has the most similar inventory and SC model to this paper. It considers the periodic review (R, s, S) inventory system under stochastic, normally distributed demand with lost sales. Environmental impact arising from transportation activities is measured according to, at that time valid, European norm EN 16258. Research considers ordering, transportation, holding, and penalty costs similar to those of this paper. Comparing this paper to [37], several essential differences in model setup and, consequently, simulation outputs arise. Firstly, [37] considers only one review period, i.e., R = 1, significantly limiting and simplifying the simulation model. Secondly, the complexity of other SC parameters is lower; for instance, the observed period is 90 days, whereas, in our paper, it is 365 days, giving much better information on the performed inventory system and echelon within the SC.