This paper develops a dynamic regression model to quantify the contribution of key external factors to operational energy efficiency of ships. On this basis, kernel density estimation is applied to explore distribution patterns of fluctuations in operational performance. An empirical analysis based on these methods show that distribution of fluctuations in Energy Efficiency Operational Indicator (EEOI) is leptokurtic and fat tailed, rather than a normal one. Around 85% of fluctuations in EEOI can be jointly explained by capacity utilization and sailing speed, while the rest depend on other external factors largely beyond control. The variations in capacity utilization and sailing speed cannot be fully passed on to the energy efficiency performance of ships, due to complex interactions between various external factors. The application of the methods is demonstrated, showing a potential approach to develop a rating mechanism for use in the legally binding framework on operational energy efficiency of ships.

本文开发了一个动态回归模型来量化关键外部因素对船舶运营能效的贡献。在此基础上，应用核密度估计来探索运营绩效波动的分布模式。基于这些方法的实证分析表明，能效运行指标（EEOI）的波动分布是瘦高的、肥尾的，而不是正常的。大约 85% 的 EEOI 波动可以由运力利用率和航行速度共同解释，而其余的则取决于其他很大程度上无法控制的外部因素。由于各种外部因素之间复杂的相互作用，运力利用率和航行速度的变化不能完全传递到船舶的能效性能上。