Dutch ports face significant environmental challenges due to high greenhouse gas and air pollutant emissions from berthed ships engaged in essential operations. Entities like the Port of Rotterdam and research institutes produced emission inventories to gain insight into ports' environmental impact. 

However, existing emission inventories rely on fixed factors and overlook berthing duration and activities: they assume the same emission factors regardless of the operations performed by vessels. Thus hindering effective emission reduction strategies and infrastructure development. 

Consequently, the following research studies areas of improvement for the current emission calculation methods by including berthing time patterns. Then, it will apply this information to the Port of Rotterdam to test the new methodology.

The principal result that emerged from this work is that reality is far more complex than the most widely used models to represent it; luckily, the available data can still grasp this complexity. First, not all berthing events are equal, and the rarest ones still hold a considerable impact on the total berthing time. Additionally, the differences do not exist only as a matter of frequency and duration but also imply different energy requirements, as suggested by the interviewed parties. Consequently, a model based on a standard stop only reliably captures part of the behaviour of moored ships. Second, there is no universal relationship between standard industry size classes and time spent in port. Some ship types show a positive linear behaviour (the larger the ship, the longer the visit berthing time), while others show more complex relationships. Moreover, some fleet types belong to only a few classes; therefore, no size-related difference can be observed in the behaviour of berthed vessels. These considerations apply to metrics of volume (GT), maximum transportable weight (DWT), and also cargo capacity (TEU). Consequently, the size classes commonly used in the industry - which reflect the physical limits of channels, ports, and other waterways - might be insufficient to portray the in-port behaviour of all the fleet types. Third, most ships berth at a single location during a port visit, proving that the duration of a port visit could be the only way to identify different types of berthing events. Finally, even the interviews suggested that the system is much more complex than captured by the currently used models. The division by fleet type might be an oversimplification as the product transported and the ship type considerably influence the behaviour in port and energy consumption.

These results contrast with the emission calculation methodologies commonly used in literature and policy documents, indicating a widespread risk of policy and investment failure because partial data and oversimplified models of reality might have driven policy and economic decisions. Thus, institutions may have enacted regulations with potentially inefficient economic, environmental, and social returns. Consequently, improving the system's knowledge is essential for informed decision-making and risk minimization. This research has shown that this objective is not only reachable but could be achievable without exponentially increasing the required data.