The construction of maritime infrastructure, such as waterways and seaports, often require large-scale dredging processes. These processes are often both energy-intensive, using various fuels and emit considerable amounts of greenhouse gases such as CO2. Studies on road infrastructure have introduced and successfully implemented a number of sophisticated approaches for assessing and reducing energy use and associated CO2 emissions at a project level. However, research on maritime infrastructure construction has primarily focused on dredging at an equipment level despite the promising opportunities of assessing and reducing the climate impact at a project level. This study proposes a workflow for assessing the energy use and associated CO2 emissions of maritime infrastructure projects and demonstrates its use in a case study. The case study shows that these types of assessments are possible to conduct which also implies that alternative scenarios, such as different material uses, equipment or design choices can be compared. In practical terms project managers can benefit from such assessments and comparisons to lower the overall climate impact of their maritime infrastructure projects.