Eco-engineering has a crucial role in defining and achieving the sustainability credentials of a civil engineering project. Better eco-engineering practices would help better in reducing the adverse impacts on the environment and society, but also on the financial performance of the project. However, the assessment of the sustainability effects of eco-engineering strategies can be challenging, as the treatment of this topic has been neglected in the scientific literature. The challenges lie in balancing the project delivery objectives with the sustainable design that will ensure appropriate and satisfactory environmental and financial performance and deliver social benefits such as ecosystem services. In order to achieve better practice and advance the knowledge in the field, there is a need for broader analysis of completed eco-engineering projects applied at different spatio-temporal scales. The aim of this study was to critically analyse 23 eco-engineering case studies provided by the ECOMED project partners using a life cycle analysis through a single sustainability framework based on a relatively small set of key performance indicators (KPIs), which reflect the principles of sustainability, and which are not contextual for eco-engineering projects. The objectives of this study are twofold: (i) to highlight areas of best practice and potential enhancement in the application of eco-engineering strategies, and (ii) to propose refinement and enhancement of the existing framework with KPIs contextual to eco-engineering projects. The results of the study suggest that the feasibility, mobilisation, and the long-term stages of an eco-engineering project are the most sustainable project stages, while the award, construction, and monitoring stages could generally benefit from a range of enhancements including benefits stemming from double-loop learning and a common basis for the specification and quantification of the financial resources needed to apply eco-engineering strategies. The outcomes of this study will benefit decision makers and eco-engineering practitioners alike in terms of not only raising the sustainability profile of the projects they are involved in, but also in terms of more efficient and cost-effective application of eco-engineering strategies
