NbS Triple Win Toolkit: Economics and Finance 82 Other considerations Interaction of NbS project appraisal with Green Book review 2020.One of the core findings of the review of the Green Book in 2020was that many project proposals lacked a strong strategic direction. This leads to undue reliance being placed on benefit-cost ratioswhich may demonstrate poor strategic alignment. The triple win provides the strategic direction but there remains a risk that projects with monetised benefits (e.g. avoided cost approaches which value carbon or economic assets) will be prioritised over projects with qualitative evidence for the triple win. The review makes clear that there should be no threshold test for a benefit-cost ratio to pass inorder for a project to achieve funding. Further, it states that business case reviewers should be open to projects with lower benefit-costratios if they have a stronger strategic fit. It is important to notethat cost-effectiveness of benefit-cost ratios are only one part ofthe consideration into choosing between projects. There are other strategic factors which guide the decision-making process. Equally, cost-effectiveness metrics are an important way to ensure (or maximise the likelihood) that taxpayer money is spent as efficiently as possible given the data available and the prevailing uncertainties. However, more resources should be directed to both understanding and quantifying the significant impacts of the qualitative benefits which NbS generates and how these can be delivered and monitored across multiple locations and contexts, as well as the risks and uncertainties which are inherent in projects which engage with natural processes. More time and resources invested in these areas will strengthen the evidence base for the NbS qualitative benefits, the understanding of the risks and uncertainties of NbS projects in different locations and ecosystems across the world, and ensure that projects competing for funding are doing so in pursuance of wider strategic objectives both domestically and internationally. More business cases assessing the qualitative benefits of NbS and the continued attempts to quantify key benefits arising from NbS projects will also help build a frameworkfor assessing NbS projects which gives appropriate weight to the qualitative and monetised benefits across each of the triple win objectives. Lack of distributional impact assessment in NbS projects. Different types of NbS benefits have very different characteristics and manifest in different capacities for different stakeholders. An important limitation with using conventional benefit-cost ratios in NbS projects is that they are typically not disaggregated or weighted by who is the recipient of the benefits and who incurs the costs. This is especially relevant where benefits are both local (e.g. impact on local ecosystems and communities) and global (e.g. an NbS projects with a climate mitigation focus). It is important to understand the extent to which a high benefit-cost ratio arises because of global benefits which are less important or accessible by local stakeholders but are of interest and importance for public or global institutions, or because of the project activities which return cash or other social benefits to local communities. The majority of economic assessments of NbS are conducted before the project begins. It is important to note that many case studies found which demonstrate evidence of economic analysis are either a) relatively new and yet to report substantially on their results so far, b) academic studies which are designed to research the economic case for NbS, or c) conducted before the project begins. Whilst nearly all evidence of economic analysis found in the case study search includes some level of sensitivity analysis, such evidence should still be viewed as prospective. As mentioned in the previous subsection, there is clearly an underinvestment of rigorous ex-post economic analysis.To develop the evidence base and allow NbS to be comparedwith other projects requires investment in ex-post analysis and comparison with ex-ante appraisal to understand where benefitsand costs are under or overestimated, and how NbS projectscan be designed and run better in the future.