From the point of view of NBS effectiveness, a group of 34 experts from research, municipalities, policy, and society proposed examples of potential metrics to assess the climate change adaptation and mitigation, and associated co-benefits. This was done in the ‘NBS to climate change mitigation and adaptation in urban areas’ workshop carried out in the context of the BIOCLIM project (Kabisch et al. 2016). The metrics are structured around four dimensions, namely, integrated environmental performance, health and well-being, citizen involvement, and transferability and monitoring. The proposed metrics are only examples, without a clear definition and methodology. However, some of them, such as ‘decrease in air pollution in temperature and CO₂ emissions’ or ‘number and share of people with access to a green or blue space’, might present a suitable base for NBS assessment. Several dimensions that are critical for an adequate NBS assessment, such as governance or NBS infrastructure performance, were not, or partially, considered. The proposed indicator should be taken as the first approach to a detailed NBS assessment, particularly related to health, well-being, and citizen engagement aspects. Table 5 presents some examples of metrics defined in the NBS assessment proposals.