Green infrastructure, such as green roofs/walls, plays a key role in addressing urban problems. Despite the well-established sustainable mentality, aspects such as aesthetics, recreation, and welfare are still the main drivers for undertaking such investments. Several studies have focused on proving the benefits of green infrastructure, namely, thermal insulation, air quality, and others. However, significant soft benefits have not yet been properly addressed. It is, therefore, important to understand how much citizens are willing to invest in those mitigating measures and list the aspects that influence that value. This study suggests a methodology based on stated preferences to evaluate the willingness-to-pay of owner/tenants for green roofs/walls in residential buildings and determine the influence of multiple factors. Results show that consumers reveal higher willingness-to-pay for accessible green roofs. Knowledge of benefits and the accessibility of green roofs have a great impact on the willingness-to-pay. Recreation benefit is at the forefront of individuals’ concerns; even more than aesthetics.

Green roofs and living walls are considered effective solutions for improving the environmental integrity of urbanized areas and the overall performance of buildings. Proposals are emerging not just for buildings but also for existing transport infrastructures that have needs/problems that can be met or addressed by such solutions. However, the economic feasibility of such sustainable solutions has not yet been clarified. This study presents a methodological approach to performing cost–benefit analyses of greening urban transport infrastructures at the separate financial, economic, and socioenvironmental levels. Infrastructure, user, and environmental dimensions are also assessed. Whole life cycle costs and socioenvironmental benefits are considered together. The methodology is applied to one of the main stations in Lisbon, Portugal: Entrecampos Railway Station. Five different case study alternatives for the station’s retrofit with green infrastructures are compared to its current situation. The cost–benefit analysis demonstrated that all five greening alternatives are economically feasible. For a 50-year life cycle and a 3.36% discount rate, the net present value ranged between EUR 734,700 and EUR 7,733,279. A sensitivity analysis was also performed, revealing a high degree of influence of discount and inflation rates, recreation, aesthetics improvement, well-being, and the station noise reduction on the net present value, ranging from 1.5 to 9%.

Green infrastructure has been applied in urban areas to mitigate the negative effects of urbanization and promote the efficient use of resources. This study suggests a methodology for assessing the economic value of installing green roofs and green walls in public buildings, particularly in primary schools. The economic evaluation considers costs and benefits from three perspectives—(i) infrastructure, (ii) users, and (iii) environment—using three levels of analysis (i) financial, (ii) economic, and (iii) socio-environmental. The methodology is applied to ten alternative green roofs/walls scenarios in two primary schools in Lisbon, Portugal, for validation purposes. The cost-benefit analysis is carried out for a 40 and 50-year life cycle, using a 6.67% discount rate. The results show that all scenarios are feasible. The final benefit-cost ratios range between 3.01 and 34.99. A sensitivity analysis shows that the installation cost, esthetic improvement, and increased sound insulation have a significant impact on the results.