This paper reports the development of novel green bio-composite mortars obtained by reusing mussel shells, a waste from the fish canning industry, as recycled aggregate, used for the first time in total substitution to the traditional sand. It suggests that this is a valid alternative to their usual disposal in landfills because the organic matter is potentially dangerous to humans and the environment. Different waste-based cementitious mixes were tested and compared to a traditional OPC mortar. The manufacturing process was performed at ambient conditions (20 °C, 65% RH) with highly sustainable results and consisted of simple operative steps reproducible in a real building site. The engineering performance was investigated to preliminarily assess the novel material potentials in construction. The main results showed that recycling mussel shells as aggregate while considerably decreasing the mechanical resistance (up to 60% in bending and 50% in compression), mixes could still find proper building applications (either structural, light partition, and plastering) according to the relevant standards. Moreover, the bulk density resulted up to 30% lower and the energy behavior was improved up to 40%, making the developed mortars highly suitable for promising energy-saving uses. Finally, the waste recycling about halves the materials cost and could also grant further financial saving for the fish industry. To conclude, the large amount of reused bio-waste not only represents a valid alternative to their usual disposal in landfills, but also makes the considered mortars suitable for building applications and promising candidates for the Minimum Environmental Criteria certification, in light of the EU Green Transition, and in line with the principles of the circular economy.

Nature-Based Solutions offer a concrete opportunity to integrate nature into cities and strengthen their resilience, in response to global challenges related to climate change, biodiversity loss, and water management, which are exacerbated by urban expansion and its impacts on the built environment. This study aims to analyze various European policies and urban greening practices, considering not only some European Union member states but also other cities geographically located in Europe. The main goal is to explore how these solutions are used in various European cities to address environmental challenges and improve urban quality of life. The study highlights the growing role of greening strategies in EU urban policies as key tools to tackle global challenges. It finds that green interventions—such as green roofs, façades, and green urban spaces—offer multifunctional benefits, but their effectiveness relies on integrated planning, strong public–private cooperation, and active community involvement. Key challenges include the limited scalability of these solutions in dense or economically constrained areas and the need for long-term financial and institutional support. Overall, the study highlights that greening is not merely aesthetic but central to building regenerative and climate-resilient cities.

The design of post-emergency shelters is critical for mitigating the impacts of the numerous disasters occurring globally. Unfortunately, these shelters are frequently constructed with insufficient attention to comfort levels and minimum standards for temporary refuge. This study examines wooden post-emergency shelters, which have become increasingly common in various refugee camps and regions worldwide. Using the Active House Protocol, a comprehensive comparative analysis of indoor comfort is conducted to propose innovative approaches to global design challenges, particularly in developing countries. To minimize the negative effects of disasters and increase sustainability, it is essential to explore the feasibility of designing comfortable shelters despite numerous obstacles, such as the limited availability of low-cost materials and the lack of skills of the local workforce. Various shelter configurations are analyzed, revealing that structures made from natural materials and designed with careful consideration of air circulation yielded the highest comfort values. Additionally, the study finds that wooden structures do not always provide the best solution, contrary to common practice. Inadequate comfort standards can lead to distress and psychological stress among occupants, highlighting the necessity to improve design and construction practices to ensure the well-being of disaster-affected populations. Finally, this study provides guidelines on the minimum requirements for the development of post-disaster shelters, advocating for solutions that are both simple and effective in rapidly addressing the critical situations that arise following disasters.