This research aims to explore the use of vegetation and nets to collect water from fog on facades to meet the needs of buildings’ functional requirements, particularly outdoor thermal comfort, water demands, and encouraging sustainability by suggesting a new architectural green–blue wall system. The system is posited to be applicable within an urban context, given its minimal spatial requirements and adaptability to existing structures. However, similar challenges to those encountered by green walls are anticipated, wherein the provision of sustainable benefits is offset by the demands of maintenance and associated additional costs. For this reason, this paper is mainly divided into two parts: in the first part, green facades are explained, referring to their effect on urban environment, including thermal comfort, pollution absorption, noise pollution, and well-being, as well as types of plants to apply on green walls; the second part focuses on the fog collector as an irrigation system for green walls, analyzing its components, structure, and fabric, to identify its development margins in the construction industry. Fog harvesting initiatives predominantly focus on rural regions to cater to agricultural demands; however, limiting fog harvesting to agricultural settings is considered insufficient, as it represents a crucial solution for addressing water challenges in specific urban environments. Nevertheless, it is worth investigating the fog collector’s potential for integrating water supply in urban environments as well. The study focuses on exploring the environmental benefits of fog harvesting and green walls, particularly through their combined implementation. The proposed review is significant for guiding the integration of a device into green facades, ensuring water self-sufficiency while concurrently addressing air purification, noise reduction, and thermal comfort for pedestrians and urban inhabitants. Nevertheless, it is worth investigating the fog collector’s potential for integrating water supply in urban environments as well. The proposed review is, therefore, useful for integrating a device represented by the fog harvesting system, also identified in the text as the blue system, into the design of green facades, identified in the text as the green system, integrating the blue element in the design of the green wall to make them water self-sufficient and at the same time purifying the air, reducing noise pollution, or giving thermal comfort to pedestrians and inhabitants of the urban context.

Water emergency is one of the terrible effects of climate change; it is defined as the Blue gold of twenty-first century. In this scenario, fog stands as a potential alternative water resource. Many territories are affected by fog phenomenon; here fog collectors have been developed to extract water from humid mass of air. The aim of this paper is to explore the application of this technology in building sector. The Large Fog Collector is the device commonly used for these projects; it is a textile structure, composed of a mesh, two poles and cables. The exploitation of conventional water resources implies a massive distribution system with significant energy consumption and costs. Otherwise, fog harvesting is a passive system; it relieves the stress upon freshwater resources. Nowadays, fog collectors are low tech devices, and fog harvesting projects are commonly developed in arid areas for agricultural and reforestation purposes. Nevertheless, taking advantage of the vertical development of the device, this textile structure shall be integrated in façade, to promote resilient constructions and make buildings water self-sufficient. The paper explores the design criteria for the development of a novel concept of smart water collecting façade. It can promote also shading effect, reducing the use of cooling system, energy demand, so lowering the ecological footprint. Depending on fog Liquid Water Content, the collected water can be used for the irrigation of green roofs, gardens or in an optimal scenario also for domestic use. The analysis of local weather data is crucial to extend the territories where this system can be applied; but, more important, the improvement of the device’s technology is essential to implement it in new application fields. Keywords Fog harvesting Water self-sufficiency Smart façade Textile architecture Resilient construction

The perspective of future sustainable urban environments focuses on buildings that not only achieve energy efficiency but also actively contribute to sustainable water use. This chapter addresses the pressing challenges of urban water systems amid increasing water scarcity, exploring how innovative passive solutions like fog harvesting can complement traditional water sources and improve the energy efficiency of buildings. It examines the operational mechanisms of fog harvesting, the required atmospheric conditions, and its application in both urban and rural contexts. Case studies and water collection data are analyzed to showcase its potential. Particular attention is given to integrating fog harvesting into building envelopes, such as double-skin facades, which can collect water while reducing energy consumption in buildings through shading. Lastly, the chapter discusses the limitations of fog harvesting technology, its impact on urban water consumption, and its potential role in shaping a sustainable built environment.

Fog harvesting, an ancient water extraction technique, has gained renewed attention in recent years with the introduction of the Fog Water Collector. Comprising a mesh and supporting structure, this collector has proven effective in extracting water from atmospheric moist air. The Raschel mesh, initially designed for agricultural purposes, has become the predominant choice due to its affordability and widespread availability. Current research endeavors aim to enhance fog water yield by optimizing both collector design and mesh properties.While Raschel mesh coatings have traditionally been explored to improve efficiency, recent findings suggest that alternative meshes may outperform the conventional Raschel mesh. However, challenges persist in understanding the resistance, lifespan, and maintenance requirements of these newer materials.Our research takes a systematic approach to address this gap by assessing the durability of various fog harvesting meshes under laboratory conditions. A series of standardized tests are conducted to evaluate their efficiency, providing insights into the intricate relationship between cost, water collection efficiency, duration, and environmental impact. The study aims to inform decision-making processes surrounding fog harvesting mesh selection, considering factors such as initial investment, operational efficiency, and long-term sustainability.By conducting these analyses in a controlled laboratory environment, we aim to provide valuable insights without the logistical challenges associated with field studies. This approach allows for a thorough examination of fog harvesting mesh performance, contributing to the broader understanding of NRWIs and their potential applications at different scales.