Closing Water Cycles in the Built Environment through Nature-Based Solutions: The Contribution of Vertical Greening Systems and Green Roofs

Water in the city is typically exploited in a linear process, in which most of it is polluted, treated, and discharged; during this process, valuable nutrients are lost in the treatment process instead of being cycled back and used in urban agriculture or green space. The purpose of this paper is to advance a new paradigm to close water cycles in cities via the implementation of naturebased solutions units (NBS_u), with a particular focus on building greening elements, such as green roofs (GRs) and vertical greening systems (VGS). The hypothesis is that such “circular systems” can provide substantial ecosystem services and minimize environmental degradation. Our method is twofold: we first examine these systems from a life-cycle point of view, assessing not only the inputs of conventional and alternative materials, but the ongoing input of water that is required for irrigation. Secondly, the evapotranspiration performance of VGS in Copenhagen, Berlin, Lisbon, Rome, Istanbul, and Tel Aviv, cities with different climatic, architectural, and sociocultural contexts have been simulated using a verticalized ET0 approach, assessing rainwater runoff and greywater as irrigation resources. The water cycling performance of VGS in the mentioned cities would be sufficient at recycling 44% (Lisbon) to 100% (Berlin, Istanbul) of all accruing rainwater roof–runoff, if water shortages in dry months are bridged by greywater. Then, 27–53% of the greywater accruing in a building could be managed on its greened surface. In conclusion, we address the gaps in the current knowledge and policies identified in the different stages of analyses, such as the lack of comprehensive life cycle assessment studies that quantify the complete “water footprint” of building greening systems.info:eu-repo/semantics/publishedVersio

Towards a Cross-Sectoral View of Nature-Based Solutions for Enabling Circular Cities

A framework developed by the COST Action Circular City (an EU-funded network of 500+ scientists from 40+ countries; COST = Cooperation in Science and Technology) for addressing Urban Circularity Challenges (UCCs) with nature-based solutions (NBSs) was analyzed by various urban sectors which refer to different fields of activities for circular management of resources in cities (i.e., reducing use of resources and production of waste). The urban sectors comprise the built environment, urban water management, resource recovery, and urban farming. We present main findings from sector analyses, discuss different sector perspectives, and show ways to overcome these differences. The results reveal the potential of NBSs to address multiple sectors, as well as multiple UCCs. While water has been identified as a key element when using NBSs in the urban environment, most NBSs are interconnected and also present secondary benefits for other resources. Using representative examples, we discuss how a holistic and systemic approach could facilitate the circular use of resources in cities. Currently, there is often a disciplinary focus on one resource when applying NBSs. The full potential of NBSs to address multifunctionality is, thus, usually not fully accounted for. On the basis of our results, we conclude that experts from various disciplines can engage in a cross-sectoral exchange and identify the full potential of NBSs to recover resources in circular cities and provide secondary benefits to improve the livelihood for locals. This is an important first step toward the full multifunctionality potential enabling of NBSs

Facing Multiple Environmental Challenges through Maximizing the Co-Benefits of Nature-Based Solutions at a National Scale in Italy

The European Union is significantly investing in the Green Deal that introduces measures to guide Member States to face sustainability and health challenges, especially employing Nature-Based Solutions (NBS) in urban contexts. National governments need to develop appropriate strategies to coordinate local projects, face multiple challenges, and maximize NBS effectiveness. This paper aims to introduce a replicable methodology to integrate NBS into a multi-scale planning process to maximize their cost–benefits. Using Italy as a case study, we mapped three environmental challenges nationwide related to climate change and air pollution, identifying spatial groups of their co-occurrences. These groups serve as functional areas where 24 NBS were ranked for their ecosystem services supply and land cover. The results show eight different spatial groups, with 6% of the national territory showing no challenge, with 42% showing multiple challenges combined simultaneously. Seven NBS were high-performing in all groups: five implementable in permeable land covers (urban forests, infiltration basins, green corridors, large parks, heritage gardens), and two in impervious ones (intensive, semi-intensive green roofs). This work provides a strategic vision at the national scale to quantify and orient budget allocation, while on a municipal scale, the NBS ranking acts as a guideline for specific planning activities based on local issues

Tools for edible cities - a review of tools for planning and assessing edible nature-based solutions

In the last five years, European research and innovation programmes have prioritised the development of online catalogues and tools (handbooks, models, etc.) to facilitate the implementation and monitoring of Nature-Based Solutions (NBS). However, only a few catalogues and toolkits within European programmes are directly related to mainstreaming of NBS for food production (i.e., edible NBS). Therefore, the main aim of this paper is to present existing NBS tools through the eyes of productive urban landscapes. We reviewed 32 projects related to NBS and 50 tools were identified and characterised. Then, the six tools already available and provided indicators were further analysed in terms of their format and knowledge domains. Our main conclusion demonstrates that there is a lack of tools capable of supporting users for planning and implementing edible NBScalculating the food potential of a city and/or of individual edible NBS, including the needed resources for implementation and operation (water, nutrients, energy)and assessing their urban design value, environmental and socio-economic impacts. Moreover, when they do exist, there is a resistance to share the models and equations behind the tools to allow other projects to reuse or validate them, a fact which is contrary to the open science principles upheld by many public research agencies

A framework for addressing circularity challenges in cities with nature-based solutions

A novel framework is presented that aims to guide practitioners and decision makers toward a better understanding of the role of nature-based solutions (NBS) in the enhancement of resources management in cities, and the mainstreaming of NBS in the urban fabric. Existing frameworks describing the use of NBS to address urban challenges do not specifically consider circularity challenges. Thus, the new framework provides the following: (1) a comprehensive set of Urban Circularity Challenges (UCCs)(2) a set of more than fifty NBS units and NBS interventions thoroughly assessed in terms of their potential to address UCCsand (3) an analysis of input and output resource streams, which are both required for and produced during operation of NBS. The new framework aims to facilitate the coupling of individual NBS units and NBS interventions with NBS that enable circular economy solutions

Nature-Based Solutions and Circularity in Cities

Cities worldwide are facing a number of serious challenges including population growth, resource depletion, climate change, and degradation of ecosystems. To cope with these challenges, the transformation of our cities into sustainable systems using a holistic approach is required. The pathway to this urban transition is adopting the concept of circular economy for resource management. In this way, resources are kept and reused within the city. Nature-based solutions can be implemented for these tasks, and besides the circularity, they can provide additional benefits for the urbanites and the urban environment in general. This paper describes which urban challenges related to circularity can be addressed through nature-based solutions. This systematic review was developed within the COST Action CA17133 Circular City that investigates how nature-based solutions can be used to progress the circular economy in the urban built environment

How Nature-Based Solutions can Contribute to Enhance Circularity in Cities

Environmental education in different disciplines puts an accent on acquiring specialised knowledge and, while this remains essential, fostering knowledge alone, without links to real life, personal experiences, competencies, and values, is insufficient. Nature-based solutions (NBS) have the potential to be used as an educational framework that requires critical system thinking, a crucial component of truly democratic active citizenship, and raises awareness about global environmental, social, and economic issues. On the basis of NBS-related environmental education materials, we present in this chapter selected case studies that describe education for three main stakeholder groups. Concerning pupils and students, these are examples for schools and higher education, as well as pilot installations from Italy, Spain, Slovenia, Portugal, Turkey, and Germany. Different forms of facilities or organisations are included to demonstrate the possibilities of NBS-related education for practitioners. The offers for the general public comprise a mobile exhibition/demonstration unit, a social project and an animation video. Additionally, existing online platforms for knowledge sharing are summarised. The NBS concept has potential to assist the transition from current conventional education paradigms towards to a more critical systemic thinking to foster environmental citizenship as a base for environmental, social-economic, political, economic, and cultural changes on local, national, and global scales