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Nature-based solutions (NBS) are frequently implemented without taking the system's perspective into account and with the main focus on technical and economic issues of implementation. This study was conducted to test the hypothesis on the potential synergistic effects between circularity and NBS to holistically tackle urban challenges. The main objective is to establish preliminary insights on the obstacles and perspectives of NBS integration and implementation, through a questionnaire set up by the network of experts gathered within the COST Action CA17133 Circular City. The following research questions arise: (i) what differences exist in the level of NBS application according to the variance of engaged countries; and (ii) what are the main obstacles and perspectives for the NBS implementation in order to holistically tackle urban challenges, enhancing the sustainable connection among urban environment, nature, and human well-being. To go beyond the current state-of-the-art and reflect on the research conducted within the Circular City Action, this study aims to open a multi-geographical academic dialogue across Europe and beyond and to move towards a holistic approach to circular cities. Accordingly, this study is: (1) multi-geographical and context-based, providing input for thirty-three EU countries and four non-EU countries to give an overview of the main obstacles and perspectives of NBS implementation, and (2) approach-directed, aiming to formulate a holistic approach to deal with societal challenges. This document intends to provide qualitative and quantitative insight into the potentials and obstacles of NBS implementation in Europe, as well as to motivate further discussion and research to achieve holistic and sustainable cities. [ABSTRACT FROM AUTHOR]

Thermal comfort assessments at local or micro-scales within urban areas can provide crucial insights for the urban adaptation strategies pertaining to climate-conscious urban planning and public health. However, the availability of long-term or mid-term daily or hourly meteorological data sets from urban environments remains a significant challenge even in the 21st century. Consequently, this study aimed to assess the thermal conditions in cities across the western part of the Balkan Peninsula, encompassing five countries (Slovenia, Croatia, Serbia, Bosnia and Herzegovina, and Montenegro), by utilizing the Physiological Equivalent Temperature (PET) index. Meteorological data sets, comprising air temperature, relative humidity, wind speed, and cloudiness, were collected from 32 national meteorological stations/measurement locations spanning the period from 2001 to 2020. The PET calculations were conducted based on meteorological data measured three times per day (7 a.m., 2 p.m., and 9 p.m.). Upon conducting a spatial analysis of the meteorological stations, it was observed that most of them (25 stations) were situated within built-up areas or urban suburbs, rendering them highly relevant for local or micro-scale climate and bioclimate assessments. The findings revealed that urban locations exhibited slightly higher PET heat stress levels, particularly during the summer season and at 2 p.m. Moreover, higher average PET values were observed in both urban and non-urban stations situated within a continental climate during warmer periods, such as summer. In contrast, during the colder seasons, namely winter and spring, higher PET values were prevalent in the Mediterranean region. Furthermore, the PET frequency analysis revealed a greater prevalence of extreme and severe heat stress levels in stations within continental climates, particularly those located in urban areas, as compared to stations in Mediterranean climates. In contrast, during the winter and spring seasons, monitoring stations in close proximity to the Adriatic Sea, characterized by a Mediterranean climate, exhibited significantly lower levels of cold stress compared to inland stations. Evidently, in addition to the climatic characteristics and surrounding terrain, the urban morphology significantly impacts the thermal conditions within cities. [ABSTRACT FROM AUTHOR]

This study aims to investigate spatial and temporal dynamics and relationship between air temperature and five air humidity parameters (relative humidity, water vapor pressure, absolute humidity, specific humidity, and vapor pressure deficit) in Novi Sad, Serbia, based on two-year data (December 2015–December 2017). The analysis includes different urban areas of Novi Sad, which are delineated in five built (urban) types of local climate zones (LCZ) (LCZ 2, LCZ 5, LCZ 6, LCZ 8, and LCZ 9), and one land cover (natural) local climate zone (LCZ A) located outside the urban area. Temporal analysis included annual, seasonal, and monthly dynamics of air temperature and air humidity parameters, as well as their patterns during the extreme periods (heat and cold wave). The results showed that urban dry island (UDI) occurs in densely urbanized LCZ 2 from February to October, unlike other urban LCZs. The analysis of the air humidity dynamics during the heat wave shows that UDI intensity is most pronounced during the daytime, but also in the evening (approximately until midnight) in LCZ 2. However, lower UDI intensity is observed in the afternoon, in other urban LCZs (LCZ 6, LCZ 8, and LCZ 9) and occasionally in the later afternoon in LCZ 5. Regression analysis confirms the relationship between air temperature and each of the analyzed air humidity parameters. [ABSTRACT FROM AUTHOR]

Various micro-scale models for comparing alternative design concepts have been developed in recent decades. The objective of this study is to provide an overview of current user-friendly micro-climate models. In the results, a vast majority of models identified were excluded from the review because the models were not micro-scale, lacking a user-interface, or were not available. In total, eight models met the seven-point inclusion criteria. These models were ADMS Temperature and Humidity model, advanced SkyHelios model, ANSYS FLUENT, ENVI-met, RayMan, SOLWEIG, TownScope, and UMEP. These models differ in their complexity and their widespread use in the scientific community, ranging from very few to thousands of citations. Most of these models simulate air temperature, global radiation, and mean radiant temperature, which helps to evaluate outdoor thermal comfort in cities. All of these models offer a linkage to CAD or GIS software and user support systems at various levels, which facilitates a smooth integration to planning and design. We detected that all models have been evaluated against observations. A wider model comparison, however, has only been performed for fewer models. With this review, we aim to support the finding of a reliable tool, which is fit for the specific purpose. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In the light of climate change and burgeoning urbanization, heat loads in urban areas have emerged as serious issues, affecting the well-being of the population and the environment. In response to a pressing need for more standardised and communicable research into urban climate, the concept of local climate zones (LCZs) has been created. This concept aims to define the morphological types of (urban) surface with respect to the formation of local climatic conditions, largely thermal. This systematic review paper analyses studies that have applied the concept of LCZs to European urban areas. The methodology utilized pre-determined keywords and five steps of literature selection. A total of 91 studies were found eligible for analysis. The results show that the concept of LCZs has been increasingly employed and become well established in European urban climate research. Dozens of measurements, satellite observations, and modelling outcomes have demonstrated the characteristic thermal responses of LCZs in European cities. However, a substantial number of the studies have concentrated on the methodological development of the classification process, generating a degree of inconsistency in the delineation of LCZs. Recent trends indicate an increasing prevalence of the accessible remote-sensing based approach over accurate GIS-based methods in the delineation of LCZs. In this context, applications of the concept in fine-scale modelling appear limited. Nevertheless, the concept of the LCZ has proven appropriate and valuable to the provision of metadata for urban stations, (surface) urban heat island analysis, and the assessment of outdoor thermal comfort and heat risk. Any further development of LCZ mapping appears to require a standardised objective approach that may be globally applicable. [ABSTRACT FROM AUTHOR]

An urban environment defines a specific micro-climate which directly affects the quality of life in urbanized areas and often has a negative impact on urban populations. Phenomena like urban heat and surface heat islands are direct products of an urban lifestyle. Urban meteorological networks (UMNs) are a tool that can help to better understand and analyze the current situation and make the right decisions about future urban development. Deployed to monitor and record different objects and their states inside urban areas, UMNs build a long-term meteorological data time series database. The most commonly used systems for achieving this goal include wireless sensor networks (WSNs). This paper presents a combined experience in deploying three different WSN systems. During seven years of research in this field, the authors have recognized the importance of data reliability in data acquisition. More importantly, due to the lack of research addressing the reliability of the data received from WSNs by the core segment of the server (processes used in receiving, validating, parsing, and storing data into a database instance), the received data are used in scientific studies without questioning their reliability. To determine the possibility of shifting information provided by the data measured from sensor networks before it is stored in a desired form of database, this paper proposes a highly reliable socket server model. The model is built with high reliability and performance in mind and it includes three major processes, which use a combination of signals and control messages to pass information about their states. A case study is performed using high-end hardware, running a Linux operating system stressed to its limits. Repetition testing revealed inconsistency in the information provided by the operating system to the application layer, which could lead to the loss of information about short-term and rarely occurring monitored objects. The results lead to the conclusion that there is a clear need for a higher level of data reliability in the process of data acquisition by UMNs. The proposed socket server should fill this gap within the server's core segment. [ABSTRACT FROM AUTHOR]