Sustainability of compact cities: the SOS_UrbanLab activity

Urban development is facing new challenges to allow the evolution of the environment, in accordance to sustainability principles. In this context, decision makers have to answer to three main issues: how to intervene on the existing compact cities? How to combine and develop interventions on different scales? How to move from requalification to regeneration? The SOS_UrbanLab (Engineering Laboratory for Construction and Environmental Sustainability) researches, starting from a multi-scale analysis, propose a set of eco-friendly solutions to support the potential and capability of territories, integrating their benefits to reach a full sustainable approach

On the Calculation of Urban Morphological Parameters Using GIS. An Application to Italian Cities

The identification of parameters that can quantitatively describe the different characteristics of urban morphology is fundamental to studying urban ventilation and microclimate at the local level and developing parameterizations of the dynamic effect of an urban area in mesoscale models. This paper proposes a methodology to calculate four morphological parameters, namely mean height, aspect ratio, sky view factor, and plan area ratio, of five cities located in southern (Bari and Lecce), central (Naples and Rome), and northern (Milan) Italy. The calculation is performed using the Geographical Information System (GIS), starting from morphological and land use data collected and analyzed in shapefiles. The proposed methodology, which can be replicated in other cities, also presents in detail the procedure followed to properly build input data to calculate the sky view factor using the UMEP GIS tool. The results show a gradual increase in the plan area index, λp, and mean building height, (Formula presented.), moving from the south to the north of Italy. Maximum values of λp and (Formula presented.) are obtained in the regions of Milan, Rome, and Naples, where the highest spatially-averaged values are also found, i.e., λp = 0.22, (Formula presented.) = 10.9 m in Milan; λp = 0.19, (Formula presented.) = 12.7 m in Rome; λp = 0.20, (Formula presented.) = 12 m in Naples. Furthermore, for all the cities investigated, areas characterized by the Corine Land Cover class as “continuous urban fabric” are those with medium sky view factor SVF values (around 0.6–0.7) and λp values (around 0.3) typical of intermediate/compact cities. The methodology employed here for calculating morphological parameters using GIS proves to be replicable in different urban contexts. This opens to a better classification of cities in local climate zones (LCZ), as shown for the Lecce region, useful for urban heat island (UHI) studies and to the development of parameterizations of the urban effects in global and regional climate models

Urban ventilation and the compact Mediterranean city numerical analysis of the dynamic relationships between density, morphology, and wind flow

Combining urbanization and climate change provides new and complex challenges to our cities since they represent a vulnerable element at the center of human life. Cities have been regarded as the emblem of scientific and technological progress, health, and wealth for centuries by humankind. They have gradually attracted the majority of the world population and economic activities. In this process, cities increased in number, size, and density, leading to gradual and inexorable environmental and social degradation. Consequently, the challenge towards more sustainable and resilient built environments has become urgent, especially in existing cities. In this framework, investigations of wind flow in the urban environment are of primary importance. They involve various topics and associated processes, such as human health and comfort, energy consumption and production, durability and robustness of materials, buildings, and infrastructures. Weak wind conditions, often experienced in compact urban areas, can be responsible for low air quality, hence higher potentially hazardous air pollution levels, and higher temperatures, thus increased amplification of heatwaves and human thermal stress. These phenomena cause augmented morbidity, mortality, and energy demand for air cooling and purification. The detrimental effects of air pollution and heat stress on human health and comfort may be mitigated by exploiting urban ventilation. Urban ventilation represents the capacity of a built area for introducing fresh air within its tissue and diluting pollutants and heat within its canyons. The phenomenon is closely related to urban morphology, i.e., the form and the structure of the urban area, the physical characteristics of the buildings, and their mutual arrangement. Conversely, urban morphology can be an effective tool in renewal plans for improving urban ventilation in urban areas. For this purpose, detailed investigations of the impact of actual urban morphologies on urban ventilation are fundamental and represent an essential step towards more sustainable and resilient cities, especially in the Mediterranean area, where a continuous increase in the mean air temperature can already be observed. However, given the complexity of the phenomena in play, the majority of these studies used simplified models of actual urban areas, i.e., arrangements of generic building geometries forming idealized urban structures. Albeit useful, these simplified models may not reproduce the complexity of the built environment. In this regard, the main objective of the present research is to identify and validate a methodology for analyzing the effects of urban density and morphology on urban ventilation performance in actual urban areas. The research is structured in three main phases. The first phase involves describing and quantifying the physical structure of urban areas. The second phase covers the investigation of wind flows at the relevant observation scale for the selected case study. The final phase regards the correlation of the results of the analyses performed during the previous two stages. In the first stage, through an extensive literature review, indices used by practitioners and city planners are selected to describe and quantify the densities and morphologies of different urban tissues. The district scale is used as the operational scale to perform morphological analyses because it is suitable to describe the morphological characteristics of urban areas. The Tuscolano-Don Bosco district, an area in the Southeast of Rome, is selected as the case study. The district presents morpho-typological features typical of compact cities in the Mediterranean basin. Morphological analyses are conducted for the selected area using GIS software, and several scripts and algorithms have been used to combine the raw data to calculate the morphological parameters. In the second stage, appropriate tools, techniques, and indicators for investigating wind flows and assessing urban ventilation performance at the district scale in actual urban areas are selected. Then, 3D steady-state RANS simulations are performed for 12 different wind directions to investigate the impact of different urban morphologies on wind flows and urban ventilation in the selected area. The validation of the computational setting is performed using experimental data from wind-tunnel measurements found in literature and conducted for an idealized case study with physical features similar to the actual case study, applying the so-called sub-configuration approach. The results are presented in terms of non-dimensional mean wind velocity and local age of air, i.e., the time a particle of external fresh air spends replacing a particle of the pollutant in a specific location within the area of interest. The abovementioned parameters and their derivatives are employed in the research as key performance indicators for urban ventilation. In the third stage, the wind environment in the entire case study is described and analyzed. The non-dimensional mean wind velocity calculated at two different heights is correlated to the selected morphological parameters to provide linear, easy-to-use models for highlighting areas potentially vulnerable to poor air conditions without running computationally expensive simulations. Finally, the key performance indicators are used to assess the effectiveness of the different morphologies within the case study in enhancing urban ventilation. The results show that, in a compact urban area, a drastic reduction in the mean wind velocity, up to 60%, can be experienced at the pedestrian level with a consequent worsening of thermal comfort conditions and air quality. The mean wind velocity reduction is dependent on the urban density and increases monotonically with increases in the morphological parameters. Moreover, the linear models between urban ventilation indicators and morphological parameters show remarkable correlations: coefficients of determination up to 89%. Furthermore, results demonstrate that specific morphologies depending on the wind direction can determine locally pronounced increases in the mean wind velocity, up to 135%, and enhance urban ventilation. The research results confirm the potential of urban morphology in enhancing urban ventilation and the need for approaching regeneration plans according to a climate-sensitive/climate-aware way since sustainability and resilience are the ultimate goals. This research contributes to establishing a knowledge base of the wind environment in compact cities and developing guidelines for prioritizing regeneration plans in existing urban areas. This work represents a further step to integrate different disciplines to ease the management of the urban environment complexity. The research outcomes are of interest to stakeholders, practitioners, policymakers, and researchers

La ventilazione urbana nella città compatta mediterranea. Una metodologia operativa multidisciplinare per migliorare la sostenibilità e la resilienza delle aree urbane

L’urbanizzazione e i cambiamenti climatici forniscono nuove e più complesse sfide alla gestione delle nostre città. Al fine di rendere le aree urbane più sostenibili e resilienti, bisogna analizzare le relazioni che si instaurano tra la morfologia urbana e il contesto ambientale, sociale ed economico e quantificare gli effetti di queste relazioni sulla salute e il benessere dell’uomo secondo principi prestazionali. In questo contesto, l’interazione vento – morfologia urbana è un argomento fondamentale da esaminare in ambiente urbano perché coinvolge una grande varietà di fenomeni che a diversa scala hanno ripercussioni più o meno dirette sulla vita, sulla salute e sul benessere dell’uomo. Sebbene ventilazione urbana e qualità dell’aria siano due concetti fondamentali da trattare in studi che riguardano la salute, la resilienza e la sostenibilità delle città, ricerche che mirano alla quantificazione degli effetti della morfologia sulla ventilazione in aree urbane compatte esistenti sono rare a causa della complessità del fenomeno oggetto di studio e alla specializzazione richiesta dagli strumenti a disposizione per la sua modellazione ed analisi. La ricerca che si presenta in questo articolo propone una metodologia multidisciplinare operativa e di indagine che correli parametri morfologici a prestazioni dei tessuti urbani valutati in termini di ventilazione urbana e qualità dell’aria analizzati per mezzo di simulazioni fluidodinamiche computazionali. In questa ottica, lo studio quantitativo della morfologia urbana e l’uso della densità si dimostrano molto promettenti ed offrono nuove opportunità di approfondimento aprendo diversi spunti per investigazioni multidisciplinari. Le simulazioni fluidodinamiche si rivelano un adeguato strumento operativo e di indagine alla scala del quartier

Urban Ventilation in the Compact City: A Critical Review and a Multidisciplinary Methodology for Improving Sustainability and Resilience in Urban Areas

In the last decades, a tendency towards urban tissue densification has been observed to counteract the urban sprawl. Densification may be achieved through more compact built areas, preferring the vertical to the horizontal development of buildings but avoiding bulky high-rise building blocks. This strategy significantly affects several aspects of the microclimate and produces direct and indirect effects on human health and well-being. In this regard, air pollution and heat stress constitute two increasing threats to human health and well-being that need to be faced immediately. The involved phenomena are various, intertwined, and may lead to conflicting results. Hence, regenerating existing, well-structured, and stratified urban areas by densification is not an easy challenge. Urban ventilation may favor the mitigation of detrimental effects of air pollution and heat stress on human life. Therefore, a multidisciplinary methodology is presented for embedding urban ventilation performance evaluation into urban management and planning processes. The scope is to propose a framework for urban renewal plans that is citizens-centered and aims at improving their health and well-being in existing urban areas. The methodology builds upon the performance-based approach and is supported by the conceptual framework and the literature reviews provided through the paper

Urban Ventilation in the Compact City: A Critical Review and a Multidisciplinary Methodology for Improving Sustainability and Resilience in Urban Areas

In the last decades, a tendency towards urban tissue densification has been observed to counteract the urban sprawl. Densification may be achieved through more compact built areas, preferring the vertical to the horizontal development of buildings but avoiding bulky high‐rise building blocks. This strategy significantly affects several aspects of the microclimate and produces direct and indirect effects on human health and well‐being. In this regard, air pollution and heat stress constitute two increasing threats to human health and well‐being that need to be faced immediately. The involved phenomena are various, intertwined, and may lead to conflicting results. Hence, regenerating existing, well‐structured, and stratified urban areas by densification is not an easy challenge. Urban ventilation may favor the mitigation of detrimental effects of air pollution and heat stress on human life. Therefore, a multidisciplinary methodology is presented for embedding urban ventilation performance evaluation into urban management and planning processes. The scope is to propose a framework for urban renewal plans that is citizens‐centered and aims at improving their health and well‐being in existing urban areas. The methodology builds upon the performancebased approach and is supported by the conceptual framework and the literature reviews provided through the paper

Rigenerazione urbana dell’ex fabbrica di saponi Mira Lanza a Roma: un nuovo scenario di parco resiliente

Il carattere naturalistico dell’area, esaltato dalla vicinanza con il corridoio fluviale romano, si fonde con quello industriale, costituito dalla presenza dell’ex stabilimento della Mira Lanza. Qui l’avanzato degrado ha trasformato i manufatti in veri e propri ruderi di archeologia industriale ed il sito, altamente inquinato, giace in prossimità di una risorsa idrica di grande rilievo, quale il fiume Tevere. Si propone, così, un intervento di fitorimedio in situ a lungo termine; una tecnologia che prevede l’impiego di piante per la bonifica del suolo. Contestualmente, si progetta la realizzazione di un parco urbano, con percorsi attrezzati sopraelevati, che, partendo dalla quota posta ai margini della Mira Lanza, viaggiano, sospesi da terra, tra ruderi industriali e verde. La ricerca proposta, pertanto ha per oggetto la realizzazione di un Parco Resiliente, che sappia adattarsi al contesto specifico e trasformi per la Città tutta le problematiche in opportunità

Rigenerazione dei fabbricati viaggiatori della stazione ferroviaria e riqualificazione dell’ex stabilimento delle Fornaci Briziarelli di San Gemini // Regeneration of the passenger buildings of the railway station and redevelopment of the former factory Fornaci Briziarelli in San Gemini

Il Piano Nazionale di Ripresa e Resilienza Umbria 2021-2026, approvato nell’aprile 2021 dalla Giunta Regionale, riconosce nel turismo sostenibile «un potere attivante sull’economia», tanto da riconoscere la «valorizzazione delle aree interne e dei borghi della regione». La presenza di borghi storici sarà la base per innovare la concezione della mobilità in una chiave aggiornata e impostata sulla rigenerazione turistica del tracciato ferroviario della ex Ferrovia Centrale Umbra. In base al PNRR ci si propone di riconvertire e trasformare i fabbricati viaggiatori della stazione di San Gemini, per ospitare le attrezzature di supporto ai turisti e di bike sharing e l’ex stabilimento Fornaci Briziarelli per la produzione di mattoni, che recuperato, diverrà l’elemento principale dell’intera area. Il fabbricato appartamenti, che ospitava gli operai, avrà la funzione di hotel/bed and breakfast; qui potranno soggiornare i turisti in visita alle bellezze del territorio di San Gemini