983 resultados para Urban heat island


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Biophilic urbanism, or urban design that reflects humanity’s innate need for nature, stands to make significant contributions to a range of national, state and local government policies related to climate change mitigation and adaptation, by investigating ways in which nature can be integrated into, around and on top of buildings. Potential benefits of such design include reducing the heat island effect, reducing energy consumption for thermal control, enhancing urban biodiversity, improving well being and productivity, improving water cycle management, and assisting in the response to growing needs for densification and revitalisation of cities. This report will give an overview of the concept of biophilia and consider enablers and disablers to its application to urban planning and design. The paper will present findings from stakeholder engagement and a series of detailed case studies, related to a consideration of the economics of the use of biophilic elements (direct and indirect).

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As the climate warms, heat waves (HW) are projected to be more intense and to last longer, with serious implications for public health. Urban residents face higher health risks because urban heat islands (UHIs) exacerbate HW conditions. One strategy to mitigate negative impacts of urban thermal stress is the installation of green roofs (GRs) given their evaporative cooling effect. However, the effectiveness of GRs and the mechanisms by which they have an effect at the scale of entire cities are still largely unknown. The Greater Beijing Region (GBR) is modeled for a HW scenario with the Weather Research and Forecasting (WRF) model coupled with a state-of-the-art urban canopy model (PUCM) to examine the effectiveness of GRs. The results suggest GR would decrease near-surface air temperature (ΔT2max = 2.5 K) and wind speed (ΔUV10max = 1.0 m s-1) but increase atmospheric humidity (ΔQ2max = 1.3 g kg-1). GRs are simulated to lessen the overall thermal stress as indicated by apparent temperature (ΔAT2max = 1.7 °C). The modifications by GRs scale almost linearly with the fraction of the surface they cover. Investigation of the surface-atmosphere interactions indicate that GRs with plentiful soil moisture dissipate more of the surface energy as latent heat flux and subsequently inhibit the development of the daytime planetary boundary layer (PBL). This causes the atmospheric heating through entrainment at the PBL top to be decreased. Additionally, urban GRs modify regional circulation regimes leading to decreased advective heating under HW.

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Large conurbations are a significant source of the anthropogenic pollution and demographic differences between cities that result in a different pollution burden. The metropolitan area of Sao Paulo (MASP, population 20 million) accounts for one fifth of the Brazilian vehicular fleet. A feature of MASP is the amount of ethanol used by the vehicular fleet, known to exacerbate air quality. The study describes the diurnal behaviour of the submicron aerosol and relies on total particle number concentration, particle number size distribution, light scattering and light absorption measurements. Modelled planetary boundary layer (PBL) depth and air mass movement data were used to aid the interpretation. During morning rush-hour, stagnant air and a shallow PBL height favour the accumulation of aerosol pollution. During clear-sky conditions, there was a wind shift towards the edge of the city indicating a heat island effect with implications on particulate pollution levels at the site. The median total particle number concentration for the submicron aerosol typically varied in the range 1.6 x 10(4)-3.2 x 10(4) cm(-3) frequently exceeding 4 x 10(4) cm-3 during the day. During weekdays, nucleation-mode particles are responsible for most of the particles by numbers. The highest concentrations of total particle number concentrations and black carbon (BC) were observed on Fridays. Median diurnal values for light absorption and light scattering (at 637 nm wavelength) varied in the range 12-33 Mm(-1) and 21-64 Mm(-1), respectively. The former one is equal to 1.8-5.0 mu g m(-3) of BC. The growth of the PBL, from the morning rush-hour until noon, is consistent with the diurnal cycle of BC mass concentrations. Weekday hourly median single-scattering albedo (omega(0)) varied in the range 0.59-0.76. Overall, this suggests a top of atmosphere (TOA) warming effect. However, considering the low surface reflectance of urban areas, for the given range of omega(0), the TOA radiative forcing can be either positive or negative for the sources within the MASP. On the average, weekend omega(0) values were 0.074 higher than during weekdays. During 11% of the days, new particle formation (NPF) events occurred. The analysed events growth rates ranged between 9 and 25 nm h(-1). Sulphuric acid proxy concentrations calculated for the site were less than 5% of the concentration needed to explain the observed growth. Thus, other vapours are likely contributors to the observed growth.

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The number of hot days is increasing in many parts of the world because of the heat island phenomenon and global climate change. High air temperature greatly affects human thermal comfort and public health, particularly in urban areas. Therefore, the challenging task of, urban designers and urban planners in accommodating the increasing population is to make cities with the least level of vulnerability to future climate change. Interest in transferring urban climatic knowledge into urban planning practices, and developing mitigation strategies to adapt to climate change, has been increased in recent years. The use of vegetation and appropriate urban geometry are shown very promising in mitigating the adverse effects of heat island and providing a better pedestrian thermal comfort. This article reviews studies on pedestrian level urban greening and geometry in improving thermal comfort in cities. Such strategies can be applied at the preliminary stages of urban planning and thus directly affect the microclimate. The analyzed data include simulation and field measurement studies. The discussion of this research clearly reflects how urban design guidelines can be applied to enhance outdoor thermal comfort and minimize the heat island effect. This study is helpful in controlling the consequences of city design from the early design stage.

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Without the virtually free services of nature like clean air and water, humans would not last long. Natural systems can be incorporated in existing urban structures or spaces to add public amenity, mitigate the heat island effect, reduce pollution, add oxygen, and ensure water, electricity and food security in urban areas. Th ere are many eco-solutions that could radically reduce resource consumption and pollution and even provide surplus ecosystem services in the built environment at little or no operational cost, if adequately supported by design. Th is paper is the fi rst of a two part paper that explains what eco-services are, then provides examples of how design can generate natural as well as social capital. Using examples of actual and notional solutions, both papers set out to challenge designers to ‘think again’, and invent ways of creating net positive environmental gains through built environment design.

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Without the virtually free services of nature like clean air and water, humans would not last long. Natural systems can be incorporated in existing urban structures or spaces to add public amenity, mitigate the heat island eff ect, reduce pollution, add oxygen, and ensure water, electricity and food security in urban areas. Th ere are many eco-solutions that could radically reduce resource consumption and pollution and even provide surplus ecosystem services in the built environment at little or no operational cost, if adequately supported by design. Th is is the second part of a two part paper that explains what eco-services are, then provides examples of how design can generate natural as well as social capital. Using examples of actual and notional solutions, both papers set out to challenge designers to ‘think again’, and invent ways of creating net positive environmental gains through built environment design.

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This review article discusses form-based planning an din details analise the following books: Stepehn Marshall (2012) Urban Coding and Planning (Routledge, New York, USA, 272pp. pISBN 1135689202). Emily Talen (2012) City Rules: How Regulations Affects Urban Form (Island Press, Washington DC, USA, 254 pp. ISBN 9781597266925). Richard Tomlinson (2012) Australia’s Unintended Cities: the Impact of Housing on Urban Development (CSIRO Publishing, Collingwood, Australia, 194pp. ISBN 9780643103771). The history of the city has been written and rewritten many times: the seminal works of Benevolo (1980) and Mumford (1989) reconstruct how settlements, particularly their urban form, have changed over centuries. Rowe and Koetter (1978), Kostof (1991, 1992), Krier (2003), and Rossi and Eisenmann (1982) address instead the components that shape the urban environment: the architect can aggregate and manipulate squares, streets, parks and public buildings to control urban design. Generally these studies aim to reveal the secret of the traditional city in contraposition to the contemporary townscape characterized by planning and zoning, which are generally regarded as problematic and sterile (Woodward, 2013). The ‘secret rules’ that have shaped our cities have a bearing on the relationship of spaces, mixed uses, public environments and walkability (Walters, 2011)...

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Biophilic urbanism, or urban design which refl ects human’s innate need for nature in and around and on top of our buildings, stands to make signifi cant contributions to a range of national, state and local government policies related to climate change mitigation and adaptation. Potential benefi ts include reducing the heat island effect, reducing energy consumption for thermal control, enhancing urban biodiversity, improving well being and productivity, improving water cycle management, and assisting in the response to growing needs for densifi cation and revitalisation of cities. This discussion paper will give an overview of the concept of biophilia and consider enablers and disablers to its application to urban planning and design. The paper will present findings from stakeholder engagement related to a consideration of the economics of the use of biophilic elements (direct and indirect). The paper outlines eight strategic areas being considered in the project, including how a ‘daily minimum dose’ of nature can be received through biophilic elements, and how planning and policy can underpin effective biophilic urbanism.

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Cette recherche s’inscrit dans le cadre du programme interdisciplinaire de recherche Ignis Mutat Res et vise à éclairer l’univers de l’architecture sur la capacité des toits à amener des solutions efficaces aux problématiques environnementales dans un contexte urbain dense et à forte consommation d'énergie. La volonté de réduire l’empreinte écologique des villes est aujourd’hui bien présente dans le monde de la recherche architecturale et urbaine, ayant ainsi fait preuve de son importance. Pourtant, la réduction de l’empreinte écologique des villes serait une approche globale difficile à quantifier économiquement. Le manque de méthodologie standardisée fait en sorte que les travaux sur le sujet empruntent des démarches qui ne dépassent pas l’étape exploratoire. Dans ce contexte, le mémoire porte sur l’élaboration d’un dispositif numérique d’évaluation des potentialités des toits horizontaux comme un outil d’aide à la décision pour les interventions urbaines visant à réduire l’empreinte écologique des villes, en utilisant le cas de Montréal. Ce type de toit est abordé comme un territoire d’investigation en contribution aux préoccupations reliées à la gestion de l’eau et à l’atténuation des îlots de chaleur. Plus précisément, cette recherche porte sur trois secteurs de l'île de Montréal. Ces échantillons correspondent à deux types de formes urbaines (résidentielle versus commerciale ou industrielle) et sont décortiqués dans le but d’identifier les déséquilibres entre les espaces naturels, faisant référence aux espaces verts (jardins, parcs et canopées) et les étendues minérales occasionnées par l'urbanisation. Ces rapports exprimés en superficies démontrent que l’étendue des toits est assez considérable pour compenser le manque d’espaces naturels en ville. La végétalisation des toits à l’échelle d’un secteur pourrait donc atténuer considérablement les problèmes environnementaux liés aux îlots de chaleur et à la gestion du ruissellement des eaux de pluie. La stratégie consistant à explorer l'hypothèse des 50 % de naturel versus 50 % de minéral pourrait contribuer grandement à l’autonomisation des villes et à la diminution de leurs dépendances vis-à-vis des ressources fossiles.

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O Homem tem privilegiado a vida no meio urbano, em detrimento do rural, por mais oportunidade de emprego e melhores condições de vida. As cidades cresceram de forma acelerada, sobretudo depois da Revolução Industrial do século XVIII, crescimento sem controlo, repercutindo-se num desajustado planeamento urbano, ambiental, humano, social e económico. De uma forma, as paisagens verdes e naturais, foram substituídas por densas manchas cinzentas de construção, criando afastamento crescente do Homem com a Natureza. Os Jardins Verticais poderão ter um papel fundamental revestindo de forma verde e natural as fachadas dos edifícios, numa tentativa de colmatar o afastamento entre ambos. Para além destes aspectos, os Jardins Verticais proporcionam inúmeras vantagens para o edifício, de que se destacam a eficiência energética e acústica, a protecção da estrutura do edificado ou a melhoria da qualidade do ar interior. Estes também importantes para a envolvente, como na redução do efeito ilha de calor, no aumento da biodiversidade, na melhoria da qualidade do ar exterior, mas sobretudo porque proporcionam ao Homem uma sensação de saúde e conforto, exclusivo da Natureza. Tendo em conta o estado de degradação do edificado nas grandes cidades, e tomando como exemplo particular a cidade do Porto, o recurso aos Jardins Verticais poderá ser uma solução viável para a reabilitação urbana, mudando a imagem de degradação, propondo uma imagem mais “verde” e contribuindo para o nível de sustentabilidade. Partindo deste pressuposto, propõe-se como aplicação do conhecimento adquirido no estudo desenvolvido e aqui apresentado, o recurso a Jardins Verticais como estratégia de reabilitação de edifícios da cidade do Porto. Inspirado na técnica e mestria de Patrick Blanc, resultou um “pormenor-tipo”, como base para a aplicação de Jardins Verticais no edificado social da cidade, experimentado em 10 estudos práticos, tirando-se partido das vantagens supra-mencionadas.

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To bridge the gaps between traditional mesoscale modelling and microscale modelling, the National Center for Atmospheric Research, in collaboration with other agencies and research groups, has developed an integrated urban modelling system coupled to the weather research and forecasting (WRF) model as a community tool to address urban environmental issues. The core of this WRF/urban modelling system consists of the following: (1) three methods with different degrees of freedom to parameterize urban surface processes, ranging from a simple bulk parameterization to a sophisticated multi-layer urban canopy model with an indoor–outdoor exchange sub-model that directly interacts with the atmospheric boundary layer, (2) coupling to fine-scale computational fluid dynamic Reynolds-averaged Navier–Stokes and Large-Eddy simulation models for transport and dispersion (T&D) applications, (3) procedures to incorporate high-resolution urban land use, building morphology, and anthropogenic heating data using the National Urban Database and Access Portal Tool (NUDAPT), and (4) an urbanized high-resolution land data assimilation system. This paper provides an overview of this modelling system; addresses the daunting challenges of initializing the coupled WRF/urban model and of specifying the potentially vast number of parameters required to execute the WRF/urban model; explores the model sensitivity to these urban parameters; and evaluates the ability of WRF/urban to capture urban heat islands, complex boundary-layer structures aloft, and urban plume T&D for several major metropolitan regions. Recent applications of this modelling system illustrate its promising utility, as a regional climate-modelling tool, to investigate impacts of future urbanization on regional meteorological conditions and on air quality under future climate change scenarios. Copyright © 2010 Royal Meteorological Society

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Existing urban meteorological networks have an important role to play as test beds for inexpensive and more sustainable measurement techniques that are now becoming possible in our increasingly smart cities. The Birmingham Urban Climate Laboratory (BUCL) is a near-real-time, high-resolution urban meteorological network (UMN) of automatic weather stations and inexpensive, nonstandard air temperature sensors. The network has recently been implemented with an initial focus on monitoring urban heat, infrastructure, and health applications. A number of UMNs exist worldwide; however, BUCL is novel in its density, the low-cost nature of the sensors, and the use of proprietary Wi-Fi networks. This paper provides an overview of the logistical aspects of implementing a UMN test bed at such a density, including selecting appropriate urban sites; testing and calibrating low-cost, nonstandard equipment; implementing strict quality-assurance/quality-control mechanisms (including metadata); and utilizing preexisting Wi-Fi networks to transmit data. Also included are visualizations of data collected by the network, including data from the July 2013 U.K. heatwave as well as highlighting potential applications. The paper is an open invitation to use the facility as a test bed for evaluating models and/or other nonstandard observation techniques such as those generated via crowdsourcing techniques.

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This study aims to examine the thermal structure of the urban climate based on the interpretation of the satellite Landsat 7 (thermal channel) and measures for the area. It identifies how the production of urban climate develops based on an analysis of the structure of space forms and characteristics of land use and constructive materials in the generation of heat islands and their implications in environmental comfort in a tropical climate medium size city at Brazil. To check intra-urban air temperature, measures were carried out in mobile transects in the North-South and East-West routes. Thermal Channel data of Landsat-7, were converted to surface values. The results showed that the pattern of urbanization and characteristics of land use are responsible for the distribution of temperature generating heat islands in downtown and popular densely built neighborhoods. In those cases the highest indexes of social segregation added to higher temperature also provokes elevation in the number of illnesses and morbidity cases, mostly of respiratory diseases.

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This study is aimed to analyze the thermal comfort in different areas in the city of São Paulo. Two different areas were selected, a densely built (Consolação district) and the other was Fontes do Ipiranga State Park (FISP), an area with only a few buildings and reduced impermeability. A micro-climatic ENVImet was used to simulate the interaction surface-atmosphere in the urban environment. The model resolution is between 0.5 and 10m. This model was developed by Bruse and Fleer (1998) and Bruse (2004). Through the thermal comfort index PMV (predicted mean vote) and MRT (mean radiant temperature) provided by the model, it revealed that the State Park displays PMV values close to comfortable compared to the other studied area. The analysis of thermal comfort index and the Wind flow showed the influence of high buildings in the local climatic environment.

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Pós-graduação em Geografia - IGCE