L'Ilot de Chaleur Urbain (ICU) est l'un des phénomènes du changement climatique les plus documentés. Il est le résultat de températures plus élevées dans le centre des villes que dans leurs banlieues ou les zones rurales alentour et peut avoir des conséquences néfastes sur les habitants des villes, notamment au niveau de la qualité de l'air, la consommation d'énergie, la santé publique et même le taux de mortalité. À Beyrouth, capitale du Liban, la littérature scientifique existante dénote un déficit de recherche sur ce sujet. L’objectif de cette thèse est donc d'étudier l'intensité de l'ICU à Beyrouth, d'identifier les mesures les plus appropriées susceptibles d'en alléger les effets d'un point de vue technique, d'en évaluer les conséquences sur les politiques d'urbanisme et de faire des propositions pour la planification urbaine et la conception des bâtiments à Beyrouth. Dans cette thèse, l'ICU à Beyrouth a été étudié à l'aide du modèle Town Energy Balance (TEB), outil de modélisation servant à calculer les échanges d'énergie et d'eau entre les villes et l'atmosphère, développé par Météo France (Masson, 2000). TEB est inclus dans le système de modélisation des surfaces continentales SURFEX. SURFEX est une contraction de « Surface Externalisée » et c'est un code qui modélise les processus d'échange d'énergie entre l'atmosphère et les surfaces urbaines. Des simulations ont été effectuées à Beyrouth durant une journée, en hiver, le 1er janvier de 00:00 UTC (soit 02:00 heure locale) à 23:00 UTC et une journée, en été, le 1er juillet de 00:00 UTC à 23:00 UTC à des intervalles d'une heure. En été, des écarts significatifs allant jusqu'à 6°C ont été enregistrés pour les températures de canyon. Typiquement, les températures les plus élevées ont été enregistrées dans les zones à forte densité de construction où la part de surfaces travaillées par l'homme est la plus grande et où on a mesuré les albédos les plus bas (généralement 0.2). En hiver, les écarts de température ont été moins significatifs avec un différentiel de 1°C entre les zones à forte densité de construction et les espaces naturels. On en a déduit que les zones avec une grande proportion de végétations ont un rôle réfrigérant à Beyrouth. De plus, nous avons mesuré un écart significatif dans la consommation d'énergie pour la climatisation en été dans différentes parties de Beyrouth ; les simulations ont déterminé la demande requise d'énergie à 50 W/m2 dans les quartiers caractérisés par une grande proportion de jardins et jusqu'à 800 W/m2 dans les quartiers à forte densité de construction. En hiver également, les simulations ont montré des écarts importants au niveau de la demande d'énergie pour le chauffage dans différents quartiers de Beyrouth variant de 20 à 300 W/m2. Six scénarios ont été modélisés sur TEB et ils ont indiqué que l'augmentation de la surface des végétations et l'augmentation de l'albédo des toits produisaient les effets de refroidissement les plus notables. Cette thèse a mis en évidence des opportunités pour améliorer les lois de l'Urbanisme et le Code de la Construction au Liban pour une meilleure prise en compte des aspects microclimatiques urbains et recommande la mise en place de stratégies pour le développement d'espaces verts urbains et pour l'optimisation du refroidissement par les toits. Cette thèse a donc contribué à une meilleure compréhension de l'environnement urbain de la ville de Beyrouth et des paramètres urbains pouvant avoir le plus grand impact sur la réduction des effets de l'ICU. Ce faisant, cette étude a préparé le terrain pour des travaux plus poussés en vue de réduire les effets de l'ICU à Beyrouth dans le but de créer un environnement confortable et sain pour ses habitants et pour les générations futures / The urban heat island (UHI) is one of the more commonly documented phenomena of climate change. It is related to higher urban temperatures in the city centers as compared to the surrounding rural or suburban areas and can lead to unpleasant effects on urban dwellers not least of all on air quality, energy consumption levels, human health, and even mortality rates. In Beirut, the capital city of Lebanon, the literature clearly points to a lack of research on this topic. In addition, there is no evidence that there is a systematic transfer of urban climatic knowledge between concerned stakeholders like urban planning and environmental authorities which is cause for concern given the ever-increasing worldwide attention being given to climate change adaptation and mitigation measures and sustainable city developments. The objective of this research is to therefore investigate the intensity of UHI in Beirut, to identify most suitable measures to alleviate the effects of UHI from a technical perspective, to assess the implications on urban planning processes and to accordingly find opportunities for planning and design practices in Beirut. Beirut is a coastal city that sits on a peninsula that extends westward into the Mediterranean Sea. It covers a surface area of about 20 square kilometers, has a population of approximately 500,000 inhabitants, with a very high population density of about 21,000 inhabitants / km2.The UHI in Beirut was investigated using the Town Energy Balance (TEB) urban surface exchange modeling scheme developed by Météo France (Masson, 2000). TEB is included in the SURFEX land-surface modeling system. SURFEX means “surface externalisée” and it is a code that represents the energy exchange processes that occur between the atmosphere and the urban surfaces. Simulations were accordingly run across Beirut using TEB for 1 day during the winter season on 1 January, from 00:00 UTC (equivalent to 2:00AM local standard time) to 23:00 UTC, and 1 day during the summer season on 1 July from 00:00 UTC to 23:00 UTC with one hour time steps or one hour output results. During the summer significant variations of up to 6oC were found for canyon temperatures whereas areas characterized by dense urban fabrics had higher temperatures typically due to the larger fraction of man-made as opposed to natural surfaces and due to the lower albedo values (generally 0.2). During the winter, temperature variations were not as significant, differing by up to 1oC between aforementioned areas across Beirut. Therefore areas with high garden fractions were found to play an important cooling effect in the simulations for Beirut. In addition, a significant variation in cooling energy usage was found during the summer across Beirut where simulations showed energy demands as low as 50 W/m2 in areas characterized by higher garden fractions whereas simulations were much higher, up to 800 W/m2, in areas with dense urban fabrics. In the summer heating energy demands were also significant ranging from as low as 20-300 W/m2 across Beirut. Six scenarios were also run on TEB which showed that increasing the albedo of roofs and the fraction of gardens had the most noteworthy cooling effects. This research found that there are opportunities for improvement of the Urban Planning Law and the Building Code of Lebanon for better consideration of the urban microclimatic issues and recommended emphasis on urban greening strategies and cool roofing strategies. this thesis contributed to a better understanding of the urban environment of the city of Beirut and the respective urban parameters that have the most significant impact on reducing some of the impacts of the urban heat island phenomenon. In doing so, this research has paved the way for further work on reducing the UHI effect in Beirut, with the ultimate aim of creating a comfortable and safe environment for its residents, and future generations

Le GIEC (groupe d’expert Intergouvernemental sur l’Evolution du Climat) dans leur 4 ème rapport souligne que les villes européennes seront impactées par des épisodes caniculaires plus fréquents et plus intenses dû aux modifications climatiques ayant lieu au cours du XXI ème siècle. La ville, espace climatique particulier, sensiblement plus chaud que son espace environnant amplifie le phénomène de l’îlot de chaleur urbain (ICU). Pour la ville de Paris, les îlots de chaleur urbains peuvent dépasser de 8 à 10°C les températures relevées quelques kilomètres plus loin. Cet effet est d’autant plus néfaste lors de période caniculaire comme a connu la France en 2003, 2006, 2010 ou bien même en 2015. La connaissance sur le phénomène de la canicule nécessite de mettre en relation des données autant spatiales que temporelles afin de définir des zones à risques .Pour pouvoir simuler une canicule, le modèle SURFEX-TEB, conçu par Météo-France, CNRS, a été choisi. Il permet d’estimer la température en ville à partir de conditions climatiques des plus hautes atmosphères. Ces prévisions sont importantes notamment en période de canicule où les écarts de température entre la ville et sa banlieue peuvent dépasser 8C°. Le risque caniculaire, induit par les ICU, est complexe à appréhender et à représenter.Pour caractériser, appréhender et représenter la canicule, avec l’aide du modèle SURFEX-TEB, nous avons effectué une assimilation avec des mesures réalisées pendant la canicule de 2015 sur Paris. Cette assimilation met en évidence par exemple les phénomènes d’accumulation et l’impact des configurations des appartements sur les températures intérieures et extérieures. Nos différentes configurations ont permis de confirmer l’importance de considérer les températures intérieures lors de périodes caniculaires.Ce travail de recherche propose donc un éclairage spécifique et technique de la représentation des canicules. Son objectif est une meilleure représentation des canicules et l’estimation de leur dangerosité en fonction de la durée du phénomène, de son intensité et des caractéristiques urbaines et humaines. Des cartes décrivant la canicule et sa dangerosité sont mises en valeur grâce à l’élaboration d’un site web grand public.Les résultats de cette recherche soulèvent une interrogation sur les seuils de canicule. Ils soulignent l’importance d’introduire un seuil de canicule intérieur et démontrent le rôle de la configuration urbaine et en particulier des types d’habitation pour mieux prendre en compte la dangerosité des canicules et espérer mieux atténuer leurs effets / The IPCC (Intergovernmental Panel on Climate Change) in its 4th report underlines that the European cities will be impacted by more frequent and more intense scorching episodes due to the climatic modifications taking place during the XXIth century. Peculiar climatic areas, significantly hotter than their surroundings, cities amplify the phenomenon of the urban heat island (UHI). In the example of Paris, the urban islands of heat can exceed by 8°C to 10°C the temperatures measured a few kilometers away. This effect is all the more fatal as heat wave periods become more and more regular (2003, 2006, 2010, 2015). The knowledge on the heat wave phenomenon requires to put in relation spatial and temporal data so as to define high-risk areas.To be able to simulate a heat wave, the SURFEX-TEB model, designed by Météo-France, and CNRS, was chosen. It allows to estimate the temperature in town from weather conditions of the highest atmospheres. These forecasts are particularly important in heat wave periods where temperature differences between cities and suburban areas can exceed 8°C. The heat wave risk, resulting from the UHI, is complex to both understand and represent.To characterize, understand and represent the heat wave by the means of the SURFEX-TEB model, we made a data fusion with measures realized during the 2015 heat wave in Paris. This assimilation highlights, for instance, the accumulation phenomena and the impact of the apartments configuration on the inside and outside temperatures. Our various configurations allowed to confirm the importance of taking into account the internal temperatures during heat waves periods.This research thus proposes a specific and technical perspective of the heat waves representation. Its objectives are a better representation of heat waves and a sharper estimation of their dangerousness according to the phenomenon duration, its intensity and the urban and human features. Maps describing the heat wave and its dangerousness are highlighted thanks to the elaboration of a public Web site.The results of this research rise an interrogation on the thresholds of heat wave. They underline the importance to introduce an internal threshold of heat wave and demonstrate the role of the urban configuration, particularly the types of house. This should contribute to better take into account the dangerousness of heat waves and to improve the mitigation of their effects

Global warming risks overthrowing the Earth's climate system, which would mean thatmany communities need to be reshaped and adapted to a new climate. The PublicHealth Agency of Sweden has run a project during the years 2017-2019 that aims toincrease society's ability to identify, prevent and manage harmful heat in existingbuildings. The project focuses on covering the occurrence and developing measures toprevent heat stress in both urban outdoor- and indoor environments. The agency has commissioned a GIS method which, based on the buildings' groundcover, aims to identify areas that are at risk of developing harmful temperatures. Themethod is based on first calculating the total land area of the cities in order to be able tocalculate the proportion of the area covered by high vegetation, hardened surfaces,building bodies and low vegetation. Based on this calculation, areas with a highproportion of paved surfaces and building bodies as well as a low proportion of highvegetation have been identified as areas with a higher risk of developing harmfultemperatures. In this essay, the method has been used to identify risk areas in KalmarCounty's largest cities; Kalmar, Västervik and Oskarshamn. High temperatures can be dangerous for all people, but elderly people are highlighted asa particularly vulnerable group as they have a reduced ability to regulate bodytemperature. Therefore the survey of the thesis has been supplemented with data onwhere people over the age of 65 live in relation to the risk areas in order to make furtherpriorities in where the measures are needed the most. The conclusion is that the need for cooling measures in the mapped cities is greatest inthe urban centers, as the high density of urban areas there provides good conditions fordeveloping high temperatures while a large part of the old population live in thesecentral areas. Several industrial areas have been identified as risk areas in all mappedcities, but there the need for cooling measures is less as they are usually located on theoutskirts of the cities and lack residents over 65 years. The exception is the OldIndustrial Area in Kalmar, whose central location and the circular design of Kalmarindicate that high temperatures develop here at night, which can drive the urban heatisland in the city.

En 2003 des mesures au spectromètre IR à Transformée de Fourier (FTIR) ont permis d'identifier et de mesurer les COV émis par la décharge à ciel ouvert de la Gabarre, principale de l'île Guadeloupe, située entre une zone urbaine et une mangrove. Ces COV ont été retrouvés (2004) la nuit dans les cités, justifiant les plaintes des riverains. Dans le cadre de cette thèse, des mesures au spectromètre de masse portatif MS 200 ont validé ces résultats du FTIR. De nouvelles mesures au MS 200 ont été menées dans toute la zone de la décharge. Les cités concernées étant à l'opposé du flux synoptique d'Alizés-Est, les facteurs météorologiques permettant la dispersion et le transport des COV de la décharge vers la zone urbaine ont été recherchés. La diminution nocturne de l'intensité des Alizés au dessus de l'ile peut laisser place à des phénomènes locaux tels les brises. L'idée d'une brise terre-mer a été éliminée. Un maillage autou~ de la décharge (cités et mangrove) avec 8 thermomètres a révélé un îlot de chaleur urbain nocturnegénérant une brise thermique d'environ Ims- I (mesurée et calculée). Avec les radiosondages Météo France et un SODAR installé dans la décharge, une très forte stabilité dans les basses couches atmosphériques de la couche limite nocturne avec une inversion de surface d'environ 120mvv apparait. Ces facteurs expliquent la pollution des cités par les COV de la décharge, Un modèlevGaussien en tenant compte a été validé par les mesures de COV.vCette étude peut être étendue à d'autres décharges à ciel ouvert et à d'autres types de traitement de polluants de décharge. / In 2003, the VOC emissions coming from "La Gabarre", the main open landfill in Guadeloupe, located in-between an urban area and a mangrove, were identified and quantified with a portable FTIR spectrometer. In 2004, COVs found at nighttime in the urban area nearby confirmed why residents complain about. As part of this thesis, portable mass spectrometer MS 200 measurements validated these FTIR figures. New systematic SM measurements have been carried on around the landfill. Since the polluted urban area stands on the opposite way of the East Trade winds synoptic flux, aIl the weather factors likely to scatter and transport the dump COVs were scrutinized. At night, the strength of the Trade winds decreases over Guadeloupe, which may give way to local phenomena such as breezes. The occurrence of land/sea breeze was eliminated. A close surveying surrounding the landfill with 8 thermometers both in the projects and in the mangrove revealed an urban heat island causing thermal breezes of about lms-l (measured and calculated). Using soundings from Meteo France, and a SODAR inside the dump, we found a great stability of the night boundary layer with a surface inversion near 120m. Pollution of the nearby urban area with landfill COVs is elucidatcd by the above factors. A transport Gaussian model is in agreement with COV measurements. This study can be extended to different open landfills and different types of polluting matters processes in dumps

Cities are rapidly expanding, and global warming is intensified in urban environments due to the urban heat island effect. Therefore, urban animals may be particularly susceptible to warming associated with ongoing climate change. Thus, I used a comparative and manipulative approach to test three related hypotheses about the determinants of heat tolerance or critical thermal maximum (CTmax) in urban ants—specifically, that (1) body size, (2) hydration status, and (3) preferred micro-environments influence CTmax. I further tested a fourth hypothesis that native species are particularly physiologically vulnerable in urban environments. I manipulated water access and determined CTmax for 11 species common to cities in California's Central Valley that exhibit nearly 300-fold variation in body mass. Inter- (but not intra-) specific variation in body size influenced CTmax where larger species had higher CTmax. The sensitivity of ants’ CTmax to water availability exhibited species-specific thresholds where short-term water limitation (8 h) reduced CTmax in some species while longer-term water limitation (32 h) was required to reduce CTmax in other species. However, CTmax was not influenced by the preferred foraging temperatures of ants. Further, I did not find support for my fourth hypothesis because native species did not exhibit reduced thermal safety margins, or exhibit CTmax values that were more sensitive to water limitation relative to non-native species. In sum, understanding the links between heat tolerance and water availability will become critically important in an increasingly warm, dry, and urbanized world that may be selecting for smaller (not larger) body size.

No description available.

Buildings account for over 35% of the energy demand in OECD countries, making them a prime target for improvement. (EIA 2011) To help building owners reduce energy usage, ratings systems such as LEED have been developed. A prerequisite for certification is the demonstration of energy efficiency through computer modeling; however, the complex nature of building energy simulations too often leads to errors of up to 30% (Turner and Frankel 2008). One source of significant error can be the assumptions made of environmental conditions, which are often simplified to speed up simulations. To demonstrate the significance of active microclimate modeling, a building energy model combined with a microclimate model has been created in RadTherm, a commercial CAE thermal solver. Simulations are run using Passive House construction in three types of environments, and demonstrate an increase in energy demand over an annual time scale when microclimatic components are included. The increase in demand is less than 1%, however the decrease in radiant heat losses are up to 30%. Using the same methodology with revisions to the building construction and urban geometry, a larger increase in energy demand is expected.

The severity of extreme heat events paired with the urban heat island effect cannot be overstated, as the impacts are substantial and widespread, affecting peak energy demands, transport systems, air and water quality, and most notably causing heat-related illnesses and death. These consequences make evident the importance of reducing heat in urban areas and ensuring that urban populations are safe during extreme heat events. In order to both reduce the urban heat island effect and prepare cities for a hotter future, it is critical to building our understanding of the cities at risk and the relationship between heat and the urban environment. This thesis applies urban morphology theory and remote sensing techniques to explore how urban typologies in Metro Boston perform during an extreme heat event. Included within the thesis is a literature review exploring urban heat methodologies and urban morphology, a desktop review examining a set of cities’ climate action reports, and a remote sensing-based analysis to determine the feasibility of uniting land surface temperature and public weather station data. The desktop review of cities determined that while each city has begun to implement numerous socially driven initiatives and large-scale green infrastructure plans, there is little work incorporating urban form within these strategies. Additionally, while the land surface temperature and weather station maps from the remote sensing analysis were deemed insufficient, several valuable questions and findings arose through the process. The case study analysis of Metro Boston identified three predominant urban forms in the study area and 12 sites were studied in relation to their heat performance in the morning, afternoon, and evening. The heat maps applied were developed through Heat Watch Report, a collaboration between the National Oceanic and Atmospheric Administration, the municipalities of Boston, Brookline, and Cambridge, and CAPA Strategies. The analysis revealed there is a universal change in temperature among all forms throughout the day, with peak temperatures occurring in the late afternoon period. The study also concluded that while temperature between forms was not significant, variation between sites of the same form was observed, with internal vegetation composition (NDVI) and neighboring landcover and urban form becoming key factors in increasing or reducing experienced heat. / Svårighetsgraden av extrema värmehändelser i kombination med stadens värmeöeffekt kan inte överskattas eftersom dessa effekter är betydande och utbredda, vilket påverkar energibehov, transportsystem, luft- och vattenkvalitet och framför allt orsakar värmerelaterade sjukdomar och dödsfall. Dessa konsekvenser visar tydligt vikten av att minska värmen i stadsområden samt se till att stadsbefolkningarna är säkra under extrema värmehändelser. För att både minska stadens värmeöeffekt och förbereda städer för en varmare framtid är det avgörande att fördjupa vår förståelse för städer i riskzon och förhållandet mellan värme och stadsmiljö.  Denna avhandling tillämpar urban morfologiteori och fjärranalys tekniker för att utforska hur urbana typologier i Metro Boston presterar under en extrem värmehändelse. I avhandlingen ingår en litteraturöversikt som utforskar stadsvärmemetoder och stadsmorfologi, en undersökning av en uppsättning av städers klimatinsatsrapporter och en fjärravkänningsbaserad analys för att undersöka genomförbarheten att förena markytstemperaturen och offentliga väderstationsdata. Undersökningen av stadsklimatrapporterna visade att även om varje stad har börjat genomföra många socialt drivna initiativ och storskaliga gröna infrastrukturplaner, finns det i dagsläget lite arbete kring integrerande av stadsform i dessa strategier. Även om markytstemperaturen och väderstationskartan från fjärranalysanalysen ansågs otillräckliga uppstod flera värdefulla frågor och fynd genom processen.  Fallstudieanalysen av Metro Boston identifierade tre dominerande urbana former i studieområdet och 12 platser studerades i förhållande till deras värmeprestanda på morgonen, eftermiddagen och kvällen. De värmekartor som tillämpades utvecklades genom Heat Watch Report, ett samarbete mellan National Oceanic and Atmospheric Administration, kommunerna Boston, Brookline och Cambridge och CAPA Strategies. Analysen avslöjade en universell temperaturförändring bland alla former under dagen, med topptemperaturer som inträffar under sen eftermiddagsperiod. Studien visar också att medan temperaturskillnaderna mellan formerna inte var signifikanta, observerades variation mellan platser med samma form, med intern vegetationssammansättning och angränsande marktäkning och urban form som nyckelfaktorer för en ökad eller minskad upplevd värme.

Human interference with the Earth’s climate, through the release of greenhouse gasses (GHGs), is estimated to have already increased average statewide temperatures in California by 1.7° Fahrenheit (F), with a further 2.7°F of warming expected by mid-century. The negative impacts of increased temperatures may be especially acute in mid-latitude cities that currently enjoy a mild climate, such as Los Angeles (LA), which are projected to warm to a point that will significantly affect human health and well being. The built environment increases urban temperatures through building materials that readily absorb heat from the sun, a lack of vegetation, a lack of pervious surface area, and anthropogenic heat. Local governments can take action to help their cities adapt to future temperatures through changes to building materials, urban design and infrastructure. This study evaluates six urban design strategies for reducing temperatures and therefore adapting to increased heat in LA: cool roofs, cool pavements, solar panels, tree planting, structural shading and green roofs. The methods used in this analysis include a cost-effectiveness analysis, key stakeholder interviews, and case studies from other cities in the US. Findings indicate that cool roofs are the most cost-effective strategy for urban heat island mitigation, with cool pavements and tree planting also cost-effective. Findings from stakeholder interviews indicate that political feasibility is high for all strategies except structural shading, which was thought to be costly and difficult to implement. However, significant political barriers were also identified for tree planting and green roofs. Findings from four case studies indicate that climate adaptation policies should emphasize co-benefits, include flexible design standards, and provide financial or performance-based incentives for property owners or developers. Specific recommendations for implementing climate adaptation measures are provided for urban planners, policy makers, urban designers and architects in Los Angeles.

No description available.