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A lot of geographers, scientists believe that the current climate has changed. Especially, since the rapid increment of world's population. Indeed, rapid urbanization led to an increased demand of basic facilities, such as public transport services, hospitals, housing &, etc. Accordingly; the urban areas of cities have been expanded compared to rural areas, and many modifications and changes have been happened on their surface's materials. These modifications made our cities hotter than the Countryside, UHI effect phenomenon now well-known. One of the main reasons behind these changes is construction materials in both buildings and urban spaces, which play a major role in affecting the urban temperatures, precisely near-surface air temperatures positively or negatively, which depend mainly on the behaviour of the surface with solar radiation and how the energy is reflected, emitted, and absorbed. Thus, the current study aimed to investigate the direct and indirect impacts of materials reflection coefficient on the environmental performance and external urban surface temperature; by using the SOLENE-microclimate model tool (developed by the laboratory CRENAU - ENSA Nantes); which is a direct effect on external air temperature in terms of sustainability in the urban context. This study applied on one of the most important residential complexes in Mosul city - Iraq as a case study. The results were proved that when used a material with high reflectivity; Comparing low albedo Scenario(1) with high albedo Scenario(3); it can improve the thermal behaviour of building and urban surfaces, where the surfaces temperature of rooftop, walls, urban spaces, road have been changed by, respectively, 25°C, 18°C, 20°C, and 18°C. As well as changed the urban air temperature by 11°C. However, the results showed that in some cases the surface temperatures increased slightly even when reflectivity increased in the scene, (comparison scenario 3 and scenario 5) where the change of albedo value of external walls surfaces have affected increasing the average urban spaces & pavement temperature about 2°C. The tool that is used in this study (SOLENE-microclimate) has effectively helped in achieving all the analysis required successfully, which it represent the most specialized tool in this field. [ABSTRACT FROM AUTHOR]

The urban population rise leads town planners to increase the building density in order to avoid an urban sprawl what can induce higher risks of the heat island occurrence and increases buildings needs for air conditioning. Urban vegetation such as trees, grass areas, green walls and roofs can be a solution to mitigate it. The aim of the study is to evaluate the influence of various greenery types on cooling needs and to classify them according to their ability to mitigate it. Numerical simulations were carried out for canyon street configurations. The 3D numerical tool takes into account the unsteady building thermal behaviour using the SOLENE thermo-radiative model coupled with the outside airflow computed with the CFD tool Code_Saturne. A parametric modelling study considering different kinds of buildings permits to identify the most efficient greenery types and to investigate the interactions between each of them. Green walls and trees appear as the most efficient to reduce cooling needs. The less insulated and the more glassed the buildings are, the more efficient these devices are. The impact of grass areas and green walls applied on neighbouring buildings is only sensible without trees in the street and green cover on the studied building. [ABSTRACT FROM AUTHOR]

The urban microclimate is due to complex physical interactions with the contribution of water balance, thermo-radiative exchanges and airflows. In this paper, we present and discuss modeling of heat island effects and mitigation techniques in order to give consistent results considering different time and space scales, and different fluxes (heat, water and winds) from ground to urban canopy, including buildings. The models and numerical descriptions are presented in detail and illustrated on typical examples of heat island mitigation techniques. At the neighborhood scale, alternative rainwater management techniques are studied by considering their impact on both seasonal water table depth and surface-atmosphere heat fluxes. Assessing the building thermal performance interactions with the microclimate requires adapted models that have to be refined for a better description of building envelope and systems effects. Two examples at the street and the neighborhood scale, modifying the building radiative properties or using green envelopes, show how simulation brings out the potential benefits of these techniques for the heat island mitigation and building energy performance. [ABSTRACT FROM PUBLISHER]

Since some years, dense cities and compact buildings are promoted as sustainable and energy efficient designs. Nevertheless, urban planning strategies should take into account the interactions between buildings and the microclimate because the Urban Heat Island (UHI) phenomenon can increase the cooling load of buildings and is strongly influenced by urban morphology, urban landscaping and the thermal properties of buildings and soil. The modification of these parameters, such as building density, can mitigate UHI, with direct and indirect improvement of building energy performances. The case study presented in this paper concerns a new district in La Rochelle (France) named Atlantech. Currently at the design stage, the goal is to transform this old military camp into a zero carbon district. This study was performed in parallel with urban planning using EnviBatE and SOLENE-Microclimate simulation. Two building densities are compared through the impacts on solar irradiance, wind airflows, building indoor temperatures and energy demand. Analysis of reference and densified district highlights various impacts such as the wind velocity decrease, up to 80%, and the effect on an existing nearby building solar irradiation, reduced by 7%. These results underline the potential usefulness of these simulation tools for urban planners at the design stage. [ABSTRACT FROM AUTHOR]

• An evaluation toolbox to consider nature-based solutions in urban areas is settled. • Impact of nature-based solutions depends on urban environmental challenges. • A decision-support methodology considering soil-water-climate aspects is developed. • Several indicators were determined and compared to define the toolbox. In the context of climate change, Nature-Based Solutions (NBSs), a recently developed concept, are increasingly considered as part of the adaptation strategies of the cities. Studies using expert models and methods (EMM) receive a great deal of scientific attention. Considering EMM increasing use, this study aims to perform an analysis of the reported evaluation results, reflecting the capability of the EMM to accurately tackle urban challenges identified within the EU Nature4Cities project. Then, we propose a set of indicators and recommendations about sixteen EMM to be used by funders, researchers and practitioners when evaluating the performance of NBSs. The coupling of the different components (climate, water and soil) is not a simple matter. The analysis relies on the definition of the range of the reported metrics and on the investigation of the relationship between the various indices, applied for the EMM evaluation. Secondly, the study assesses the existing EMM, indicating the potential of NBSs: (i) to reduce urban heat island, (ii) to limit surface warming, (iii) to increase the thermal comfort of people, (iv) to limit the overheating and runoff of surfaces due to impervious areas, (v) to increase water retention during stormy episodes, (vi) to improve storm water quality at the outlet of the sustainable urban drainage systems, (vii) to promote the filtration and epuration of storm water runoff in soil and (viii) to be a support for vegetation. The analysis reveals that EMM can be considered as helpful tools for urban microclimate, urban soil and water management analysis, provided their limitations and characteristics are taken into account by the user when choosing tools and interpreting results (e.g. application scale). With regard to the performance of NBSs, the most commonly used indicators clearly depend on the scale of the project. [ABSTRACT FROM AUTHOR]