Solar potential in extreme climate conditions: comparative analysis of two district case studies in Norway and Reunion Island

International audienceThis work aims to investigate the application and replicability of parametric solar design to both existing and future development urban areas in two extreme climate conditions: Øvre Rotvoll in Norway (subarctic climate) and Ravine Blanche in Reunion Island (tropical humid climate). The interplay between urban morphology and its potential for passive and active solar energy strategies has been investigated. The methodology combines the parametric modelling software Rhinoceros-Grasshopper, with two Radiance-based solar simulation tools to optimise the solar potential of a district. The application of a new workflow is studied over the computation of various design scenarios in an existing urban environment at both the district and the building scale. The results show differences and similarities between climate-specific interventions that can be used as supportive instruments for the ongoing local planning processes. The study demonstrates how parametric optimisation allows maximising the solar potential of urban areas at different latitudes despite climatic and urban densification constraints

Thermoregulatory effect of green spaces and wetlands in Paris

International audienceSeven "green and blue" areas of different kinds are selected in Paris in order to measure their "cooling effect" during summer heat-waves. Air temperature is measured at two meters height in three different locations of each site : one sensor is located in the middle of the green or blue area, one is located from 5 to 50 m away and the last one is located from 50 to 150 m away from the green or blue area. The intra and intersites temperature differences are qualitatively analysed all along the day regarding to the morphology and the land-use of the sensor environment. Results show that the smaller is the park, the lower will be its cooling effect. The canal does not refresh well the air during night-time whereas its does refresh during day-time. Large areas mainly composed of low vegetation and a judicious distribution of trees seem to have the best potential to decrease the air temperature inside and outside the green area during day-time as well as during night-time. Quantitative analysis as well as denser measurement network should be implemented in order to confirm those preliminary conclusions

How to evaluate nature-based solutions performance for microclimate, water and soil management issues – Available tools and methods from Nature4Cities European project results

International audienceIn 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

Génération automatique de modèles zonaux pour l'étude du comportement thermo-aéraulique des bâtiments

This study consists in showing that it is possible to automatically build zonal models that allow to predict air movement, temperature distribution and air quality in the whole building. Zonal models are based on a rough partitioning of the rooms. It is an intermediate approach between one-node models and CFD models. One node models consider an homogeneous temperature in each room, and for that reason, do not permit to predict the thermal comfort in a room whereas CFD models require a great amount of simulation time. To achieve this aim, the zonal model was entirely reformulated as the connection of small sets of equations. The equations describe, either the state of a sub-zone of the partitioning (such sets of equations are called « cells »), or mass and energy transfers that occur between two sub-zones (then, they are called « interfaces »). There are various « cells » and « interfaces » to represent different air flows that occur in buildings. They all have been translated into SPARK objects that form a model library. Building a simulation consists in choosing the appropriate models to represent the rooms, and connecting them. The last stage has been automated. So, the only thing the user has to do is to give the partitioning and to choose the models to be implemented. The resulting set of equations is solved iteratively with SPARK. Results of simulations in 3D-rooms are presented and compared with experimental data. Examples of zonal models are also given. They are applied to the study of a group of two rooms, a building, and a room the geometry of which is complex.Cette étude a pour objet de montrer qu'il est possible de générer automatiquement des modèles zonaux pour l'étude du comportement thermique et aéraulique des bâtiments. Les modèles zonaux sont basés sur le partitionnement des pièces en un petit nombre de sous-volumes. Cette approche est intermédiaire entre celle des modèles à un noeud (qui considèrent que la température est homogène dans chaque pièce, et pour cette raison ne permettent pas de prédire le confort thermique dans une pièce) et celle des codes CFD (qui sont très coûteux en temps de calcul). Pour atteindre notre objectif, nous avons reformulé le modèle zonal. Ceci a consisté à regrouper les équations de description du comportement du bâtiment dans des sous-systèmes d'équations. Ce regroupement est calqué sur le découpage spatial des pièces. Ainsi, les équations de bilan et d'état appliquées à un sous-volumes forment les modules de la famille des « cellules » et celles de transfert entre deux sous-volumes forment les modules de la famille des « interfaces ». Ces familles sont constituées de plusieurs modèles correspondant aux différents types d'écoulement qui se développent dans les bâtiments. Ceux-ci ont été traduits en objets SPARK, lesquels forment la bibliothèque de modèles. Construire une simulation consiste à choisir les modèles appropriés pour décrire les pièces et à les connecter. Cette dernière étape a été automatisée, si bien qu'il ne reste plus à l'utilisateur qu'à donner le partitionnement et à choisir les modèles qu'il désire implémenter. Le système d'équations résultant est résolu par le solveur de SPARK. Des résultats de simulations pour différentes configurations d'écoulement dans des pièces sont présentés et comparés à des données expérimentales. Nous donnons également des exemples d'application de la méthode zonale à l'étude d'un groupe de deux pièces, d'un bâtiment et d'une pièce de géométrie complexe

L’étude des microclimats urbains : champ de recherche à l’interface entre climatologie, urbanisme et génie-civil

In this paper, we set the research field for the study of urban microclimates in relation to current issues of sustainable urban development and in relation to neighbouring research fields. Indeed, for solutions in response to climate change, this research field needs to address its research objects (urban form, land use, green frame, human activities...) differently. Moreover, in a context of sustainable development, these objects are now considered as the intersection of multiple environmental, social and economic challenges. We explore the interaction between disciplines by focusing specifically on the case of the object of research that are the green frames. At first, we explain why the green frames are of interest for the urban microclimate sciences. It’s an opportunity to make an update on current knowledge of the climatic role of green frames and to sketch the climate research perspectives involved. These perspectives highlight the necessity is for researchers to have knowledge, methods and techniques from other disciplines. We explain some of the articulations with geomatics, plant biology, hydrology, etc. caused by this object of study. We also show how the knowledge produced by the urban micro-climatology can be useful in other areas

L’étude des microclimats urbains : champ de recherche à l’interface entre climatologie, urbanisme et génie-civil

Dans cette contribution, nous positionnons le champ de recherche qui concerne l’étude des microclimats urbains par rapport aux problématiques actuelles du développement urbain durable et par rapport aux champs de recherche voisins. En effet, pour proposer des solutions en réponse au changement climatique, ce champ de recherche doit aborder ses objets de recherche (forme urbaine, occupation des sols, trame verte, activités humaines, etc.) différemment. Par ailleurs, dans un contexte de développement durable, ces objets sont maintenant étudiés comme étant au croisement de multiples enjeux environnementaux, sociaux et économiques. Nous explorons ces échanges entre disciplines en nous intéressant plus particulièrement au cas de l’objet de recherche que constituent les trames vertes. Dans un premier temps, nous expliquons en quoi les trames vertes intéressent les sciences du microclimat urbain. Nous faisons à cette occasion un point sur les connaissances actuelles du rôle climatique des trames vertes et les perspectives de recherche. Ces perspectives mettent en évidence la nécessité qui s’impose aux chercheurs de disposer de connaissances, méthodes et techniques venant d’autres champs disciplinaires. Nous explicitons certains des points d’articulation avec la géomatique, la biologie végétale, l’hydrologie, etc., occasionnés par cet objet d’étude. Nous montrons également en quoi les connaissances issues de la micro-climatologie urbaine peuvent être utiles dans d’autres domaines.In this paper, we set the research field for the study of urban microclimates in relation to current issues of sustainable urban development and in relation to neighbouring research fields. Indeed, for solutions in response to climate change, this research field needs to address its research objects (urban form, land use, green frame, human activities...) differently. Moreover, in a context of sustainable development, these objects are now considered as the intersection of multiple environmental, social and economic challenges. We explore the interaction between disciplines by focusing specifically on the case of the object of research that are the green frames. At first, we explain why the green frames are of interest for the urban microclimate sciences. It’s an opportunity to make an update on current knowledge of the climatic role of green frames and to sketch the climate research perspectives involved. These perspectives highlight the necessity is for researchers to have knowledge, methods and techniques from other disciplines. We explain some of the articulations with geomatics, plant biology, hydrology, etc. caused by this object of study. We also show how the knowledge produced by the urban micro-climatology can be useful in other areas

L’étude des microclimats urbains : champ de recherche à l’interface entre climatologie, urbanisme et génie-civil

In this paper, we set the research field for the study of urban microclimates in relation to current issues of sustainable urban development and in relation to neighbouring research fields. Indeed, for solutions in response to climate change, this research field needs to address its research objects (urban form, land use, green frame, human activities...) differently. Moreover, in a context of sustainable development, these objects are now considered as the intersection of multiple environmental, social and economic challenges. We explore the interaction between disciplines by focusing specifically on the case of the object of research that are the green frames. At first, we explain why the green frames are of interest for the urban microclimate sciences. It’s an opportunity to make an update on current knowledge of the climatic role of green frames and to sketch the climate research perspectives involved. These perspectives highlight the necessity is for researchers to have knowledge, methods and techniques from other disciplines. We explain some of the articulations with geomatics, plant biology, hydrology, etc. caused by this object of study. We also show how the knowledge produced by the urban micro-climatology can be useful in other areas

Seven questions around interdisciplinarity in energy research

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