Thibaut Vairet is denfending his PhD thesis : Sensitivity of a climate model to urban form. Application on Dijon Métropole

 

The defense will take place in Dijon at the University of Burgundy on december 14th

 photo Vairet Thibaut 1

This work was directed by Thomas Thevenin, Associate researcher "HDR" ThéMA and Yves Richard, Associate researcher "HDR", Biogéoscience-CRC.

The defense can be followed online by : http://desktop.visio.renater.fr/scopia?ID=727610***8300&autojoin

Code d'accès : 8300 (terminer par #)

 

Defense jury

Houet Thomas, Director of Research "HDR" CNRS, LETG, Rennes

Masson Valéry,  Director of Research HDR, GMME/VILLE, CNRM, Toulouse

Cantat Olivier, Associate researcher, LETG, Caen

Ruas Anne, research ingenior "HDR", IFFSTAR, Marne-la-Vallée

Sanders Léna, Director of research "HDR" CNRS,Géographie-Cité, Paris 1

 

Abstract

The urban environment is at the crossroads of two complex systems with different temporalities : climate and society. The urban climate is a modification of the climate caused by the presence of a city. The most successful expression of this climate change by the presence of the city is the phenomenon of Urban Heat Island (UHI). In a global context of adaptation and mitigation to climate change and urban development, this phenomenon of ICU tends to increase, and its health impacts on populations to become more prominent. This work is aimed at improving the knowledge of the impact of urban form and urban development on the intensity of the UCI through the implementation of a decision support tool allowing to integrate urban climate into decision-making processes. To do this, a “ model-dependent ” approach has been adopted. Five urban growth scenarios are based on the same number of housing but correspond to different Local Climate Zones (Grouped individual housing - LCZ 9, Individual group housing - LCZ 6, Low density collective - LCZ 3, Collective - LCZ 2, Dense collective - LCZ 4). These are developed by 2050, based on input data from growth models (MUP-City) and urban climate (Meso-NH / TEB). In order to assess the ability of Meso-NH / TEB to reproduce temperatures in Dijon Métropole, a control simulation, relating to the current city, is previously compared with data from the MUSTARDijon network for the heat wave period from 22 to 26 July 2018. A comparison of the results with the MUSTARDijon textit in situ network shows that the simulated temperatures are spatially and temporally consistent with the observations. The diurnal cycle is correctly modeled as well as urban and rural environments. A significant bias is present at nights in rural areas where temperatures remain high, limiting the intensity of the simulated UI. Compared to the control simulation, for the days (12LT to 18LT), the scenario with LCZs 3 and 2 present warmer temperatures than the scenario with LCZs 9 and 6. The scenarios for which the building percentage is the smallest has the smallest temperature increases. Finally, it would seem that building, whatever the urban form, on the outskirts of already defined built-up areas, has little impact on their temperature.

 

François Sémécurbe is denfending his PhD thesis : Analysis of the spatial distribution of human settlements : Contributions and limitations of multi-scale and trans-scale indicators

 

The defense will take place in Besançon at the University of Franche-Comté at Salon Préclin, UFR SLHS on september 25th at 2 pm.

 

This work was directed by Cécile Tannier, Senior researcher at CNRS (French National Centre for Scientific Research).

 

Defense jury

Elsa Arcaute - Associate professor, CASA, University College London
Giovanni Fusco - Associate researcher "HDR" at CNRS, laboratory ESPACE, Nice
Didier Josselin - Director of Research CNRS, laboratory ESPACE, Avignon
Julien Perret - Director of Research LASTIG, Paris
Pierre Frankhauser - Emeritus Professor at the University of Franche-Comté, laboratory ThéMA
Stéphane Roux - Lecturer – HDR, ENS de Lyon, laboratory of physics

 

Abstract

As human beings, it is easy for us to judge visually whether a distribution is dispersed or concentrated. However, the quantitative formalization of our impressions is problematic. It depends on the scales of the chosen analysis. This dependence of indicators on scales has changed. It is initially considered as a barrier to knowledge, it now reflects the multi-scale organisation of the distributions studied. The central objective of this thesis is to investigate the limits and contribution of multi-scale and trans-scale indicators to the study of the spatial distributions of human settlements. Spatial analysis aims at comparing spatial distributions to a uniform distribution. The way in which spatial distributions move away from this reference is used to characterize the multi-scale organization of the analyzed distributions. The application of these methods to human settlements has not been satisfactory. The use of an exogenous reference is not adapted to distributions that are very unevenly concentrated in space. Fractal analysis used in urban geography considers that the analysed distributions are their own measurement standard. Fractal dimensions measure how the space occupied by them evolves across scales. This type of analysis requires a regularity between scales, the invariance of scale whose existence is not verified on all territories. Trans-scale analysis generalises the principles of fractal analysis to all distributions and makes it possible to characterise the unequal concentration of human settlements in rural and urban territories.

 
 

 

Jean Houssemand is defending his PhD thesis : Conceptualization and evaluation of a typology of vertical housing concept for sustainable urban planning

 

The defense will take place in Dijon at the University of Burgundia at the Maison des Sciences de l'Homme, Salle des Thèses (6 Esplanade Erasme), on february 14th at 14pm.

 

This work was directed by Jean-Philippe Antoni, Professor at the University of Burgundy, laboratory ThéMA.

 

Defense jury

Denis Bocquet, Professor at the National School of Architecture of Strasbourg

Éric Charmes, Director of Research at the Laboratory for interdisciplinary research on cities, spaces and society (EVS RIVES), Graduate School of Civil, Environmental and Urban Engineering, Vaulx-en-Velin

Pierre Frankhauser, Emeritus Professor at the University of Franche-Comté

Hélène Haniotou, Professor at the National Technical University of Athens, Greece

 

Abstract

Context. The current urban development process is the result of a paradoxical situation. On the one end, families prefer individual housing, which finds the favourable conditions to its spreading in the more or less distant from towns outskirts, while wishing to benefit from services (proximity to amenities, public transport offers, etc.) which are rather the corelate of dense urban centralization. On the other hand, in order to fight against environmental, social and economic costs of urban sprawl, and also aim towards a more sustainable city, the urban renovation and compact city projects lead to some density levels that only collective housing enables to reach.

Problematic. So, the equation « control of the urban sprawl, satisfaction of the house request and sustainable city » seems to be unsolvable, especially due to the lack of a housing offer being able to combine the particularities of the detached house and the needs of urban density. Two relatively separate tandems « housing / territory and induced mobility » result from it : individual housing, which is dependent on cars, is mainly situated in peri-urban areas, whereas collective housing, which is not approved by most families, gather in the town centers with many alternatives to cars. In such a context, through the main concept of « vertical housing development », this doctoral research work arises the hypothesis that the enlargement of the prism of the mobilities and urban areas analysis should enable the emergency of new solutions, which will include the housing and territories specifications in a multidisciplinary and multiscale way.

Methodology. In order to confirm this hypothesis, the methodology hinges on two steps. First, a review of the architectural literature allowed to define the « vertical housing concept » as an innovative answer to the equation which is insolvable nowadays : indeed, the history of architecture informs us profusely on the opportunities of a vertical urbanism unexploited until now ; this enables the creation of hanging artificial grounds to build in floors detached houses. In second place, the state of the art allowed to identify the main determinants of housing attractiveness while confronting the two classical tandems (individual/collective) to the concept of « vertical housing development » and suggests a theoretical model adaptable to different cases. Validation. The model has been evaluated three times. Firstly, the information gathered during a photo-elicitation inquiry allow to validate the architectural choices a posteriori and make sure of their suitability in terms of residential preferences (social validation). Secondly, a legal evaluation shows that a development of the current regulatory measures is indeed partially necessary to the operational development of the model, but the latter can nevertheless quickly fulfill the demand while fighting against urban sprawl. Thirdly, a geographical evaluation which compares the deployment of the model with the reality of available grounds and the localization of amenities and transport infrastructure, shows that it would concretely allow to densify the town and its outskirts according to a logic close to the Transit Oriented Development (TOD). Results. Three major results arise from this evaluation. Indeed, the « vertical housing development » concept seems (i) to match with the residential choices from a significant part of the French families, (ii) to be immediately authorized and managed by the current legal and regulatory framework, (iii) to benefit from a consequent potential of development at the level of the Strasbourg-Eurometropolis which serves as an example to this thesis. Moreover, at a time when multidisciplinary and multiscale approaches are questioned, this thesis work, which links an architectural approach at the housing level and a geographical approach at the city level, gives a specific example of new types of housing formalization, based on the original principle of a decoupling between « housing types » and « territories ».

 

Keywords : Housing types, Housing concept, Urban form, Urban renewal, Compact city, Sustainable city, Evaluation, Modelization, Multidisciplinarity, Multiscalarity

Housemand ill thèse 


 

 

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