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The goal of this study is to bring out the efficiency of district landscaping on local urban heat island mitigation. Two cooling strategies at the district scale are evaluated through the coupled effect computation of microclimate and building energy demand: vegetation (trees, green walls and roofs) and high albedo values (cool roofs and façades). The study focus on an existing district, Part-Dieu, in Lyon (France). This district has a high urban density and is composed of buildings for which rehabilitation is expected to be difficult. The city is particularly sensitive to summer heatwaves that are supposed to be more regular with global warming. Two specific urban blocks, of about 10 building blocks each, are modeled: a 60,000 m 2 site where the urban fabric is a mix of historical buildings and 60s’ buildings, and a 70,000 m 2 new residential site under construction, more homogeneous compared to the first one. The simulation results are processed for a summer period (hourly time step) andcooling strategies are analyzed individually and combined. Two indexes, Energy Performance Index ( EPI ) and Ambient Temperature Mitigation Index ( ATMI ), are defined to evaluate strategy efficiencies. In our case studies, cooling energy demand is mitigated by around 3% with tree growth strategy, 35% with green roofs, and 76% with increased albedo of urban surfaces. Whereas detailed results of coupled simulation are useful here for engineers, global performance indicators defined in this study give useful hints for stakeholders and urban cooling strategy design. [ABSTRACT FROM AUTHOR]

A building influences its surrounding external environment, and its indoor environment is usually sensitive to its surroundings. In order to obtain a more accurate prediction of the indoor thermal behaviour of a building or a building stock, it is necessary to consider the interactions between the indoor and outdoor thermal environments. The modelling approach presented in this paper is based on a building energy model and the urban modelling tool SOLENE-Microclimat. A sensitivity analysis is undertaken to highlight the parameters which influence the performance of the building model. Then, the thermal indoor behaviour of a building is compared to in situ experimental measurements and the outdoor thermal environment is evaluated in terms of external surface temperatures. The model's accuracy and behaviour is evaluated and a crossover approach with the sensitivity analysis results is proposed. The model obtains a good level of performance for almost all variables, unless some external surface temperatures intervals. [ABSTRACT FROM AUTHOR]

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]