<p><strong>Abstract.</strong> The aim of this paper is the modelling of urban microclimate, based on the limits imposed by the complexity of the three-dimensional space of cities. To this purpose, different Bioclimatic Scenarios were investigated through the microclimatic simulations using the micro-scale numerical model, ENVI-met 4v, applied in a case study of a Block in a highly residential neighbourhood of Athens. The study compares the bioclimatic scenarios of the roof top and road side vegetation plan in the current conditions, in order to evaluate how the existence of vegetation can affect the local air temperature and the thermal comfort condition of urban environment. This study also highlights the need to manage those microclimate data, through a geodatabase and provides a GIS approach of data organization and visualization. Creating building facades of the distributed temperature has showed that urban morphology parameters have an obvious impact on temperature distribution in the 3D space. On the other hand, the proposed roadside vegetation scenario has proved to be the most suitable way to improve the thermal comfort conditions of urban environment, as it can eliminate the Urban Heat Island (UHI) effects.</p>

Abstract. Smart Cities are complex distributed systems which may involve services, applications, sensors and IoT devices. In order to be able to link and use such heterogeneous data, spatial data infrastructures for Smart Cities can play an important role in establishing interoperability between systems and platforms. Semantic 3D city models describe spatial, graphical and thematic aspects of the city objects according to the CityGML international standard, issued by the Open Geospatial Consortium (OGC). The requirement to support energy time-dynamic properties within CityGML objects arises from the fact that cities yield great potential in terms of energy consumption reduction and efficiency increase. In order to support such time-varying energy properties concerning city objects, recent extensions of the CityGML in the form of Application Domain Extensions (ADEs) are researched and developed, such as the Energy ADE and the Dynamizer ADE. Starting from a Building Information Model (BIM) and evaluating energy use of the building through the created Building Energy Model (BEM), the aim of this study is to integrate and visualize the time-based energy simulation results with the 3D building model within a 3D semantic city model. Using the latter ADE, the highly detailed static 3D Building (LOD 4) is extended to support those energy variations of individual feature properties and associations over time. Moreover, the web-based visualization approaches and data retrieval were further researched, and an interoperable web-based application was developed, in order to accomplish an integrated knowledge on how time-series data can be distributed in a virtual 3D environment.

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