To better predict the effective energy performance of buildings in cities, this study addresses the modelling of local external radiative, thermal and aeraulic conditions. After reviewing existing modelling approaches that are suitable for estimating the building boundary conditions in energy simulation, this paper analyses external conditions derived from a building energy model (BuildSysPro) or a microclimatic model (SOLENE microclimat). Comparisons are made for the different faces of a generic building standing alone or located in an urban environment, with or without a thermally efficient envelope. When the modelling approach is adjusted, the results highlight significant deviations on the estimated radiative temperatures and wind-based quantities around the isolated building. When accounting for surrounding buildings, the results show a substantial reduction in short-wave radiative fluxes, which is explained by an imbalance between solar masks and multireflections, and a reduction in the wind-driven ventilation potential.

Most of the building energy models are not suited to properly integrate local urban ambient conditions; thus, this study initiates a sensitivity analysis of the heating and cooling needs and operative temperature of buildings to local radiative, thermal and aeraulic external conditions. These conditions were estimated using the possibilities of a building energy model (based on the BuildSysPro Modelica library) or derived from microclimatic simulations (SOLENE microclimat) for generic isolated or urban buildings. The thermal behaviors of both energy-inefficient and energy-efficient buildings in summer and winter are examined. The results show major effects of short- and long-wave radiative heat transfers as well as aeraulics. According to present results, and given current urban growth and climate change challenges as well as the development of energy conservative buildings, this last point may become particularly critical in the future.