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Abstract: Predicting the indoor air relative humidity evolution is of great importance to evaluate people thermal comfort, perceived air quality and energy consumption. In building environments, porous materials of the envelope and furniture act on the indoor air humidity by reducing its variations. Solving the physical processes involved inside the porous materials requires the knowledge of the material hygrothermal properties that needs multiple and, for some of them, time-consuming experimental procedures. Recently, both the NORDTEST Project and Japanese Industrial Standard described a new Moisture Buffer Capacity index that accounts for surrounding air vapor concentration variation. The Moisture Buffer Value (MBV) indicates the amount of water vapor that is transported in or out of a material, during a certain period of time, when the vapor concentration of the surrounding air varies. The MBV evaluation requires only one experimental procedure and its value permits a direct comparison of the building materials moisture performance. However, two limitations can be distinguished: first, no relation between the MBV and the usual material hygrothermal properties has been clearly identified and second, no model has been proposed to actually use the MBV in building simulation. The present study aims to solve these two problems. First, the MBV fundamentals are introduced and discussed; followed by its relation with the usual material properties. Then, a lumped model for building simulation, whose parameters can be determined from the MBV experimental procedure, is described. To finish, examples of the use of this MBV-based lumped model for moisture prediction in buildings are presented. [Copyright &y& Elsevier]

Abstract: With the increase of the computational capability, three-dimensional Lagrangian simulation can now be applied to evaluate the particle pollution evolution in ventilated rooms. The present study deals with the evaluation of 5.0μm particle dispersion in a prototypical-ventilated room of 10m3. Two ventilation slots and three different airflow rates have been simulated. Particle trajectories have been calculated using a Lagrangian model. Dispersion of particles has been analyzed for the case of an external pollutant source, a homogeneous particle injection within the room and some puff releases in different locations. Discussion about the best procedure to get useful information about the particle cloud is then presented and illustrated from the simulation results. The definition of two indices based on geometrical and statistical parameters are proposed in order to correctly evaluate the particle cloud homogeneity and mixing time. [Copyright &y& Elsevier]

Abstract: In recent years, several intensive studies have been carried out in order to reduce the energy consumption of buildings. One solution lies on whole building energy simulation that permits to enable the heat (and moisture) transfer through the building envelope and, consequently, is a way to understand how to improve the building performance. This article aims to analyze the modeling level needed to successfully evaluate the heat transfer through glazing parts of windows in such whole-building simulations as it is well-known that windows are the thermally weakest elements of the building envelope. In this way, predictions of glazing surface and zone air temperatures and energy demand obtained using both resistive and finite-volume based models are compared. Results show that for common window glazing structure and outdoor/indoor perturbations, differences between the two models are small. However, in the case of glazing presenting higher solar absorption and thermal inertia, the use of the finite-volume based model is required to accurately predict the glazing internal surface temperature and avoid errors up to 50% for energy consumption in the studied case. Those results put into relief a clear limitation of current whole energy simulation programs to correctly predict the energy consumption of buildings where high thermal inertia double- or triple-glazing windows are installed. [Copyright &y& Elsevier]