CSTB - Gestion de la qualité sanitaire des espaces clos : amélioration des outils de gestion de l'impact des polluants gazeux des sols en relation avec la qualité de l'air intérieur des bâtiments

Abstract : Transfer of soil gas pollutants (Radon, VOC) into buildings can cause significant health risks. However, analytical models used today to estimate health risks associated with these pollutants contain many uncertainties which can lead to poor risk assessment. Initially, the main objective of this research is to contribute to the improvement of these models for risk assessment. Secondly, the development of air flow model for passive Sub slab Depressurization Systems (SDS) design used to protect buildings is proposed. The improvement of models focused on the inclusion of the main phenomena of convection and diffusion at building/soil interface, taking into account different types of building substructures. The first improvement concerns the assessment of convection phenomenon through the development of analytical models to quantify air flow rates entering through many kinds of building substructures: floating slab, bearing slab, crawl space and basement. Buildings with buried walls and substructures with a sub slab gravel layer are also treated. A methodology taking into account the presence of cracks, holes and singular leakages of the slab is also proposed. The second improvement of the models is the inclusion of coupled transfer of convection and diffusion near foundations. A numerical study allowed a better understanding of the behavior of pollutants at soil / building interface. Based on this understanding, semi-empirical laws for estimating soil gas pollutants entry rate into buildings are proposed. The various models developed have been validated numerically using a CFD model and experimentally with data from the literature when available. The impact of building substructure on pollutant transfer has been highlighted. A first application of the models is illustrated by their integration into a multizone simulation code to study the impact of these transfers on indoor air quality. Finally, the work ends with the development of a model for designing passive sub slab depressurization systems. The design model developed is validated with in situ experimental data. Preliminary applications using this model focused at first on the impact of meteorological conditions (stack effect, wind) on the sub slab system running. At second, the impact of ventilation strategies on sub slab depressurization performance is studied. Thus, the potential interest of this model to test the effective running of passive sub slab depressurization systems in given configuration is shown.
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B. Collignan, E. Powaga, T. Diallo. CSTB - Gestion de la qualité sanitaire des espaces clos : amélioration des outils de gestion de l'impact des polluants gazeux des sols en relation avec la qualité de l'air intérieur des bâtiments. 2013. ⟨hal-01057501⟩

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