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The role of interzonal airflows is especially pronounced in naturally ventilated buildings. In such buildings, reversed airflows in the ventilation stacks might occur as well. This affects the air exchange rate and contaminant distribution in buildings. A significant increase in carbon dioxide concentration is a characteristic phenomenon for poorly ventilated rooms. This paper demonstrates the application of metabolic carbon dioxide concentration measurements for interzonal airflow estimation in naturally ventilated buildings. The presented method is based on the continuous measurements of CO2 concentration at one point in each zone. These measurements are used to estimate airflow pattern in a multizone building by applying an inverse analysis. The developed methodology employs an iterative Levenberg-Marquardt procedure to maximise the nonlinear likelihood function. The validity of the method was verified against measurements carried out in a single naturally ventilated room. Further, the method was applied to calculate the airflow pattern in two apartments in Poland, containing 4 and 6 zones. The obtained results revealed very poor ventilation in both investigated apartments and reversed airflow in exhaust ducts. The amount of fresh air entering the rooms was insufficient to ensure good indoor air quality. The developed methodology can be effectively used as a diagnostic tool to identify the potential problems with ventilation systems. [ABSTRACT FROM AUTHOR]

The computational fluid dynamics (CFD) analysis of the indoor environment in buildings requires numerical modelling of a human being (computer simulated person - CSP). There are two crucial aspectsin developing reliable CSP models: the CSP geometry and the breathing model. This paper focuses onthe analysis of different breathing models for application in the CFD modelling. Three breathing modelswere analysed: first model was restricted to constant exhalation, second model, the so-called full breath-ing, included constant rate inhalation, constant rate exhalation and pause period, and in the third modeltemporal variation of flow rate was represented by sinusoidal function. The main findings from this workshow that all three models compared with experimental data gave reliable results. The spatial distribu-tion of CO2 concentration and velocity showed only small differences among the models in the vicinityof the mouth and above the person. It was shown that a simplified constant exhalation model can beeffectively used for the CFD analysis of the indoor air quality (IAQ). However, a detailed simulation ofmicro-environment in the room and transport of contaminants should include complete breathing. [ABSTRACT FROM AUTHOR]