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Analysis of Particle Pollution in an Office by the Concept of Perceived Particle Intensity

This paper is a study of the particle pollution in an office under two different ventilation modes, that is, mixing ventilation and displacement ventilation. The particle concentration distribution in a full scale office has been numerically simulated, while the size distribution of particles from copiers, which are regarded as a major particle source in offices, has been measured for numerical simulation. The results show that most particles generated by the copiers are in sub-micron range, with diameters of 0.5-2.0 m. Based on the numerical results of particle concentration distribution, the concept of perceived particle intensity (PPI) proposed in a previous study has been applied to evaluate the particle pollution in an office under two different ventilation modes. In addition the occupied density (OD) concept is employed to consider the occupant distribution. The results show that for the cases presented, side supply (mixing ventilation) is better than bottom supply (displacement ventilation) since in our construction the particle source (copier) was located close to the displacement diffuser, which implies that displacement ventilation needs to be carefully designed and adapted for actual application. It is hoped that it will be possible to evaluate particle pollution for different combinations of particle source locations and ventilation modes following the process presented in this study.