Novel computational tool for indoor air quality

This article introduces a novel computational tool for analysing concentrations of particles and gaseous impurities in mechanically ventilated indoor spaces. The computation routine exploits mass balance model assuming well-mixed conditions, and accounts for the most significant means of entry and loss of contaminants. The analysis inputs include time-dependent outdoor concentrations, indoor generation rates, filtration efficiencies and deposition rates. The model was validated using size resolved particle concentrations measured during an experimental campaign. The predicted indoor concentrations were in good correlation with experimental data over wide particle size range. To demonstrate the computational capabilities, indoor concentrations of particles and carbon dioxide were analysed with various combinations of supply air filtration efficiency, ventilation rate, recirculation ratio, air purifiers, and occupancy. Subsequently, a relative sick leave estimate based on time-averaged exposure to total particle mass concentrations was computed. The results emphasised the effectiveness of supply air filtration to limit the exposure to ambient air pollution. Replacing a coarse filter with a high efficiency filter resulted in reduction of an order of magnitude in the relative sick leave estimate. In comparison, increasing recirculation ratio or exploiting air purifiers demonstrated noticeable, but lesser impact.