A methodology to investigate the particulate penetration coefficient through building shell

Dust penetration coefficient was defined to quantify the ability of building fabrics, door gap and window louver in reducing the amount of outdoor particulate matter brought into the building by infiltration. An office premises were selected as the controlled environment in this study. In order to minimize the impact of other factors, continuous measurements were conducted at night when the air conditioning units were turned off and when no indoor generation term was available. Exponential decay curves of the indoor particulate levels were obtained from which the penetrating coefficients were determined. Indoor dust removal mechanisms were discussed in the paper and within the experimental conditions, the dust penetration coefficients varied from 0.69 to 0.86. A cascade impactor was also used in the experiment to collect particle size distribution in the range of 0.43–10 μm. The size distribution was extended to the range of 0.05 μm by extrapolation technique. The modal size of the particulate matter (by mass conc.) was found at about 1 μm reflecting the inability of HVAC filter in removing dust around this size range. The dust penetration coefficient and size spectrum are useful for building researchers in quantifying influence of HVAC unit and building fabrics on indoor particulate characteristics.