Analysis of the influence of pressure difference across building envelope on indoor particulate matter concentration

Abstract

Outdoor PM_2.5, penetrated by infiltration, has a continuous and important effect on indoor environments. To determine the infiltration rate, it is important to consider the airtightness level and pressure difference across an envelope. This study investigated the influence of pressure difference and airtightness on indoor PM_2.5 in a residential building with natural ventilation. Field measurements were conducted in eight residential households. The indoor and outdoor PM_2.5 concentrations and pressure differences across the envelope were measured simultaneously. The airtightness of each unit was determined via a blower door test. As a result, the indoor PM_2.5 concentration exhibited a significant correlation with airtightness and envelope pressure difference. However, the correlation between the PM_2.5 I/O ratio and the pressure difference was found to weaken as the airtightness decreased. This appears to be influenced more by other external factors in addition to pressure under loose airtightness conditions. Thus, the influence of the factors on the penetration of PM_2.5 can vary depending on the airtightness of the envelope.