A new process and its application for portable air cleaner sizing based on building particle load

Portable air cleaners play a crucial role in improving indoor air quality, which is especially important for vulnerable populations. Traditional methods of sizing portable air cleaners, based on a laboratory test, often fail to consider real-world conditions, including outdoor particle infiltration and indoor emissions. This study introduces a new concept of sizing process for portable air cleaners, considering both indoor and outdoor particle sources. It focuses on the building particle load calculation derived from the particle mass balance equation. The research evaluates the varying impacts of outdoor PM_2.5 concentration by geographical regions, building airtightness levels, and indoor source strengths while highlighting the specific needs of different outdoor design conditions with risk factors and indoor PM_2.5 concentration standards. The results indicate that in general, the air cleaner sizes calculated using both the traditional and newly proposed methods are sufficient to meet the indoor PM_2.5 concentration standard of 25 μg/m³ in a sufficiently airtight building (e.g., 1 ACH₅₀), regardless of outdoor PM_2.5 concentration levels. However, as airtightness decreases, traditional methods often yield insufficient air cleaner sizes. Moreover, in regions with very high outdoor PM_2.5 concentrations, air cleaner sizes required can be up to 15.4 times larger than those determined by traditional methods. The study findings indicate significant variability in appropriate portable air cleaner size, which can differ by an order of magnitude depending on the combination of geographical regions, building airtightness, and indoor source strengths.