Whole House Particle Removal and Clean Air Delivery Rates for In-Duct and Portable Ventilation Systems

Abstract

A novel method for determining whole house particle removal and clean air delivery rates attributable to central and portable ventilation/air cleaning systems is described. The method is used to characterize total and air-cleaner-specific particle removal rates during operation of four in-duct air cleaners and two portable air-cleaning devices in a fully instrumented test home. Operation of in-duct and portable air cleaners typically increased particle removal rates over the baseline rates determined in the absence of operating a central fan or an indoor air cleaner. Removal rates of 0.3- to 0.5-μm particles ranged from 1.5 hr⁻¹ during operation of an in-duct, 5-in. pleated media filter to 7.2 hr⁻¹ for an in-duct electrostatic air cleaner in comparison to a baseline rate of 0 hr⁻¹ when the air handler was operating without a filter. Removal rates for total particulate matter less than 2.5 μm in aerodynamic diameter (PM_2.5) mass concentrations were 0.5 hr⁻¹ under baseline conditions, 0.5 hr⁻¹ during operation of three portable ionic air cleaners, 1 hr⁻¹ for an in-duct 1-in. media filter, 2.4 hr⁻¹ for a single high-efficiency particle arrestance (HEPA) portable air cleaner, 4.6 hr⁻¹ for an in-duct 5-in. media filter, 4.7 hr⁻¹ during operation of five portable HEPA filters, 6.1 hr⁻¹ for a conventional in-duct electronic air cleaner, and 7.5 hr⁻¹ for a high efficiency in-duct electrostatic air cleaner. Corresponding whole house clean air delivery rates for PM_2.5 attributable to the air cleaner independent of losses within the central ventilation system ranged from 2 m³/min for the conventional media filter to 32 m³/min for the high efficiency in-duct electrostatic device. Except for the portable ionic air cleaner, the devices considered here increased particle removal indoors over baseline deposition rates.