Using low-cost particle sensors in HVAC ducts

Low-cost sensors (LCSs) are increasingly used to measure particulate matter (PM). The possibility of using this kind of sensor within the HVAC system opens opportunities for improved control and management of indoor air quality and predictive maintenance of air filtration systems. This experimental study evaluates the effectiveness of LCSs in detecting particles within air ducts, employing three distinct types of LCSs under different testing aerosols, particle concentrations, and airstream velocities with particular emphasis non-statutory concentrations of PM2.5 and PM10. Data analysis includes statistical assessments to determine correlations and agreements to a reference laboratory-grade optical spectrometer (TSI OPS 3330). The findings underscore the suitability of LCSs for relative measurements, especially for PM2.5 concentrations, with varying degrees of accuracy for PM10 concentrations. In particular, one LCS did not perform well for PM10 for either a standardized test aerosol or for measurements of outdoor aerosol, potentially owing to the lack of a sampling fan in the sensor. The other two sensors generally had a linear response with the reference instrument for PM2.5 under test conditions with both the standardized aerosol and outdoor aerosol and at different velocity conditions. However, the agreement was generally worse at higher velocity conditions, especially for PM10, suggesting challenges associated with accurate PM10 assessments with the tested LCSs. This investigation highlights opportunities and constraints for using LCSs in HVAC systems.