A New PM2.5-based PM-up Method to Measure Non-Mechanical Ventilation Rate in Buildings

Air exchange rate (AER) is related with sustainable development of human society. Its convenient measurement in realistic environments remains a challenge due to disturbance for occupants' normal activities. This study developed a new PM-up method to overcome this challenge. This method uses PM2.5 as tracer and determines non-mechanicntal ventilation rate by fitting a model to indoor PM2.5 concentration in an initial bouncing period. Compared to results by mostly used CO2 decay methods, PM-up method has a normalized mean error (NME) of 0.27 and correlation coefficient (r) of 0.69 for AER smaller than 1 h(-1) (n = 39). For all the tests (n = 73), NME is 0.35 and r is 0.76. This indicates satisfactory performance of the PM-up method for engineering application. The method's performance seems not impacted by fitting coefficient, AER level, or indoor PM2.5 concentration. We applied the method to continuously measure hourly nonmechanical AER in 6 days, indicating its feasibility in practice. This PM-up method offers new option to measure non-mechanical AER with little disturbance to occupants' normal activities.