Are low-cost sensors good enough for IAQ controls?
This study used laboratory testing to evaluate low-cost (about $200 US) IAQ monitors that measured PM2.5 to determine if they are suitable for controlling IAQ for ventilation or air cleaning systems.
Current Indoor Air Quality (IAQ) standards and approaches to minimizing pollutants depend almost exclusively on using dilution with outdoor air for some generic, continuously generated contaminant (e.g., ASHRAE Standard 62.2-2016). Some standards include measurement of CO2 (e.g., EN 13779 standard (CEN, 2007) and NEN 8088 (NEN, 2011)) – however this is not because CO2 itself is a pollutant of concern, but rather because it can be used as an occupancy indicator or as something that correlates with bioeffluents. Ideally, we would like to measure contaminant concentrations directly and ventilate to control their concentration within acceptable limits. This would ensure that concentrations do not got too high (as they can if emission rates exceed our assumptions) and also allow for ventilation reductions, and resulting energy savings, if concentrations are low. Until recently, it was impractical to consider direct contaminant control in residential (and many commercial) spaces due to the high cost and maintenance requirements for monitoring equipment. In the past couple of years low-cost sensors have been developed for some contaminants of concern – the greatest example of which is for particles. These sensors have been incorporated into low-cost (<$250 US) IAQ monitors. This has opened up the possibility of direct control of ventilation (and filtration systems) by sensing particles. However, it is important to evaluate these monitors to determine if their results are sufficiently good to control a ventilation system.