Homes and workplaces are full of potential contaminants ranging from viruses to VOCs (Volatile Organic Compounds) to common dust. Proper ventilation and the exchange of air is the best way to reduce the presence of these contaminants, maintaining a healthy living and working condition. Air Changes Per Hour (ACH) is a measure of air volume that can be added/removed from a space in a given hour.
Other air purification systems will quote areas of square footage covered but that doesn’t speak to the number of air changes that a system can do in an hour. The more changes per hour, the more quickly the air is purified, and the more quickly contaminants are removed. A machine created for the home may only change the air 1x per hour, which isn’t enough for places like conference rooms where people are congregating.
It might seem complex, but the calculation is simple: Air Changes Per Hour = Volume of Air Flow in cubic feet per hour (CFMx60) / cubic feet of the area.
In general, an ACH of 5 means your air is being cleaned every 12 minutes. You should be aiming for 3-5 air changes per hour. A solution with superior filtration and more air changes per hour is going to do a more effective job at maintaining quality of air. According to Harvard Schools for Health, they recommend utilizing True HEPA filtration in addition to HVAC systems to ensure proper ventilation and filtration.