Filtration and COVID-19
A typical Filtration system in an air handling unit has a MERV (Minimum Efficiency Reporting Values) of 8 which is effective in filtering out typical particles found in a commercial building's indoor air environment. But now with the transmission of airborne viruses such as COVID-19 in buildings we need to look at all our HVAC systems and modify them as much as possible to reduce possible transmission between occupants in a space.
One of the most effective ways of reducing the transmission between occupants is to increase our building's HVAC systems filtration to a minimum MERV13 filter which is capable of filtering much smaller particulates. This is an extremely effective way of significantly reducing the spread of viruses within a space. But here is the issue that most business owners face when making these critical decisions on our health and safety. The filtration salesperson will show you how small the particles a MERV13 filter can remove and how wonderful and clean our air will be and how much we will improve the indoor air quality (IAQ). What they fail to tell you is that by filtering out finer particles, we will use more fan power to push the air through the finer mesh. Often the fan's output will be reduced significantly resulting in less filtered air being delivered to the building's space. The net result of this is an increase in the transmission of airborne viruses between building occupants. This becomes a balancing act to ensure the building maintains a minimum acceptable airflow and provides maximum filtration. Some of our options are to try and maintain a minimum of 6 Air Changes of Treated air within the space by selecting a filter between MERV8 and MERV13, increasing our fan speed, and when all else fails to install UVC-Lights before the existing filters which will have the same effect as the MERV13 filtration system without the added fan power requirement.
In the end, it's best to hire an HVAC engineer who specializes in Airborne Disease transmissions and who can design, specify and commission your retrofit to reduce the probability of infectious diseases within a space.
Atlabach Consulting is a world leader in providing Computational Fluid Dynamic Modelling of virus transmissions within a building along with Probability Of Infection Analysis to fully understand the health and safety of your occupants currently and afterward. www.atlabach.com