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The ASHRAE COVID-19 task force has been providing useful tips to our industry for helping to control the spread of the virus; and additional guidance is now available through some videos produced by Johnson Controls International (JCI). (Note that the views and positions taken by JCI are not necessarily those of HRAI).

JCI experts Matthew DeLoge, Rob Tanner and Jim Bogart have echoed some of the ASHRAE themes and added some new information that is worthy of consideration by HVAC professionals.

This includes:

  • HVAC systems move air through space and if particulates are aerosolized
    they can move the virus from one space into another.
  • Most systems are designed to bring in a small amount of outside ventilation air, however, we should consider increasing the outside air to better dilute pathogens, even if we might lose some humidity control.
  • Consideration should also be given to filtering systems, cleaning, and maintenance practices.
  • MERV Filters will not themselves trap the virus because it’s too small, however, it’s possible that the virus might attach itself to particles and those particles might be trapped by a MERV filter. Some other measures below are likely to do a better job.
  • One note that might seem counterintuitive is that filters actually perform more efficiently after they are somewhat loaded, ie. clean filters trap less particulate. HVAC professionals are cautioned that upgrading to a better MERV filter can cause a pressure drop. Your design engineer may be able to confirm whether the equipment will handle the load using a higher efficiency filter.
  • Ultraviolet Germicidal Irradiation (UVGI) is known to kill similar viruses and is expected to kill the virus that causes COVID-19, with a 99.9% success rate, when applied properly.
  • Bipolar Ionization (BPI) may be as effective as UV. It requires flooding a room with positive and negative ions, which react with VOCs, viruses, bacteria, and mold. It’s considered advantageous because it treats every surface in a room, including, for example, the bottom of doorknobs. In addition, the ions are said to coalesce particles, making them larger, so they can be trapped by filters (like MERV).
  • Despite our best intentions, we can make matters worse during maintenance procedures if we carelessly yank out filters, including MERV filters. The experts say the virus could be active on the filter and we could spread it in the room or onto our own bodies. The recommendation is to dress in good personal protective equipment and to bag and dispose of filters as if they contain infectious materials because they might.
  • Cleaning: In some cases, it has become a common practice to clean air handlers and other HVAC equipment with a pressure washer. If there is a virus on one of the surfaces this activity might aerosolize it, ie. making it airborne. An alternative is to clean by hand while wearing protective equipment or perhaps use the washer in a lower pressure setting.

The JCI videos mentioned can be found here: