COVID-19 Recommendations for HVAC Systems

This page was last updated on April 20, 2021

While many businesses in Texas resumed normal operation in March 2021 after the state mask mandate was lifted, it is still important to improve the air quality and filtration of your offices and facilities to reduce the risk of spreading the coronavirus.

The CDC (Centers for Disease Control and Prevention) recommendations include the following for office buildings:
https://www.cdc.gov/coronavirus/2019-ncov/community/office-buildings.html

1. "Increase circulation of outdoor air as much as possible."
   
   We can adjust your HVAC system's dampers to bring in more outside fresh air. The downside to this adjustment is that the hot and often humid climate in Texas will make your HVAC systems run longer and harder to cool and remove the moisture from this air.
   
   This will likely result in higher energy costs, more wear on your HVAC systems and components, and replacing air filters more frequently as these filters will clog up faster with more outdoor dust and airborne particles compared to the relatively clean air that is recirculating within the building.
   
   
2. "Increase air filtration to as high as possible without significantly diminishing design airflow."
   
   Most commercial HVAC systems use MERV 8 or 10 pleated filtration, and ASHRAE recommends upgrading to MERV 13 filtration where possible (https://www.ashrae.org/technical-resources/filtration-and-disinfection-faq). This can often be done without having to make any design changes to your existing commercial HVAC systems or ductwork.
   
   A MERV 13 filter is effective at stopping the spread of viruses to other areas in the building and is quick to implement. These filters trap the small particles that aren't caught by a MERV 10 or 11 filter, and may need to be replaced more often as they are catching more airborne particles than a lower rated filter.
   
   Some customers have inquired about MERV 11 filters, but these are not effective in catching virus particles such as COVID-19 (see the chart below).
   
   We also offer higher rated filtration, including MERV 14-16 filters (box or mini-pleat style) and HEPA filters. These filters are very efficient but significantly reduce airflow, so they are only used in systems originally designed to handle this pressure drop.
   
   

	MERV
	8	10	11	13
Pollen	✔	✔	✔	✔
Dust / Lint	✔	✔	✔	✔
Dust Mites	✔	✔	✔	✔
Debris	✔	✔	✔	✔
Pet Dander		✔	✔	✔
Mold Spores		✔	✔	✔
Vehicle Fumes / Smog			✔	✔
Smoke *			✔	✔
Bacteria				✔
Viruses				✔
Allergens				✔




* An activated carbon filter is used to remove odors



3. "Consider using ultraviolet germicidal irradiation (UVGI) as a supplemental technique to inactivate potential airborne virus"
   
   Ultraviolet (UV) lamps, when properly installed and maintained have proved to reduce infections from other viruses and is therefore likely to reduce infections from the COVID-19 virus as well. These lamps are quite popular, but unfortunately we have found that some UV lamps are being installed incorrectly.
   
   UV lamps should never be placed in close proximity to a filter, as the UV light will cause the filter material to deteriorate. The pictures below show what we found in one system. The correct placement for this system is on the other side of the coil, treating the air after it has been filtered.
    




Note: This is not a UV lamp we installed, but one we found installed incorrectly by someone else.