How HVAC can help safeguard against virus transmission

Ventilation systems are part of daily life at home, the office, and nearly all commercial stores. Concerns have been raised about the role HVAC systems play in the transmission of airborne viruses.

According to the Centers for Disease Control (CDC), many common viruses are thought to spread from person to person through respiratory droplets that are produced when an infected person coughs, sneezes, talks, sings, etc. These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs, which is more likely when people are in close contact with one another (within about 6 feet).

Although numerous articles have been published on commercial building air handling systems, the author is unaware of any reports of space to space virus transmission. That being said, ventilation with outside air and proper filtration are important safeguards for the reduction of said transmission.

Recirculation only systems with no, or very limited, outside air can become a large threat. Some real-world examples of these high-risk environments include:

  • Wall-mounted “duct-less” air conditioners often seen in restaurants
  • Window air conditioners
  • Supplemental fans being used within an enclosed environment

Here are a few suggestions to help safeguard against virus transmission:

Filtration – Know Your MERV Number:

The filters that are specified for typical commercial buildings are a MERV 8, which doesn’t help much for the reduction of viruses. The better option is a MERV 13, a filter rated for virus reduction. Some systems, especially residential ones, can have lower airflow rates with these higher MERV numbers though, so capacity could be reduced using these anti-virus varieties. These filters should be changed frequently, with 90 days of service being the maximum period before replacement.

Amp up Your Air Cleaning Technology:

Healthcare facilities, health clubs, airports, and offices can also help stop the spread of  viruses by using added protection within their HVAC systems including:

  • Ultraviolet C (UV-C) lighting systems – UVC exposure eliminates microbial organisms such as bacteria and viruses by altering the structure and the molecular bonds of their DNA.
  • Bipolar ionization systems – Bipolar ionization technology releases charged atoms that attach to and deactivate harmful substances like bacteria, mold, allergens, and viruses.

Specific engineering design is required for the proper use of these technologies.

ASHRAE’s Occupancy Guides can also be referenced to deal with functioning buildings. Further ASHRAE commercial building guidance indicates that periodic flushing of ventilation systems with outside air during off-hours, when occupants leave the space, should be a new ventilation strategy.

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© 2020 The Hartford Steam Boiler Inspection and Insurance Company. All rights reserved. This article is for informational purposes only and is not intended to convey or constitute legal advice. HSB makes no warranties or representations as to the accuracy or completeness of the content herein. Under no circumstances shall HSB or any party involved in creating or delivering this article be liable to you for any loss or damage that results from the use of the information contained herein. Except as otherwise expressly permitted by HSB in writing, no portion of this article may be reproduced, copied, or distributed in any way. This article does not modify or invalidate any of the provisions, exclusions, terms, or conditions of the applicable policy and endorsements. For specific terms and conditions, please refer to the applicable endorsement form.

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