Fighting COVID-19 With Your HVAC System
Unfortunately, we have all been affected by this terrible virus. It has changed our everyday lives and how businesses manage their facilities. Many states are in the process of or developing plans to, reopen nonessential businesses. With that being said, it needs to be done safely.
Considering the virus is known to be transmitted through the air, it is believed that a properly maintained HVAC system can reduce the possibility of transmission from person to person. The reasoning behind this is supported by the fact that when a person infected with an illness coughs or sneezes, pathogens can be encapsulated within droplets of fluid and discharged into the air.
Smaller particles referred to as droplet nuclei can remain suspended. Infectious aerosols are a gathering of pathogen-laden particles in the air. Aerosol particles may deposit onto or be inhaled by a vulnerable person. HVAC systems supply clean air, contain contaminated air, and exhaust it outdoors, dilute the air with cleaner air from outdoors. Because of this, experts feel the risk of spread can be affected both positively and negatively by an HVAC system in a building.
What The Experts Are Saying
In April 2020, The American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) issued several statements to assist in defining guidance on managing SARS-CoV-2, the virus that causes COVID-19 disease (Coronavirus). The first was developed in response to incorrect opinions surrounding HVAC systems.
ASHRAE disagrees with advice not to run residential or commercial HVAC systems and emphasizes that keeping air conditioners on during this time can help control the spread of the virus. Here is the official statement regarding airborne transmission:
“Transmission of SARS-CoV-2 through the air is sufficiently likely that airborne exposure to the virus should be controlled. Changes to building operations, including the operation of heating, ventilating, and air-conditioning systems, can reduce airborne exposures.”
Here is a second ASHRAE statement regarding the operation of heating, ventilating, and air-conditioning systems to reduce SARS-CoV-2/COVID-19 transmission:
“Ventilation and filtration provided by heating, ventilating, and air-conditioning systems can reduce the airborne concentration of SARS-CoV-2 and thus the risk of transmission through the air. Unconditioned spaces can cause thermal stress to people that may be directly life threatening and that may also lower resistance to infection. In general, disabling of heating, ventilating, and air-conditioning systems is not a recommended measure to reduce the transmission of the virus.”
What It Means
Given these opinions, routine preventative maintenance (PM) and the changing of HVAC filters have never been more important. PMs paired with other strategies such as temperature and humidity distribution control and ultraviolet germicidal irradiation (UVGI) are believed to help reduce virus transmission while removing other air contaminants. While ventilation can’t address all aspects of infection spread, it does impact the circulation of infectious aerosols.
Some Recommendations Moving Forward:
- If installing/designing a new system, whether a high-risk facility or not, the mitigation of infectious aerosols needs more focus than in the past. Also, make sure there are cleaner airflow patterns.
- Increase PM frequency. At a minimum, a quarterly inspection should be taking place and paired with monthly filter changes if possible.
- Enhance filtration and use higher minimum efficiency reporting value (MERV) filters, well over code minimums. Everyone should be using filters rated between 13-16 if the systems support them.
- Clean coils at every service and chemically clean once annually.
- Increase outdoor air ventilation (open outdoor air dampers to 100% as conditions permit).
- Keep systems running as much as possible, preferably 24/7.
- Verify the room sensors are calibrated and working properly.
- Ensure room controllers and monitors are working and communicating with supply and exhaust airflow valves.
Medical Facilities Should Consider The Following:
- Exhaust toilets and bedpans.
- Maintain temperature and humidity as applicable to the infectious aerosol of concern.
- Maintain negatively pressurized intensive care units and rooms with infectious aerosol concerns.
- High-level exhaust to all patient rooms.
- Use of UVGI.
- Increase the outdoor air change rate.
As people around the globe navigate the rapidly evolving novel COVID-19 pandemic, it is extremely important to educate yourself as frequently as possible. We are learning something new every day and it is our responsibility to make sure we take all the necessary precautions to keep employees and customers safe. If you haven’t had an HVAC PM completed in the past 3 months, it’s very important to get one scheduled ASAP.
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