Mitigating solutions to help fight the COVID-19 crisis from an engineering perspective, now and in the “New Normal” afterwards.
In above video, I reveal lots of insights on our existing Heating Ventilation and Air-conditioning (HVAC) systems and options on adapting the operation of these systems of critical buildings like hospitals, nursing & elderly homes, prisons, etc. in order to mitigate the risk of transmission of the COVID-19 virus through HVAC systems in the midst of this pandemic and for the “new normal” afterwards.
Studies have shown that the COVID-19 virus, which is only .125 micron in size, can stay airborne longer than initially thought.
The American Society of Heating Refrigeration and Air-conditioning Engineers (ASHRAE), which is an authority and the leading organization in the world on regulations and standards on heating, refrigeration and air-conditioning, has looked several times in the past into the transmission of airborne diseases like influenza, measles, tuberculosis and viruses through the HVAC system and has now come up with the following statement on COVID-19 and HVAC systems on April 20, 2020.
“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.“
This statement is also supported by recent lab tests, which show that tiny particles from a sneeze can travel over a distance of 10 feet and more. These tests have not even taken into consideration the amplifying effect of higher air velocities in rooms, draft and the pumping effect of certain opening doors etc.
ASHRAE is clear about the likelihood of exposure to the COVID-19 virus and the risk of infection through the HVAC system and they urge the importance of adapting the operation of our buildings and HVAC systems to lower the risk of infection for its inhabitants.
For this reason we are looking at different options to adapt the HVAC systems in critical buildings like hospitals, nursing & elderly homes, prisons, but also in schools, offices and all other commercial systems, starting with things we can do right now without major technical and engineering interventions.
Some first immediate relatively easy-to-implement actions that can be considered include, increased servicing of your HVAC systems and making sure they function properly, increasing the amount of fresh air into the existing HVAC unit, by adjusting the fresh air intake of the unit. Some additional actions that are still easy to implement, yet do require a little more effort include, creating a more laminar air flow in the room with COVID patients by lowering the airspeed from the supply grills, enhancing filtration with HEPA filters and installing UV lamps. These last two options with HEPA filters and UV lamps, are very effective and can be considered for all existing HVAC systems in critical buildings, especially now during the COVID-19 pandemic and for the “new normal” afterwards.
There are more options and adaptations we can do to our HVAC system to lower the risk of transmission of the COVID-19 virus for building inhabitants, although these do require more technical and engineering intervention. Two interesting options to start with include 1) changing the air pattern in the room by lowering the returns grills for critical rooms and 2) installing fan filter units to increase the amount of air changes in the room, as well as helping to create a more laminar flow in the room.
Although the latter two options provide a good starting point, especially for high risk spaces, it is advisable to step up the level of effectiveness even more by extensively increasing the amount of fresh air with additional fresh air units in the existing HVAC systems.
Studies have shown that a higher percentage of fresh air in buildings can effectively dilute the polluted inside air considerably, leading to a far lower risk of infection with infectious diseases that are airborne.
Over the years, ASHRAE has developed documentation to support the importance of introducing more fresh air in buildings, to the point of rating this solution with a very high level of effectiveness. Following are engineering control strategies proposed by ASHRAE for mitigating the transmission risk of airborne infectious diseases like measles, influenza and other viruses, etc., namely:
- dilution ventilation (i.e. high percentage of fresh air)
- in the room flow regimes (i.e. focus on air patterns and laminar air flow)
- differential room pressurization (i.e. negative pressure in rooms with COVID-19 patients)
- personalized ventilation
- source capture ventilation
- central system filtration (i.e. with HEPA quality MEV13 to MERV 17 filters in ducts, air-handlers & HVAC units)
- local air filtration (i.e. with HEPA quality MEV13 to MERV 17 filters in patient’s rooms)
- In-room and duct Ultra Violet Germicidal Irradiation (UVGI) (i.e. UV lamps in the air ducts, upper room and in-room mobile units)
Finally, ASHRAE holds a strong position that engineers play a key role in reducing disease transmission that occurs in buildings.
In the case of the novel COVID-19 corona virus, where there is substantial evidence that tiny particles remain airborne for longer periods of time, the increased fresh air approach is also highly applicable and effective for mitigating the risk of transmission of this virus.
For a more in-depth analysis on the different options of mitigating the risk of transmission of COVID-19 in our buildings, please refer to the above video included in this blog.
As a final note it is important to emphasize that although mitigation the risk of transmission of COVID-19 through adapting the operations of our HVAC systems can play an important part in lowering the risk of infection for inhabitants, it will not eliminate in itself the risk totally. Non-HVAC actions like, wearing PPE’s (Protective Personal Equipment), frequently cleaning surfaces and washing hands with soap, social distancing, etc. are crucial elements that are the first line of defense against the COVID-91 virus.
In closing, I am offering my voluntary support during this COVID-19 pandemic to engineering teams in critical buildings and high risk spaces. Feel free to reach out to me and I would be happy to look at your drawings and think along with you. See my contact information on my website https://blue-engineers.com/contact/
Finally, I would like to wish you a lot of strength in this difficult period, be safe and stay well.
Erney Errol Pinas
Holistic Engineer, inventor & entrepreneur with 30+ years international experience in renewable energy & indoor air climate
PS. Following is a link to my first blog on COVID-19 https://blue-engineers.com/covid-19-1/