Reducing Coronavirus Transmission Rates - An HVAC Response
With the CDC expanding face mask recommendations last week, it seems there is an acknowledgement that there is a strong possibility coronavirus can be spread via airborne transmission.
So now what?
As a mechanical engineer in the HVAC industry, ensuring the health and safety of indoor air is a part of my job. Here is a quick summary of steps building operators can take right now that reduce the risk of airborne transmission.
1. Increase Ventilation: If you have a system that recirculates air, increase the outside air to as much as 100% of the supply air. Disable demand controlled ventilation. Consider increasing the operating hours of your systems. These steps will keep the building well flushed and reduce the amount of potentially contaminated air recirculating back into the building.
2. Adjust Relative Humidity: Most systems with humidifiers are designed for a minimum relative humidity setpoint of 30%, however there is strong evidence to suggest that increasing this setpoint to 40% reduces infection transmission. If your building has a humidifier, consider revising the setpoint. If your building is in a humid climate, considering adjusting your cooling setpoints to reduce dehumidification.
3. Increase Filtration: Ensure your central air handling systems have MERV 13 filtration or higher (HEPA) within the limitations of your fan systems. Alternatively, consider in-room portable air cleaners with HEPA filtration.
It should be noted that these steps will result in a temporary energy penalty and only apply to facilities that remain open. For facilities that are closed due to stay-at-home orders, it is recommended to turn HVAC down or off entirely to save energy and money.
These thoughts incorporate recommendations from multiple resources. See below links for additional information.
Mechanical Engineer and Team Builder
4 年There is strong evidence that proper humidity levels can improve the human response to viruses. However, please be careful offering the owners and operators of buildings in cold climates the advice to simply increase their indoor humidity to 40%. Unless the building envelope has been designed to handle that indoor humidity level operating at 40% RH has the potential to cause moisture problems within the envelope assembly. This can lead to real and long term problems with the building. Mold growth and permanent envelope component degradation are potential outcomes. Each situation needs to be evaluated independently by a qualified HVAC professional to ensure an appropriate long term result.
Owner, Kehoe Equipment Ltd.
4 年All good ideas Sarah! Pathogens infectivity is high when indoor RH is less than 40% which leads to greater aerosol transmission, evasion from surface cleaning through resuspension and an increased survival and virulence of pathogens. Folks - get your humidifiers working and your set points between 40-60%! #Humidity #DriSteem #ASHRAE
Vice President of Sales at ATS Automation
4 年Excellent summary Sarah. Thanks for posting!
Associate Broker at Russ Lyon Sotheby's International Real Estate
4 年I love the simplicity of these steps. Include cold plasma air purification and you will increase your existing filter capability by up to 300% - and neutralize Viruses as well.
retired
4 年something like the AEMC 1510 temperature/humidity/CO2 monitor can tell you if you are achieving the desired results. https://www.aemc.com/products/environmental-testers/air-quality-logger-1510 it can take spot reading or left insitu to log data over time