April 29, 2020 - HVAC
By Saagar Patel
The HVAC system can help reduce risk of transmission of an airborne virus. The transmission associated with coughing, sneezing, and shouting can produce small airborne particles if connected to another host (such as dust). To date, there are no known COVID-19 cases that have resulted from this sort of airborne transmission. However, per ASHRAE, HVAC systems can change operation in a variety of ways to help alleviate these concerns:
During times of low occupancy, increase the overall ventilation rate by:
• Going to full economizer mode to increase outside air delivery and eliminate any recirculation.
• Increasing outdoor air damper positions.
• Disabling any demand control ventilation.
Increasing hours of operation of HVAC systems will provide additional time for ventilation dilution.
Steps include:
• Upgrading to higher filter ratings on central air distribution systems
• Using portable air purifying (HEPA or UVGI) systems for high-traffic areas. ASHRAE’s position document suggests that temporary air purifiers in high traffic areas may be beneficial; however if the existing air change rates are high (6 to 10 per hour) portable air purifying system may not have much impact.
While a building's HVAC can assist in reducing the spread of a virus, facility managers should also review the best practices shared by CDC and ASHRAE, which include:
• Hygiene and social distancing.
• Increasing frequency of surface cleaning and disinfection. CDC has a list of cleaning products to consider.
• Increasing hand sanitation stations.
• Encouraging bottle filling instead of use of water fountains and cleaning the bottle filling station frequently.
• Consider shutting down food preparation and warming areas.
• Clean known contaminated areas.
Saagar Patel is the Energy + Eco Studio leader at Environmental Systems Design.
