Campus HVAC Systems and COVID-19

CDC (Centers for Disease Control) and ASHRAE (American Society of Heating, Refrigeration, and Air Conditioning Engineers) experts are stating that the COVID-19 virus typically transmits via respiratory droplets through close person to person contact. This drives all the recommended human behavior guidance for reducing transmission such as social distancing, wearing masks, personal hygiene, staying home while sick, and decreasing occupant densities. These experts state that airborne transmission is unlikely, thus it is unlikely that the virus is spread through HVAC systems. Following these recommended guidelines greatly reduces the already low risk of HVAC systems causing spread. Please note that HVAC systems cannot be relied upon to compensate for not following human behavior guidance.

• Please note that all information included herein applies to all buildings on campus—including residential, academic, administrative, and athletic facilities.
• Facilities Operations are maintaining all HVAC systems on campus, including confirming existing air distribution systems are working properly and exchanging air properly throughout our facilities.
• HVAC systems and controls are maintaining appropriate space temperature best suited for human comfort. This is the priority of a HVAC system, and it is not easily maintained with major modifications to the systems. Instead of modifying the system, best practice guidance is to confirm that existing systems are working effectively.
• We are also confirming regular filter maintenance on every central air system on campus. Every central air system on campus operates with the recommended MERV filter rating capable of filtering out virus size particles (rating range of MERV-6 through MERV-14). Additionally, even if a virus particle becomes airborne, it is unlikely the virus particles are able to travel the distance through the return plenum or ductwork, still remain active while mixing with ventilation air, and not be caught by existing MERV filter systems to continue to pass through the supply air distribution back to the facility.
• All of our facilities are designed to operate with some type of ventilation air, which will be maintained during reopening operations.
• We are adjusting and confirming that all of our central HVAC systems will be enabled to filter and circulate air during all occupied hours of the building, as well as for a period of time before and after occupied hours to “flush out” the facilities. For academic facilities that previously operated on a time-of-day occupancy schedule, those time schedules are being removed to ensure central air systems will be under constant operation. The 24/7 operation of HVAC systems across campus ensures constant air exchange for a period of time before and after anticipated occupied hours of the facility.*

*During the extended winter break of November 25 through January 24, some HVAC air systems operations will be modified to incorporate daily shutdown schedules to better represent true usage of campus spaces during the break and provide an opportunity for energy savings. The setback schedules will be in place across the majority of air systems at most campus facilities. Upon campus reopening on January 25, it is expected that all HVAC air systems return to 24/7 operation.

• All campus facilities are designed to operate with some type of mechanical or natural ventilation air, which is being maintained upon reopening. Additionally, by downsizing and minimizing classroom and common space occupancy to maintain social distancing guidelines, it actually inherently results in increased air changeover per occupant in the space. In engineering design, mechanical systems are required to provide enough ventilation for maximum occupancy of a given space, thus by reducing maximum occupancy, the existing HVAC system is likely to provide excess ventilation per occupant without adjusting HVAC system operation or control. Overall, reducing the occupant capacity of a building or space effectively increases the HVAC system performance.
• Jordan Hall East Wing and Old Pharmacy are areas on campus that operate with indirect mechanical ventilation and/or natural ventilation. For these facilities, operable windows can be opened when spaces are occupied but are encourage to be closed during unoccupied times.

Air changes per hour (ACH) is defined as the volume of ventilation air that is supplied and removed from the room every hour. The ACH rate varies across campus based on space use type. Laboratories and large event spaces are typically supplied with 6-12 ACH, and office and general classroom spaces are typically supplied with 2-6 ACH, which is consistent with engineering design standards.

The University does not prohibit portable space heating and cooling units, but given COVID-19, the use of high-speed fans should be avoided especially in common areas with the potential of blowing across multiple workstations.

Because of the increased pressure drop associated with HEPA filters, upgrading to HEPA filters is not recommended in most existing HVAC systems. The existing HVAC systems on campus are not capable of running effectively, supplying appropriate airflows, and maintaining appropriate space temperature and humidity with the increased pressure drop of a HEPA filter. Additionally, other than their typical use in cleanrooms in healthcare, HEPA filters are not a common option in commercial facilities. Instead, all central air systems on campus utilize the highest MERV rating the system is capable while still running effectively, which is in the range of MERV 6–MERV 14.

Experts are not supporting any proven protection from the transmission of COVID-19 virus through the use of an additional air purifier in the space.