Ventilation in Classrooms: Fall 2021

Ventilation in Classrooms Assigned by the University Registrar

The majority of classrooms assigned by the Registrar are equipped with mechanical ventilation systems, which provide a mix of outside air and filtered recirculated air. Ventilation systems in all buildings have been optimized to provide the maximum volume of outside air while maintaining comfortable relative humidity and temperature. Filtration in these mechanical systems has been upgraded when possible to remove 80 to 90% of respirable particles. Neither EHS nor Facilities are able to provide building- or room-specific details about ventilation work at this time.

For the few classrooms with no mechanical ventilation, portable units equipped with HEPA* filters have been placed by Facilities. These portable units are sized to provide several filtered air changes per hour.  Instructions and customer service information can be found on each unit, which should be run at low speed as frequently as possible.  If windows in these classrooms are operable, please use them to introduce additional outside air.  The Registrar can provide the list of classrooms that have been equipped with a HEPA unit.

*HEPA is a type of pleated mechanical air filter. It is an acronym for High Efficiency Particulate Air filter. This type of filter is designed to remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns (µm). The diameter specification of 0.3 microns responds to the worst case; the most penetrating particle size (MPPS). Particles that are larger or smaller are trapped with even higher efficiency. Source: Environmental Protection Agency

Ventilation in Classrooms Maintained by Departments

For the past 12 months, Facilities has adjusted ventilation systems in all campus buildings to pull in the maximum of outside air while maintaining temperature and reducing potential for microbial growth.  They have also upgraded filters to the most efficient level possible, given the physical configuration of the system (up to MERV-13).  Facilities will continue to respond to calls about temperature and humidity control in campus buildings, but no further improvements in ventilation/air exchange or filtration are indicated. 

For those classrooms with no mechanical ventilation managed at the department level, departments may choose to purchase portable HEPA filters that comply with the following guidance, if desired. Please note that this is completely optional on the part of the department and that the occupancy of these spaces does not indicate a need for additional HEPA filtration.

Portable HEPA Filter Guidance

  • Only purchase devices that have been tested for electrical safety by a nationally recognized testing laboratory (NRTL) .
  • Do not purchase units that generate ozone.
  • Select a unit that provides effective filtration by choosing:
    • one that is the right size for the space you will be using it in (this is typically indicated by the manufacturer in square feet).
    • one that has a high clean air delivery rate (CADR) for smoke (vs. pollen or dust), is designated a HEPA unit, or specifically indicates that it filters particles in the 0.1-1 um size range.
  • The unit should contain only a HEPA filter.  Do not purchase units that contain charcoal or any type of vapor removal filters. 
  • Contact Facilities at x8-8000 if you have questions about how use of the filter unit may affect the electrical capacity provided to the room.
  • Follow the manufacturer’s instructions when operating and maintaining the unit.
  • It is the department’s responsibility to maintain any HEPA units purchased. Do not request that Facilities maintain or change filters