ASHRAE Releases Revised Guidance Recommending Operation of ERV’s During an Epidemic

Posted 25 June, 2020 — News

On June 9th, ASHRAE published an updated guidance document, “Practical Guidance for Epidemic Operation of Energy Recovery Ventilation (ERV) Systems,” addressing concerns on the operation and use of energy recovery ventilators during an epidemic such as the current pandemic crisis.

The updated guidance states that “well-designed and well-maintained air-to-air energy recovery systems should remain operating in residences, commercial buildings and medical facilities during the COVID-19 pandemic. This is because maintaining at least normal Outdoor Air Ventilation rates, with proper temperature and humidity conditioning of the inside space, is important for maintaining health and combatting infectious bioaerosols.”


  • Normal Operation of the ERV Component is Recommended – “Changing the system operation settings without an effective understanding of the system likely will result in unintended consequences such as reduced Outdoor Air Ventilation rates or out-of-control indoor humidity conditions which may themselves favor the spread of viruses.” (pg. 6)
  • Recirculated Air from the Wheel or Plate is a Fraction of Total Recirculation Air  – “If the ERV exchanger is installed in a system where the outdoor air portion of the total system airflow is being processed by the ERV, but a portion of the Zone Return Air is being Recirculated back to the space as shown in Figure 1 (as are most AHUs and Unitary RTUs) then turning off the wheel would do little to improve the Zone Supply Air quality since the Exhaust Air Transfer rate associated with the wheel would be small compared to the Recirculation rate.” (pg. 6)
  • Increase Outdoor Air Ventilation and Operate ERV – “In epidemic situations it generally is recommended (see ASHRAE’s Building Readiness Guide) to increase Outdoor Air Ventilation and operate ERV, in order to increase dilution, while maintaining comfort conditions [6].” (pg. 16)
  • Clean & Maintain your Energy Recovery Wheel – “A dirty wheel can affect both flow and leakage.” (pg. 10). “Clean the exchanger surface as recommended by the manufacturer.” (pg. 9) “NOTE: Some exchangers can be washed, others cannot.” (pg. 9)

Source: ASHRAE, June 9, 2020 ASHRAE TC 5.5 Practical Guidance for Epidemic Operation of ERVs.