ASHRAE has released an updated document titled "Practical Guidance for Epidemic Operation of Energy Recovery Ventilation (ERV) Systems." This guidance emphasizes the importance of continuing to operate energy recovery ventilators (ERVs) in homes, commercial buildings, and medical facilities amidst an epidemic, such as the ongoing COVID-19 pandemic.
The document highlights that maintaining normal levels of Outdoor Air Ventilation while controlling indoor temperature and humidity is crucial for health and reducing the spread of infectious aerosols.
Maintenance of Normal ERV Function
The instructions are based on maintaining critical air parameters for optimal health conditions
The guidance advises against altering system settings without comprehensive knowledge, as doing so might unintentionally lead to reduced Outdoor Air Ventilation or uncontrolled humidity levels, conditions that could facilitate the spread of viruses.
The instructions are based on maintaining critical air parameters for optimal health conditions.
Understanding Air Recirculation
A noteworthy point in the guidance is that the air recirculated by the ERV's exchanger is only a small fraction of the total recirculated air. Most air handling units (AHUs) and unitary rooftops units (RTUs) recirculate a portion of the Zone Return Air back into the space.
Thus, turning off the ERV wheel does little to enhance the quality of the Zone Supply Air since the exhaust air transfer rates linked with the ERV wheel are minimal compared to the overall recirculation rate.
Increasing Ventilation for Epidemic Situations
The guideline recommends increasing Outdoor Air Ventilation and operating ERVs during epidemic situations
The guideline recommends increasing Outdoor Air Ventilation and operating ERVs during epidemic situations.
This strategy aims to enhance air dilution while preserving comfortable indoor conditions, an action supported by ASHRAE's Building Readiness Guide. Such measures are suggested to decrease the potential spread of airborne diseases.
Regular Cleaning of Energy Recovery Wheels
Proper maintenance of the energy recovery wheel is also highlighted. A dirty wheel can negatively impact air flow and increase leakage. It is advised to clean the exchanger surface following the manufacturer's guidelines.
Some exchangers may be suitable for washing, while others may not, and adherence to specific cleaning instructions is crucial for optimal ERV performance.
