Optimizing Indoor Air Quality with Energy Recovery Ventilation (ERV) Technology


Fresh air is the #1 requirement for a healthy indoor environment. According to the EPA, people spend 90% of their time indoors, breathing air that is likely 2 to 5 times more polluted than the outdoor air.  The use of fresh, filtered outdoor air to achieve maximum dilution of all indoor pollutants is therefore crucial to our health and well-being.

Building codes require minimum ventilation rates intended to satisfy 80% of building occupants. However, multiple studies have shown that ventilation rates above these minimums significantly improve occupant health, productivity and cognitive abilities.  For example, each doubling (2x) of the minimum ventilation rate results in a 50% reduction in the concentration of all constant source air pollutants evenly mixed within the space.  Learn more on the dilution principle. In short – More fresh air equates to lower health risk.

Creating a healthy indoor environment is one part of the critical equation. Counter balancing increased outdoor air ventilation rates with an energy efficient, economically affordable ventilation system is the other equally important part of the equation.


Increased ventilation rates place new demands on HVAC equipment and on building operating budgets. Energy recovery ventilation (ERV) technology reduces the load on the system by taking advantage of energy already paid for to heat, cool, humidify or dehumidify the indoors. Instead of wasting this energy during the ventilation process, ERV’s recycle up to 80% of this free energy to precondition the incoming air. Energy recovery ventilators do this with exceptional efficiency and are the leading technology for achieving energy conservation while ventilating for health and comfort.

Recirculated air sources


  • ERV’s should operate a minimum of 2 hours before start of building occupancy through 2 hours after planned occupancy to maintain adequate dilution rates for occupants.
  • Increase outdoor air ventilation rates if possible, to maximize the dilution effect on all indoor pollutants, consistent with CDC guidance.
  • Do not disable ERV systems without a complete understanding of system operation. This could result in unintended consequences such as reduced outdoor ventilation rates or loss of indoor humidity control which may favor the spread of viruses.
  • Do not bypass ERV components when serving areas designed with recirculating HVAC systems. Exhaust Air Transfer Ratio’s (EATR) are insignificant compared to recirculated air volumes in other areas of the HVAC system.
  • If an energy recovery wheel has been out of operation for an extended period, follow Airxchange®’s instructions for cleaning/disinfecting the component.
  • For a full paper outlining Energy Recovery in a pandemic, review our White Paper “Energy Recovery Best Practices During Pandemic”.

Additional Resources

For additional info on energy recovery components, please refer to the following webinars and documents:

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

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Understanding Energy Recovery Component Leakage Webinar

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Practical Guidance to Restarting and Operating Energy Recovery Systems Webinar Series Part 1: ERV operation during pandemic

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Practical Guidance to Restarting and Operating Energy Recovery Systems Webinar Series Part 2: Energy Recovery Inspection and Evaluation

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Practical Guidance to Restarting and Operating Energy Recovery Systems Webinar Series Part 3: Cleaning of Airxchange® wheels

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Energy Recovery Best Practices During Pandemic White Paper

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Guide to Cleaning Airxchange® Wheels

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