Maintaining the Quantity of Outside Air for Good IAQ

  August 6, 2012

As indoor air is often more polluted than outside air, maintaining a proper mix of outside air in your facility is key to flushing out toxins and preserving good indoor air quality. If your HVAC system cannot deliver sufficient outside air or properly condition the outside air, consider retrofitting your system.

Depending on the type and age of your HVAC system, there are many modifications you may be able to make that will improve its performance. The following retrofit options may be useful. You could add separate outside air fans to each air handling unit, use a make-up air unit or use energy recovery equipment.

Another operations step you can take to protect indoor air quality is making sure that outside air dampers are set and controlled properly.

Do not rely on fixed outdoor air dampers or settings last established at the time of construction or renovation.

Periodically check that the outdoor air dampers can open and that linkages, controls and related mechanisms are functioning. For constant air volume systems, check outdoor air flow and reset the damper position at least every few years or as occupancy changes.

Fixed outdoor air damper positions cannot ensure sufficient ventilation nor meet the ASHRAE Standard 62 Ventilation Rate Procedure as it applies to variable air volume (VAV) systems. Consider air flow monitoring that is integrated into your HVAC system to maintain the desired VAV ventilation air flow.


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