Use of Filtered Recirculated Air Compliance Proposed

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Compliance Path based on Use of Filtered Recirculated Air Proposed for ASHRAE Residential IAQ Standard

ATLANTA – A new optional credit for improving filtration combined with ensuring sufficient air flow through filters is being proposed for ASHRAE’s residential indoor air quality standard.

ANSI/ASHRAE Standard 62.2-2013, Ventilation and Acceptable Indoor Air Quality in Residential Buildings, is the only nationally recognized indoor air quality standard developed solely for residences.  It defines the roles of and minimum requirements for mechanical and natural ventilation systems and the building envelope intended to provide acceptable indoor air quality in residential buildings.

Eight proposed addenda to Standard 62.2-2013 are currently open for public comment. To comment or learn more, visit

Among them is addendum k, which is open for public comment until Oct. 4, 2015. The addendum would create a compliance path based on the use of recirculated air that has been filtered to reduce exposure in the building interior to particulate matter not exceeding 2.5 microns.

“These particles (PM2.5) have been found to be one of the most important indoor contaminants from a health perspective,” Paul Francisco, 62.2 committee chair, said. “This change would provide an optional credit for having improved filtration combined with ensuring that sufficient air flowed through the filter. This would be the first time the standard has focused on a specific contaminant.”

In addition, addendum v is open for public review until Oct. 19. The addendum sets out requirements for non-continuous ventilation. Whereas the standard has included an option for intermittent ventilation, this proposed change provides calculation procedures for a boarder range of potential operation schedules. It also contains a limit on how much contaminants can increase over a short term due to non-continuous operation to ensure this type of operation does not result in periodic excessive contaminant levels, according to Francisco.

Other addenda are scheduled for review until October 4, 2015 are:

  • Addendum o. The committee approved a proposal to change references to “whole-building” or “whole-house” ventilation to “dwelling unit” ventilation in the main body of the standard. This proposed changed ensures consistency in Normative Appendix A (Existing Buildings).
  • Addendum p would clarify the requirement in Section 7.2.2 (Demand-Controlled Local Exhaust Fans) that fans have at least one speed setting meeting the minimum required exhaust airflow rate where the corresponding sone rating is 3 or less. Currently, the language in this section would permit any fan with a high speed setting exceeding 400 cfm to be exempt from the sone requirement, even if operating on a lower speed setting. Closing this loop hole will ensure that occupants that have typical sized range hoods will have at least one speed setting rated ≤ 3 sone.
  • Addendum q adds an alternative combustion safety testing method based on performance in lieu of the prescriptive requirements that were the sole basis previously.
  • Addendum r would provide guidance on this topic while aligning the language with the latest draft of BSR/RESNET/ICC 380, “Standard for Testing Airtightness of Building Enclosures, Airtightness of Heating and Cooling Air Distribution Systems, and Airflow of Mechanical Ventilation Systems.”
  • Addendum s provides a mechanism for accounting for the differences between balanced and unbalanced ventilation. Standard 62.2 has not previously distinguished between balanced and unbalanced ventilation, despite it being well-known that these interact with natural infiltration in different ways to produce different overall air exchange rates.
  • Addendum u adds an alternative method to reduce transfer air in existing buildings. The compartmentalization requirement in the existing standard is extremely difficult and cost-prohibitive to meet for many existing buildings. While this is a desirable target, an alternative for existing buildings to meet the standard with reasonable effort is needed.

ASHRAE, founded in 1894, is a global society advancing human well-being through sustainable technology for the built environment. The Society and its more than 54,000 members worldwide focus on building systems, energy efficiency, indoor air quality, refrigeration and sustainability. Through research, standards writing, publishing, certification and continuing education, ASHRAE shapes tomorrow’s built environment today. More information can be found at

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