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ASHRAE issues correction on changes to addendum r to ANSI/ASHRAE Standard 62.1-2007 on ventilation for IAQ

ASHRAE issues correction on changes to addendum r to ANSI/ASHRAE Standard 62.1-2007 on ventilation for IAQ

August 11, 2010

Earlier today, ASHRAE distributed a news release, ASHRAE Proposes Mechanical Ventilation Requirements for Naturally Ventilated Buildings. This release contained erroneous information about proposed changes in addendum r to ANSI/ASHRAE Standard 62.1-2007, Ventilation for Acceptable Indoor Air Quality. Requirements regarding mechanical ventilation for naturally ventilated buildings are actually included in addendum n, which has completed public review and will be included in the 2010 version of Standard 62.1, which is expected to be available in spring 2010. 

The proposed changes open for review in addendum r focus on the IAQ procedure, which is a performance-based approach to compliance with the standard, and allows for designers to adjust the ventilation requirements for a building or space based on performance factors which are unique to the building.  These performance factors might include the use of low-emitting materials in the space or the known presence of a contaminant source.  The first public review draft of Addendum r removed a method of complying with the IAQ procedure by designing the ventilation system in the same way as an existing successful building.  Based on public review comments, this approach was put back into the standard, but with new restrictions.  These include a requirement that a mass-balance analysis of the building's air quality be performed in every case.  This will require that the designer identify contaminants of concern for every building or space where the IAQ procedure is used, along with associated concentration or exposure limits.


Working to help ensure the quality of indoor air of naturally ventilated high-rise residential buildings, ASHRAE is proposing that mechanical systems be required for such building types.

Proposed addendum r would require that most buildings with natural ventilation have mechanical ventilation systems installed that are capable of meeting the requirements of the standard’s Ventilation Rate Procedure.  The mechanical system is to be used when windows are closed due to extreme outdoor temperatures, noise, security concerns, etc. 

The proposed addendum is open for public review from Sept. 11 until Oct. 26, 2009. ANSI/ASHRAE Standard 62.1-2007, Ventilation for Acceptable Indoor Air Quality, sets minimum ventilation rates and other requirements for commercial and institutional buildings. 

“Most buildings using natural ventilation in the United States are high-rise residential buildings that often have no form of outdoor air intake other than operable windows,” Roger Hedrick, Standard 62.1 committee chair, said. “This results in buildings with inadequate ventilation, because the occupants then leave the windows closed in order to run the air conditioning, keep out noise, etc. The committee felt it needed to strengthen the existing prescriptive requirements for natural ventilation to improve their corresponding IAQ benefits.”

Also open for public review during the same time period is proposed addendum g, which would add information on using demand controlled ventilation systems. Coverage of DCV systems in the standard is not yet comprehensive, but this addendum provides needed clarifications on the issue.  

To view a copy of the addenda open for public review, go to www.ashrae.org/publicreviews. Copies of public review drafts are only available during public review periods.


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