ANSI/ASHRAE Standard 62.2, "Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings," is an indoor air quality standard developed solely for residences. Addenda 62.2a and 62.2b were approved for publication at ASHRAE's 2004 Annual Meeting. The addenda are the first for the standard, which was published in 2003.
Addendum 62.2a removes combustion appliance backdrafting test requirements from the standard. The test was based on the best industry-accepted method found in the National Fuel Gas Code, but questions arose about its application to solid-fuel burning appliances, according to David Grimsrud, chair of the Standard 62.2 committee. There also was concern about it not being possible to perform the test until the home is completed, opening the potential for having to perform remedial balancing at a difficult stage of construction and sale.
Although the proposed addendum eliminates the test requirements, it sets an upper limit of exhaust flow to 15 cfm/100 square feet when natural-draft combustion appliances are present. It requires designers or installers to address the level of depressurization at a stage where the problem can be fixed more easily, Grimsrud said.
Addendum 62.2b changes the terminology "severe cold climate" to "very cold," which is now defined as one that has more than 9,000 65 degree F degree-days.
"This makes the standard's climate definitions consistent with the proposed revisions to the International Code Council climate zone definitions, which will simplify implementation of Standard 62.2 into code," said Grimsrud.
The primary impact of the change is to remove the Minneapolis-St. Paul metropolitan area from the "severe cold" climate category. As a result, this area no longer falls under the restriction in the standard forbidding the use of mechanical supply systems exceeding 7.5 cfm/100 square feet. The change has some effect on smaller urban areas as well.
Published addenda to ASHRAE standards are available for free at www.ashrae.org.
Publication date: 08/02/2004