ATLANTA — ASHRAE’s newly-published residential IAQ standard removes the default leakage-rate assumption and also requires carbon monoxide (CO) alarms.
The 2013 version, ANSI/ASHRAE Standard 62.2-2013, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings, defines the roles of, and minimum requirements for, mechanical- and natural-ventilation systems and the building envelope intended to provide acceptable IAQ in low-rise residential buildings.
One of the biggest changes in the standard over the 2010 version is an increase in mechanical ventilation rates to 7.5 cfm per person plus 3 cfm per 100 square feet. This is due to the earlier removal of the default assumption regarding natural infiltration.
The 62.2 committee had previously assumed homes got a minimum of 2 cfm per 100 square feet, according to Don Stevens, committee chair.
“Because research shows houses have gotten tighter and apartments have always been tight, the 2013 edition drops this default assumption and calls for the entire amount to be provided mechanically,” he said. “The only exception is when single-family homes have a blower door test, then the predicted average-annual-leakage rate can be deducted.”
Another major change is a requirement for CO alarms in all dwelling units. CO poisoning leads to hundreds of deaths and thousands of injuries each year in homes, resulting from automobiles left running in attached garages as well as from portable generators, power tools, and heaters, according to Paul Francisco, committee vice chair. A small fraction of poisonings also result from failed central heating combustion appliances.
“Residents have very little ability to sense the presence of CO without detectors, unlike many other indoor polluting events,” he said.
Other significant changes include the removal of the climate limitations on pressurization and depressurization; specifications related specifically to multifamily buildings; and new calculations and weather data for estimating annual leakage based on a blower door test.
The cost of Standard 62.2-2013 is $58, $48 for ASHRAE members.
Publication date: 5/20/2013