The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) has approved a change to its residential ventilation standard to encourage home retrofits to improve indoor air quality.
“With the U.S. economic stimulus having a great deal of focus on weatherization and other residential retrofits, we developed this change to help improve indoor air quality for public health and safety,” according to Steven Emmerich, committee chair.

Addendum "e" to ANSI/ASHRAE Standard 62.2-2007, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings, allows alternative methods for meeting the standard’s requirements regarding kitchen and bathroom exhaust fans. The standard currently requires fans in those rooms.

Addendum "e" can be found at ashrae.org/62.2e.

“For new construction or renovation, it’s simple to meet those requirements,” Max Sherman, former committee chair who now serves as consultant to the committee, says. “But the committee recognizes that installation of fans can be a barrier when added to existing homes in terms of expense and practicability. For example, an interior bathroom with ceiling joists running the wrong way may require ripping out a lot of ceiling and cutting studs to install ducting.”

An example of an alternative compliance path that is allowed under the addendum would be increasing the overall whole-house ventilation rate to compensate for insufficient or non-existent bathroom exhaust.

While the alternative path could result in modest increased energy use due to the extra whole-house ventilation required, Emmerich notes that the proposal is being made because experience has shown that people doing retrofits will often ignore the standard if the fan requirements are too onerous.

“This can lead to poor indoor air quality,” he noted.  “So while the preferred method is to have the right size exhaust fan, we are proposing this alternative,”Emmerich says.