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This project committee is responsible for maintaining ASHRAE Standard 62.2,
Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings

Standard 62.2-2007 -- Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings (ANSI/ASHRAE Approved)

Because of the effects it has on health, comfort, and serviceability, indoor air quality in our homes is becoming an increasing concern to many people. According to the American Lung Association, pollutants within our homes have been increasingly recognized as threats to our respiratory health. The Environmental Protection Agency lists poor indoor air quality as the fourth-largest environmental threat to our country. Asthma is the leading serious chronic illness of children in the United States. Moisture-related construction defects and damage are on the increase in new houses. Minimum residential ventilation can improve many of these indoor air quality problems.

ASHRAE has long been in the business of ventilation, but most of the focus of that effort has been in the area of commercial and institutional buildings. Residential ventilation was traditionally not a major concern because it was felt that between operable windows and envelope leakage, people were getting enough air. In the 30 years since the first oil shock, houses have become much more energy efficient. At the same time, the kinds of materials used and functions present in houses were changing in response to people’s needs. People were also becoming more environmentally conscious, not only about the resources they were consuming but also about the environment in which they lived. All of these factors contributed to an increasing level of public concern about residential indoor air quality and ventilation. Where once there was an easy feeling about the residential indoor environment, there is now a desire to define levels of acceptability and performance. Many institutions—both public and private—have interests in indoor air quality (IAQ), but ASHRAE, as the professional society that has had ventilation as part of its mission for over 100 years, was the logical place to develop a consensus standard.

In developing this standard the committee recognized that there were many different kinds of houses, many different climates, and many different styles of construction. To accommodate these differences, the major requirements were designed with several alternate paths to allow users flexibility. Some requirements are performance based, with specific prescriptive alternatives. The standard recognizes that there are several different ways to achieve a specified ventilation rate and allows both mechanical and natural methods.

There are three primary sets of requirements in the standard and a host of secondary ones. The three primary sets involve whole-house ventilation, local exhaust, and source control. Whole-house ventilation is intended to dilute the unavoidable contaminant emissions from people, from materials, and from background processes. Local exhaust is intended to remove contaminants from those specific rooms (e.g., kitchens and bathrooms) in which sources are expected because of their design function. Other source control measures are included to deal with those sources that can reasonably be anticipated to be found in a residence.

The standard’s secondary requirements focus on properties of specific items that are needed to achieve the main objectives of the standard. Examples of this include sound and flow ratings for fans and labeling requirements. Some of the secondary requirements as well as the guidance in the appendices help keep the design of the building as a system from failing because ventilation systems were installed. For example, ventilation systems that depressurize the house can cause natural draft combustion appliances to backdraft or draw in pollutants (including moisture) through leaks. The standard may seem to be principally about ventilation, but the purpose of ventilation is to provide acceptable IAQ. As indicated in ASHRAE’s position document on indoor air quality, the most effective strategy for keeping exposure to undesirable pollutants low is usually to keep them from being released to the general indoor environment in the first place. Such “source control” measures actually make up the bulk of the pages in this standard, since local ventilation is intended to exhaust pollutants from specific rooms before they spread throughout the house. Whole-house ventilation is intended to bring fresh air into the general environment to dilute the pollutants that cannot be effectively controlled at the source.

The standard does not address specific pollutant concentration levels. It does not address certain potential pollutant sources such as unvented combustion space heaters and contaminant migration from polluted buffer zones (such as garages, etc.). It also does not address contamination from outdoor sources or from episodic occupant-controlled events such as painting, smoking, cleaning, or other high-polluting events. It does not include credit for air cleaning or for pollutant detection devices such as carbon monoxide alarms or volatile organic compound (VOC) controllers. While many of these considerations could be important factors in achieving acceptable IAQ, the committee believes that these issues are not yet ready for inclusion in a minimum standard. The committee continues to work on many of these issues for inclusion in either a companion guideline or as potential future addenda.

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ANSI/ASHRAE Standard 62.2 is under continuous maintenance by SSPC 62.2 for which the Standards Committee has established a documented program for regular publication of addenda or revisions.