What is ASHRAE?
ASHRAE stands for the American Society of Heating, Refrigerating and Air-Conditioning Engineers, which is the technical body that develops and maintains ventilation standards for the United States. Ventilation codes and energy efficiency programs throughout the U.S. are based on ASHRAE standards.
What is ASHRAE Standard 62.2?
Formed in 1996, the ASHRAE 62.2 committee developed and maintains a residential ventilation standard for buildings three stories and less which is titled Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings. It is reviewed and revised every three years. The first version of Standard 62.2 was published in 2003, the second in 2007, and the most current version is ANSI/ASHRAE Standard 62.2-2010. (ANSI stands for the American National Standards Institute. ANSI certification of a standard means that a specific consensus process was used to develop and maintain the standard and is required for adoption of a standard into codes.) The 2013 edition will become available in the summer of 2013.
ASHRAE Standard 62.2 is the ventilation standard that applies to low-rise residential buildings of three stories or less in the U.S. ASHRAE Standard 62.1 applies to all other buildings.
ASHRAE Standard 62.2-2007 is the 2007 edition of the ASHRAE document entitled Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings. ASHRAE Standard 62.2-2007 is the basis for the ventilation code in California. Title 24 Part 6 (2008) requires compliance with ASHRAE 62.2-2007 when alterations are made in an existing home or when a project includes an addition of 1,000 sq ft or greater. Additions of 1,000 sq ft or less are exempted from meeting Title 24 ventilation requirements.
ASHRAE Standard 62.2-2010
ASHRAE Standard 62.2-2010 is the 2010 edition of the ASHRAE document entitled Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings. For the purposes of this website, requirements of Standard 62.2-2010 include the published addenda to that edition through May 2012. which includes the addenda in the published 2011 Supplement and Addenda j and n. These addenda are available online for free from ASHRAE.
When ASHRAE Standard 62.2 is Not Enough
Is ASHRAE Standard 62.2 current best practice for ventilation? In a word, no. ASHRAE 62.2 is a standard that national experts could agree upon that sets a minimum standard for ventilation — not best practice, which would further customize ventilation rates based on factors such as number of occupants in a dwelling and strength of pollutant sources.
Meeting the ventilation requirements for ASHRAE Standard 62.2 will not always provide enough ventilation for a home. In these circumstances, ventilation rates need to be increased beyond the Standard.
- The Standard does not address high-polluting events such as painting, cleaning, smoking or construction projects.
- The Standard does not address the use of unvented combustion space heaters such as unvented decorative gas appliances and kerosene heaters, which are not allowed in California.
- The Standard assumes one person per bedroom, with two people in the master bedroom. Higher numbers of occupants will increase ventilation needs.
- Occupants with health issues such as asthma and allergies may benefit from increased ventilation and/or filtration.
How Have Ventilation Rates Changed Over Time?
Early ventilation interests in the U.S. focused on preventing the spread of airborne diseases, especially tuberculosis. By the late 1800s, proper ventilation in the U.S. was defined as 30 cfm/person, and by 1925 this ventilation rate was set by law in 22 states.
ASHRAE Standard 62-1973 required ventilation in most buildings of 20 cfm per person. In 1981, ASHRAE 62 reduced the rate to 5cfm per person in an effort to address the energy impact of ventilation. This was quickly found to be far too low a ventilation rate. ASHRAE 62 was updated in 1989 and set a residential ventilation rate of 15 cfm per person or 0.35 ACH, whichever was higher. However, this version of the Standard contained only a half-page on residential ventilation. In the early 1990s, ASHRAE began the process of updating Standard 62 and in 1997 separated the overall standard into two documents with two committees, SPC 62.1 that dealt with all the occupancies other than low-rise residential and SPC 62.2 that dealt with low-rise residential only.
The complete draft of Standard 62.2 was first sent out for public review in 1999 and included a requirement for continuous whole-building ventilation at a rate of 7.5 cfm per person, assuming 2 people in the master bedroom, plus 0.01 cfm per sq ft of occupiable area. This reduced the per-person rate found in 62-89 but added an allowance for the size of the house or apartment. Research had shown that the number of occupants had a higher impact on indoor air quality (IAQ) than the volume of the building. Smaller units got higher rates while larger units got lower rates when compared to ASHRAE 62-1989. After three public reviews, the new residential IAQ standard was first published as an ASHRAE standard in 2003 and updated in 2004 as an ANSI/ASHRAE standard. It was placed in Continuous Maintenance status as a High Profile standard by the ASHRAE Board, meaning that the committee was directed to consider proposed changes continuously and update the standard and then to republish it every three years. Therefore, it was updated in 2007 and again in 2010. It will be published again in 2013 with the updates since 2010.