ASHRAE 62.2 specifies a minimum of 0.35 airchanges per hour for residences built in 2008 or later. Your certainty about the situation, however, is noted.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.