The American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE) published its Standard 62.2, "Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings," in 2003, issued a revised version in 2007, and released the current version in 2010. The 2013 edition should be out soon.
ASHRAE 62.2 is referenced in state building codes, and it's used by manufacturers to size their equipment and ductwork. It's the subject of a comprehensive training package offered by the Federal Government's Weatherization Assistance Program Technical Assistance Center. But is it right? Maybe … and maybe not, says building scientist Joseph Lstiburek.
In an interview with energy rater Allison Bailes published on Bailes' "Energy Vanguard" blog ("Interview with Dr. Joe Lstiburek — The Ventilation Debate Continues") Lstiburek said a little more than that, in fact. Bailes sums up Lstiburek's attack on ASHRAE 62.2 like this: "He contends that the residential ventilation standard, ASHRAE 62.2, ventilates at too high a rate, causing problems with humidity in hot or mixed humid climates, comfort and dryness in cold climates, and too much energy use everywhere. The 2013 version makes it worse."
Talking with Bailes, Lstiburek said that the ventilation rates called for in ASHRAE 62.2 are excessive: "We know that houses ventilated at the 62.2 rate lead to comfort problems in cold climates by drying out the building and drying out furnishings. We know that ventilating at the 62.2 rates in houses built to the Model Energy Code lead to part-load humidity problems. We know for a fact that these rates lead to humidity problems in the South and dryness and comfort issues in the North, so that's not a guess. We know this from experience."
And Lstiburek says homes have historically performed well at lower air change rates: "We also know that millions of houses were constructed in the 1990s and 2000s that were between 3 and 5 air changes per hour at 50 Pascals with no ventilation systems and their air change rates are between 0.2 and 0.3 air changes per hour as tested by tracer gas work and that's consistent with houses tested in the '70s and '80s as well. The myth of the old leaky house is just a myth. These houses had no ventilation systems in them at all and they're not suffering from indoor air quality problems because nobody's measured any contaminants. There's no measurements."