Ventilation and Indoor Air Quality in New Homes

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Tamara R Pearlman

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Dec 22, 2009, 3:21:33 PM12/22/09

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Concerns have been raised regarding whether homeowners use windows,
exhaust fans, and other mechanical ventilation devices enough to
remove indoor air contaminants and excess moisture. In a multi season
study of ventilation and indoor air quality of 108 new single family,
detached homes in California, window use, ventilation rates, and air
contaminant concentrations were measured. The median 24 hour outdoor
air exchange rate was 0.26 air changes per hour; 67 percent of the
homes were below the California building code requirement of 0.35 air
changes per hour; and 32 percent of the homes did not use their
windows. Home to garage pressure testing guidelines were exceeded in
65 percent of the homes.

The median indoor formaldehyde concentration was 36 micrograms per
cubic meter (range of 4.8 to 136 micrograms per cubic meter). Nearly
all homes had formaldehyde concentrations that exceeded guidelines for
cancer and chronic irritation, while 59 percent exceeded guidelines
for acute irritation. In conclusion, new single family detached homes
in California are built relatively airtight, can have very low outdoor
air exchange rates, and can often exceed exposure guidelines for air
contaminants with indoor sources, such as formaldehyde and some other
volatile organic compounds. Mechanical ventilation systems are needed
to provide a dependable, continuous supply of outdoor air to new
homes, and reductions of various indoor formaldehyde sources are also
needed.