Data were collected to characterize whole-house mechanical ventilation (WHMV) and indoor
air quality (IAQ) in 139 homes across four US regions, including 29 in the Marine climate of
Oregon, 26 in Cold-Dry Colorado, 32 in Mixed-Humid Illinois, and 52 in the Hot-Humid
Southeast. Thirty-six homes were monitored with and without WHMV operating. All homes
had operational cooktop ventilation and bathroom exhaust. Envelope and duct airtightness;
mechanical ventilation airflows; time-resolved CO2, PM2.5 formaldehyde and radon; and time-
integrated NO2, NOx and formaldehyde were measured. Participants provided information
about IAQ-impacting activities, perceptions and ventilation use. Preliminary results indicate
that the installed WHMV often did not meet requirements of ASHRAE 62.2-2010; WHMV
was operating in only half of the homes as found and 22% had WHMV airflow at or above the
requirement, as found. Homes with WHMV had significantly lower CO2 and radon
concentrations compared to those without WHMV running