ANSI/ASHRAE Standard 62.1-2019: Ventilation for Acceptable Indoor Air Quality
About this book
ASHRAE Standard 62.1, "Ventilation and Acceptable Indoor Air Quality in Buildings" (formerly "Ventilation for Acceptable Indoor Air Quality"), establishes minimum ventilation rates and other measures intended to provide indoor air quality that is acceptable to human occupants and that minimizes adverse health effects. It is the reference ventilation standard for all commercial and institutional buildings in the United States, referenced by most state and local building codes, and widely adopted internationally. The standard addresses two distinct strategies for achieving acceptable indoor air quality: the Ventilation Rate Procedure (VRP), which prescribes minimum outdoor air supply rates based on occupancy type and floor area; and the Indoor Air Quality Procedure (IAQP), which allows lower ventilation rates to be specified if enhanced filtration or source control measures can demonstrate equivalent air quality outcomes.
A major structural revision occurred in the 2010 edition, when the standard adopted the "multi-zone recirculating system" (MRSA) equation approach for specifying outdoor air quantities in systems serving multiple zones. This approach, sometimes called the "breathing zone outdoor airflow" method, accounts for the efficiency of air distribution and the zone-level composition of outdoor and recirculated air to determine the minimum outdoor air required at the air handling unit level. The 2019 and 2022 editions incorporated expanded guidance on filtration (referencing MERV ratings and now aligning with ASHRAE 241 for infection control), indoor air quality monitoring requirements, and updated ventilation rates reflecting current research on the relationship between ventilation, CO2 concentrations, and cognitive performance.
Research has consistently shown that ventilation rates above the minimum requirements correspond to measurable improvements in occupant productivity, health outcomes, and sick building syndrome symptom rates. For green building design, ASHRAE 62.1 forms the baseline ventilation requirement in LEED, BREEAM, and most other certification programs. The standard's requirements for kitchen exhaust, garage ventilation, laboratory fume hoods, and specific occupancy types make it a comprehensive reference for any mechanical engineer designing occupied buildings.
Sources: ASHRAE (ashrae.org); ASHRAE Standard 62.1-2022 official publication; ASHRAE Standard 62.1 User's Manual; Indoor Air Quality scientific literature.