ASHRAE updates air quality standard

When installing a high-efficiency furnace, if there is a gas water heater some consideration must be given on how to vent it. (Photos courtesy of ClimateCare)
Changes have been made to ANSI/ASHRAE Standard 62.1-2019, Ventilation for Acceptable Indoor Air Quality (IAQ), which specifies the minimum ventilation rates as of November 2019. Other measures are also included for new and existing buildings that are intended to provide IAQ that is acceptable to occupants and that minimizes adverse health effects.
Key changes include new informative tables of ventilation rates per unit area for checking new and existing building ventilation calculations, a simplified version of the ventilation rate procedure – improving calculations for system ventilation efficiency and zone air distribution effectiveness, a modified natural ventilation procedure calculation methodology, revised score to specifically identify occupancies previously not covered, a new requirement that natural ventilation consider the quality of the outdoor air and interaction of the outdoor air with mechanically cooled spaces, and humidity control requirement now expressed as dew point instead of relative humidity.
The standard defines roles and the minimum requirements for mechanical and natural ventilation systems and the building envelope intended to provide acceptable indoor air quality in residential buildings.
The 2019 edition adds a compliance path that gives credit for particle filtration. This determines the difference between balanced and unbalanced ventilation system interactions with natural infiltration. New multi-family dwellings will now require compartmentalization limits and single-point envelope leakage test results can be used when calculating infiltration credit.
“These standards have undergone key changes over the years, reflecting the ever-expanding body of knowledge, experience and research related to ventilation and air quality,” said Jennifer Isenbeck, chair of the Standing Standard Project Committee for Standard 62.1.
Versions of all ASHRAE standards are available online for free as read-only or for purchase at www.ashrae.org.