ASHRAE Updates Standards for Ventilation, Air Quality

ASHRAE released updated editions of its standards for ventilation system design and acceptable indoor air quality (IAQ). ANSI/ASHRAE Standard 62.1-2019, Ventilation for Acceptable Indoor Air Quality, specifies minimum ventilation rates and other measures for new and existing buildings to foster IAQ that is acceptable to human occupants and that minimizes adverse health effects.

Significant changes include:

· New tables of ventilation rates per unit area for checking new and existing building ventilation calculations
· Simplified version of the Ventilation Rate Procedure
· Modified Natural Ventilation Procedure calculation methodology
· Revised scope to specifically identify occupancies previously not covered
· New requirement that natural ventilation consider the quality of the outdoor air and interaction of the outdoor air with mechanically cooled spaces
· Humidity control requirements now expressed as dew point instead of relative humidity

The 2019 edition of Standard 62.2 adds a compliance path that gives credit for particle filtration, distinguishing between balanced and unbalanced ventilation system interactions with natural infiltration. The standard also requires compartmentalization limits for new multifamily dwellings, and allows for single-point envelope leakage test results to be used when calculating infiltration credit.

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