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The results of the outdoor air quality investigation contribute to the overall assessment of air quality performance for the building and assist in identifying opportunities for providing or maintaining cleaner indoor air.

Spaces with Mechanical Ventilation (Excluding residential]

CALCULATE MINIMUM OUTDOOR AIR

ASHRAE Standard 62.1-2022 is the referenced ventilation standard for most commercial buildings. The Standard establishes minimum ventilation requirements and other measures for indoor air quality that is acceptable to human occupants and that minimizes adverse health effects. [95] This standard was adapted over recent years to include options for existing buildings to easily calculate the minimum outdoor air requirements. This provides new flexible approaches for buildings to achieve the minimum ventilation standards.

For all spaces with mechanical ventilation, calculate the minimum outdoor air required per ASHRAE Standard 62.1-2022, [96] using either the simplified calculations or the ventilation rate procedure:

• Simplified calculations . See ASHRAE 62.1-2022, Informative Appendix G. If the project’s ventilation system serves occupancy types not listed in Table G-1 of Informative Appendix G, [97] use the VRP to calculate the minimum outdoor air.

• Ventilation rate procedure (VRP) . See ASHRAE 62.1-2022, Section 6.2, [98] which uses outdoor air intake rates based on the space type and application, occupancy level, and floor area.

MEASURE OUTDOOR AIRFLOW

Measure the amount of outdoor air delivered by each ventilation system on the project. Conduct measurements to verify the amount of outdoor air delivered by each ventilation system. Perform measurements when the system is operating at the minimum outdoor airflow settings. Take outdoor airflow measurements at a location prior to mixing with any return air to ensure only the outdoor air flow rate is measured.

Facility managers or a third-party vendor can take measurements manually, or by flow measurement devices in the system. Flow measurement devices can degrade or deviate from the specified ranges over time, leading to inaccurate measurements. Prior to using

95 “ASHRAE 62.1-2022: Ventilation and Acceptable Indoor Air Quality”, ASHRAE. 96 “ASHRAE 62.1-2022: Ventilation and Acceptable Indoor Air Quality”, ASHRAE. 97 “ASHRAE 62.1-2022: Ventilation and Acceptable Indoor Air Quality”, ASHRAE. 98 “ASHRAE 62.1-2022: Ventilation and Acceptable Indoor Air Quality”, ASHRAE.

U.S. Green Building Council LEED v5 Reference Guide for Operations and Maintenance, April 2025 Launch Edition 210