ASHRAE+62.1-2022+(1) - Page 018
Extracted Content
6.1.4.1 Particulate Matter Smaller than 10 Micrometers (PM10). In buildings located in an area where the national standard or guideline for PM10 is exceeded, particle filters or air-cleaning devices shall be provided to clean the outdoor air at any location prior to its introduction to occupied spaces. Particulate matter filters or air cleaners shall have either
a. a MERV of not less than 8 where rated in accordance with ASHRAE Standard 52.2 or b. the minimum efficiency within ISO ePM10 where rated in accordance with ISO 16890.
Informative Note: See Informative Appendix E for resources regarding selected PM10 national standards and guidelines.
6.1.4.2 Particulate Matter Smaller than 2.5 Micrometers (PM2.5). In buildings located in an area where the national standard or guideline for PM2.5 is exceeded, particle filters or air-cleaning devices shall be provided to clean the outdoor air at any location prior to its introduction to occupied spaces. Particulate matter filters or air cleaners shall have either
a. a MERV of not less than 11 where rated in accordance with ASHRAE Standard 52.2 or b. the minimum efficiency within ISO ePM2.5 where rated in accordance with ISO 16890.
Informative Note: See Informative Appendix E for resources regarding selected PM2.5 national standards and guidelines.
6.1.4.3 Ozone. Air-cleaning devices for ozone shall be provided when the most recent three-year average annual fourth-highest daily maximum eight-hour average ozone concentration exceeds 0.100 ppm (195 μg/m [3] ).
Such air-cleaning devices shall have a volumetric ozone removal efficiency of not less than 40% where installed, operated, and maintained in accordance with the manufacturer’s recommendations and shall be approved by the AHJ. Such devices shall be operated where the outdoor ozone levels are expected to exceed 0.100 ppm (195 μg/m [3] ). Exceptions to 6.1.4.3: Air cleaning for ozone shall not be required where
- the system design outdoor air intake flow is 1.5 ach or less,
- controls are provided that sense outdoor ozone level and reduce intake airflow to 1.5 ach or less while complying with the outdoor airflow requirements of Section 6, or
- outdoor air is brought into the building and heated by direct-fired makeup air units. Informative Note: In the U.S., a most recent three-year average annual fourth-highest daily maximum eight-hour average ozone concentration exceeding 0.100 ppm (195 μg/m [3] ) equates to a U.S. EPA eight-hour ozone classification of “Serious” or higher (Severe 15, Severe 17, or Extreme).
6.1.4.4 Other Outdoor Contaminants. In buildings located in an area where the national standard for one or more contaminants not addressed in Section 6.1.4 is exceeded, any design assumptions and calculations related to the impact on IAQ shall be included in the design documents.
6.2 Ventilation Rate Procedure. The outdoor air intake flow ( Vot ) for a ventilation system shall be determined in accordance with Section 6.1.4 and Sections 6.2.1 through 6.2.6.
Informative Note: Additional explanation of terms used below is contained in Normative Appendix A, along with a ventilation system schematic (Figure A-1).
6.2.1 Zone Calculations. Ventilation zone parameters shall be determined in accordance with Sections 6.2.1.1 through Section 6.2.1.3 for ventilation zones served by the ventilation system, except that the ventilation rates from ASHRAE/ASHE Standard 170 shall be used for the occupancy categories within the scope of ASHRAE/ASHE Standard 170. For outpatient facilities outside the scope of ASHRAE/ASHE Standard 170, refer to Normative Appendix D. Informative Note: The ventilation rates in ASHRAE/ASHE Standard 170 are intended to achieve asepsis and control odor migration and might not be adequate to achieve acceptable IAQ as defined in Standard 62.1.
6.2.1.1 Breathing Zone Outdoor Airflow. The outdoor airflow required in the breathing zone ( Vbz ) of the occupiable space or spaces in a ventilation zone shall be not less than the value determined in accordance with Equation 6-1.
Vbz = Rp × Pz + Ra × Az (6-1)
where
Az = zone floor area, the net occupiable floor area of the ventilation zone, ft [2 ] (m [2] )
Pz = zone population, the number of people in the ventilation zone during use
16 ANSI/ASHRAE Standard 62.1-2022