ASHRAE+62.1-2022+(1) - Page 031
Extracted Content
6.4.4 Documentation. Where the Natural Ventilation Procedure is used, the designer shall document the values and calculations that demonstrate conformance with the compliance path and the controls systems and sequences required for operation of the natural ventilation system, including coordination with mechanical ventilation systems. Where the Prescriptive Compliance Path is used for buildings located in an area where the national standard for one or more contaminants is exceeded, any design assumptions and calculations related to the impact on IAQ shall be included in the design documents.
6.5 Exhaust Ventilation. The Prescriptive Compliance Path or the Performance Compliance Path shall be used to meet the requirements of this section. Exhaust makeup air shall be permitted to be any combination of outdoor air, recirculated air, or transfer air.
6.5.1 Prescriptive Compliance Path. The design exhaust airflow shall be determined in accordance with the requirements in Tables 6-2 and 6-3.
Exception to 6.5.1: Laboratory spaces that comply with all requirements of ANSI/AIHA Z9.5.
6.5.1.1 Laboratory Hoods. Exhaust from laboratory hoods shall be Air Class 4 unless determined otherwise by the EHS professional responsible to the owner or to the owner’s designee.
6.5.1.2 Pressure Requirements. While the required exhaust systems are operating, the exhaust airflow of zones listed in Table 6-2 shall be larger than their respective supply airflow. If zones listed in Table 6-2 are adjacent, the difference between the exhaust and the supply airflow shall be larger for the zone with the higher number class of air.
Exception to 6.5.1.2: Where airflow offset requirements are established by the EHS professional
responsible to the owner or owner’s designee.
Informative Notes:
- Exhaust systems are required for any occupancy category listed in Table 6-2.
- Where intermittent operation is allowed in Table 6-2, exhaust equipment is intended to be operated when the space is in use.
6.5.2 Performance Compliance Path. The exhaust airflow shall be determined in accordance with the following subsections.
6.5.2.1 Contaminant Sources. Contaminants or mixtures of concern for purposes of the design shall be identified. For each contaminant or mixture of concern, indoor sources (occupants, materials, activities, and processes) and outdoor sources shall be identified, and the emission rate for each contaminant of concern from each source shall be determined.
6.5.2.2 Contaminant Concentration. For each contaminant of concern, a concentration limit and its corresponding exposure period and an appropriate reference to a cognizant authority shall be specified.
6.5.2.3 Monitoring and control systems shall be provided to automatically detect contaminant levels of concern and modulate exhaust airflow such that contaminant levels are maintained at not greater than the specified contaminant concentration limits.
6.6 Design Documentation Procedures. Design criteria and assumptions shall be documented and made available for operation of the system after installation. See Sections 4.3, 5.10.3, 5.13.4, 6.2.6.1.5, 6.3.5, and 6.4.4 regarding assumptions to be detailed in the documentation.
7. CONSTRUCTION AND SYSTEM START-UP
Compliance with Sections 7.1 and 7.2 is required for all buildings. Section 7.3 is required for buildings designed under the Indoor Air Quality Procedure in Section 6.3.
7.1 Construction Phase 7.1.1 Application. The requirements of this section apply to ventilation systems and the spaces they serve in new buildings and additions to or alterations in existing buildings.
7.1.2 Filters. Systems designed with particle filters shall not be operated without filters in place. 7.1.3 Protection of Materials. When recommended by the manufacturer, building materials shall be protected from rain and other sources of moisture by appropriate in-transit and on-site procedures. Porous materials with visible microbial growth shall not be installed. Nonporous materials with visible microbial growth shall be decontaminated.
7.1.4 Protection of Occupied Areas 7.1.4.1 Application. The requirements of Section 7.1.4 apply when construction requires a building permit and entails sanding, cutting, grinding, or other activities that generate significant amounts of airborne particles or procedures that generate significant amounts of gaseous contaminants.
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