To contribute to the comfort and well-being of building occupants by establishing minimum standards for indoor air quality (IAQ).
Mechanically Ventilated Spaces
For mechanically ventilated spaces (and for mixed-mode systems when the mechanical ventilation is activated), meet the requirements for both ventilation (option 1 or option 2) and monitoring.
Option 1. ASHRAE Standard 62.1–2016
Meet the requirements of ASHRAE Standard 62.1–2016, Sections 4, 5, 6.2, 6.5, and 7, or a local equivalent, whichever is more stringent.
Option 2. ISO 17772-1:2017 and EN 16798-3: 2017
Projects outside the U.S. may instead meet the requirements of ISO Standard 17772-1:2017, Section 6.3, using Method 1—Perceived air quality with Category I or II and local standard for ventilation system design such as EN Standard 16798-3: 2017, Sections 7-10.
Monitoring for mechanical ventilation systems
Provide outdoor air monitors for all mechanical ventilation systems with outdoor air intake flow greater than 1000 cfm (472 L/s). The monitoring device must be capable of measuring the minimum outdoor air intake flow and be capable of measuring the design minimum outdoor air intake flow with an accuracy of +/–10%. An alarm must indicate when the outdoor airflow value varies by 15% or more from the setpoint.
Alternatively, for constant-volume systems that do not employ demand control ventilation, provide an indicator capable of confirming the intake damper is open to the position needed to maintain the design minimum outdoor airflow as determined during the system startup and balancing.
Naturally Ventilated Spaces
For naturally ventilated spaces (and for mixed-mode systems when the mechanical ventilation is inactivated), confirm that natural ventilation is an effective strategy for the project by following the flow diagram in the Chartered Institution of Building Services Engineers (CIBSE) Applications Manual AM10, March 2005, Natural Ventilation in Nondomestic Buildings, Figure 2.8 and meet the requirements for both ventilation (option 1, option 2, or option 3) and monitoring.
Option 1. ASHRAE Standard 62.1-2016
Meet the requirements of ASHRAE 62.1-2016, Sections 4, 6.4, and 6.5.
Option 2. Engineered natural ventilation system
Meet the requirements of ASHRAE 62.1-2016, Sections 4 and 6.5, and have an engineered natural ventilation system approved by the authority having jurisdiction (per exception 1 of ASHRAE 62.1-2016 section 6.4).
Option 3. Historic building
This option is available to projects located in a building registered as a local or national historic building.
Meet the requirements of ASHRAE 62.1-2016, Sections 4, 6.4.1, 6.4.2, 6.4.3, and 6.5.
Monitoring for natural ventilation systems
Comply with at least one of the following strategies.
- Provide a direct exhaust airflow measurement device capable of measuring the exhaust airflow. This device must measure the exhaust airflow with an accuracy of +/–10% of the design minimum exhaust airflow rate. An alarm must indicate when airflow values vary by 15% or more from the exhaust airflow setpoint. This strategy is not allowed for projects using Natural Ventilation Option 3. Historic building.
- Provide automatic indication devices on all natural ventilation openings intended to meet the minimum opening requirements. An alarm must indicate when any one of the openings is closed during occupied hours.
- Monitor carbon dioxide (CO2) concentrations within each thermal zone. CO2 monitors must be between 3 and 6 feet (900 and 1 800 millimeters) above the floor and within the thermal zone. CO2 monitors must have an audible or visual indicator or alert the building automation system if the sensed CO2 concentration exceeds the setpoint by more than 10%. Calculate appropriate CO2 setpoints using the methods in ASHRAE 62.1–2016, Appendix D.
The indoor air quality procedure defined in ASHRAE Standard 62.1–2016, Section 6.3 may not be used to comply with this prerequisite.
Mechanical ventilation systems installed during core and shell construction must be capable of meeting projected ventilation levels and monitoring based on the requirements of anticipated future tenants.
In addition to the requirements above, if the project building contains residential units, each dwelling unit must meet the requirements of LEED v4.1 Multifamily EQ Prerequisite Minimum indoor air quality performance, EQ Prerequisite Combustion venting and EQ Prerequisite Radon-resistant construction.
Europe ACP: Naturally Ventilated Spaces
Projects in Europe may use the following approach:
- Design the spaces for natural ventilation. Consider typical site-specific local weather conditions, site location and terrain, outdoor environmental impacts (noise, car or industrial emissions, etc.), and the comfort and well-being of the occupants.
- Perform a design study for the building owner and building users comparing the advantages and disadvantages of the natural ventilation concept with a mechanical ventilation concept.
- Comply with the following minimum ventilation areas per person:
Table 1. Minimum ventilation area per person
0,35 m² / person
1,05 m² / person
0,2 m² / person
0,6 m² / person
The provided areas are the sum of supply an exhaust areas for an applicable room depth up to 10m. For the calculations use the number of people in the ventilation zone during use. To calculate ventilation area, if the window is covered with louvers, insect screens, or otherwise obstructed, the openable area must be based on the free unobstructed area through the opening.
Additionally, comply with the monitoring requirements outlined in the credit.
Submittal Documentation for Europe ACP:
Provide a narrative demonstrating the natural ventilation concept can contribute to the comfort and well-being of the occupants. Include the following information:
- Design studies which compare the natural ventilation concept with a mechanical ventilation concept along with a description of the advantages and disadvantages for the building owner and building user.
- Description of the principal natural ventilation concept (single-sided or cross-ventilation). If the design proposes a mix of the two, provide plans and/or sections with highlighted areas for each of the natural ventilation modes.
- Description of the proposed façade openings (type of windows, louvers, etc.) and their opening mechanisms
Latin America ACP: Engineered Natural Ventilation Systems
Projects in Latin America may follow the Verification Protocol for Engineered Natural Ventilation Systems in Equatorial Climates and receive a design review and approval from the Colombian Professional Association of Air-conditioning, Ventilation and Refrigeration (ACAIRE).
© Copyright U.S. Green Building Council, Inc. All rights reserved.
Please sign in to leave a comment.