Meet the requirements for both ventilation and monitoring.
Mechanically ventilated spaces
Option 1. ASHRAE Standard 62.1–2010
For mechanically ventilated spaces (and for mixed-mode systems when the mechanical ventilation is activated), determine the minimum outdoor air intake flow for mechanical ventilation systems using the ventilation rate procedure from ASHRAE 62.1–2010 or a local equivalent, whichever is more stringent.
Meet the minimum requirements of ASHRAE Standard 62.1–2010, Sections 4–7, Ventilation for Acceptable Indoor Air Quality (with errata), or a local equivalent, whichever is more stringent.
Option 2. CEN Standards EN 15251–2007 and EN 13779–2007
Projects outside the U.S. may instead meet the minimum outdoor air requirements of Annex B of Comité Européen de Normalisation (CEN) Standard EN 15251–2007, Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics; and meet the requirements of CEN Standard EN 13779–2007, Ventilation for nonresidential buildings, Performance requirements for ventilation and room conditioning systems, excluding Section 7.3, Thermal environment; 7.6, Acoustic environment; A.16; and A.17.
Naturally ventilated spaces
For naturally ventilated spaces (and for mixed-mode systems when the mechanical ventilation is inactivated), determine the minimum outdoor air opening and space configuration requirements using the natural ventilation procedure from ASHRAE Standard 62.1–2010 or a local equivalent, whichever is more stringent. 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 of ASHRAE Standard 62.1–2010, Section 4, or a local equivalent, whichever is more stringent. [Europe ACP: Arbeitsstaettenrichtlinie ASR 5] [Latin America ACP: Engineered Natural Ventilation Systems]
The indoor air quality procedure defined in ASHRAE Standard 62.1–2010 may not be used to comply with this prerequisite.
Mechanically ventilated spaces
For mechanically ventilated spaces (and for mixed-mode systems when the mechanical ventilation is activated), monitor outdoor air intake flow as follows:
- For variable air volume systems, provide a direct outdoor airflow measurement device capable of measuring the minimum outdoor air intake flow. This device must measure the minimum outdoor air intake flow with an accuracy of +/–10% of the design minimum outdoor airflow rate, as defined by the ventilation requirements above. An alarm must indicate when the outdoor airflow value varies by 15% or more from the outdoor airflow setpoint.
- For constant-volume systems, balance outdoor airflow to the design minimum outdoor airflow rate defined by ASHRAE Standard 62.1–2010 (with errata), or higher. Install a current transducer on the supply fan, an airflow switch, or similar monitoring device.
Naturally ventilated spaces
For naturally ventilated spaces (and for mixed-mode systems when the mechanical ventilation is inactivated), 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.
- 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 62.1–2010, Appendix C.
In addition to the requirements above, if the project building contains residential units, each dwelling unit must meet all of the following requirements.
- Unvented combustion appliances (e.g., decorative logs) are not allowed.
- Carbon monoxide monitors must be installed on each floor of each unit.
- All indoor fireplaces and woodstoves must have solid glass enclosures or doors that seal when closed.
- Any indoor fireplaces and woodstoves that are not closed combustion or power-vented must pass a backdraft potential test to ensure that depressurization of the combustion appliance zone is less than 5 Pa.
- Space- and water-heating equipment that involves combustion must be designed and installed with closed combustion (i.e., sealed supply air and exhaust ducting) or with power-vented exhaust, or located in a detached utility building or open-air facility.
- For projects in high-risk areas for radon, EPA Radon Zone 1 (or local equivalent for project outside the U.S.), design and construct any dwelling unit on levels one through four above grade with radon-resistant construction techniques. Follow the techniques prescribed in EPA Building Radon Out; NFPA 5000, Chapter 49; International Residential Code, Appendix F; CABO, Appendix F; ASTM E1465; or a local equivalent, whichever is most stringent [Canada ACP].
Alternative Compliance Paths (ACPs)
Canada ACP - Radon
Cities in Canada that have been proven to have an average radon concentration of 4 pCi/L (150 Bq/m3) or less through testing in accordance with the Health Canada Guide for Radon Measurements in Dwellings (with a minimum of 50 tests) are considered equivalent to EPA Radon Zone 2, and therefore are exempted from the radon requirements of this prerequisite.
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
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:
0,35 m² / person
1,05 m² / 10 m² room area
0,2 m² / person
0,6 m² / 10 m² room area
- 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).