Table 1. Minimum ventilation area
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Credit language
© Copyright U.S. Green Building Council, Inc. All rights reserved.
Requirements
Establishment
Mechanically ventilated spaces
For mechanically ventilated spaces (and for mixed-mode systems when the mechanical ventilation is activated), chose one of the following:Case 1. Systems able to meet required outdoor airflow rates
Option 1. ASHRAE Standard 62.1-2010
Modify or maintain each outdoor air intake, supply air fan, and ventilation distribution system to meet the outdoor air intake flow rates, using the ASHRAE ventilation rate procedure or a local equivalent, whichever is more stringent and 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. [India ACP: Mechanically Ventilated]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.Case 2. Systems unable to meet required outdoor airflow rates
If meeting the outdoor airflow rates in Case 1 is not feasible because of the physical constraints of the existing ventilation system, complete an engineering assessment of the system’s maximum outdoor air delivery rate. Supply the maximum possible to reach the minimum setpoint in Case 1 and not less than 10 cubic feet per minute (5 liters per second) of outdoor air per person.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. [Europe ACP: Arbeitsstaettenrichtlinie ASR 5], [India ACP: Naturally Ventilated NBC] 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], [India ACP: Naturally Ventilated CPCB]All spaces
The indoor air quality procedure defined in ASHRAE Standard 62.1–2010 may not be used to comply with this prerequisite.
Performance
Show compliance through measurements taken at the system level within five years of the end of the performance period. Implement and maintain an HVAC system maintenance program, based on ASHRAE 62.1–2010, Section 8, or a local equivalent, whichever is more stringent, to ensure the proper operations and maintenance of HVAC components as they relate to outdoor air introduction and exhaust.Alternative Compliance Paths (ACPs)
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
- 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
- For single-zone and 100% outside air systems, National Building Code of India 2005 (NBC 2005) Table 4-air rate requirements in lieu of ASHRAE 62.1-2010 ventilation rate procedure. Only certain space types are eligible.
- Central Pollution Control Board (CPCB), National Ambient Air Quality Standards in lieu of ASHRAE 62.1-2010, Section 4.
- NBC 2005 Part 8, section 3, clause 3.2, with additional parameters, in lieu of ASHRAE 62.1-2010, Minimum Requirements, Sections 5-7.
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Continuous ventilation |
Intermittent ventilation |
|---|---|---|
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Single-sided |
0,35 m² / person |
1,05 m² / 10 m² room area |
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Cross-ventilation |
0,2 m² / person |
0,6 m² / 10 m² room area |
India ACP: Mechanically Ventilated
Projects in India may meet the following as a local equivalent to ASHRAE 62.1-2010:India ACP: Naturally Ventilated NBC
Projects in India may use NBC 2005 Part 8, Section 1, clauses 5.2.1-5.6 and Appendix A: Design for Natural Ventilation from Handbook on Functional Requirements of Buildings (other than Industrial Buildings), also known as SP 41, 1987 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure.India ACP: Naturally Ventilated CPCB
Projects in India may compare outdoor air quality with the CPCB National Ambient Air Quality Standards in lieu of the U.S. national air quality standards as required in ASHRAE Standard 62.1-2010, Section 4.Pilot Alternative Compliance Path Available
This credit has a pilot ACP available in the LEED Pilot Credit Library. See Indoor air quality procedure - alternative compliance path for more informationWhat does it cost?
Cost estimates for this credit
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Our tab contains overall cost guidance, notes on what “soft costs” to expect, and a strategy-by-strategy breakdown of what to consider and what it might cost, in percentage premiums, actual costs, or both.
This information is also available in a full PDF download in The Cost of LEED v4 report.
Learn more about The Cost of LEED v4 »Frequently asked questions
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What happened to the IEQ Space Matrix that was available to version 2009 projects? What should I reference to determine how spaces in my building should be categorized for this prerequisite? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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How do I find whether my project is located in a non-attainment area for particulate matter or exceeds the prerequisite ozone requirements? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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The outdoor air intake for our ventilation system is not accessible, and it’s not possible to measure the outdoor airflow directly. How can we determine the outdoor airflow for this system? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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Our system cannot provide enough outdoor air to meet ASHRAE 62.1-2010 due to design limitations. How much outdoor air must we provide to meet Case 2 instead? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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My building has 80 AHUs providing ventilation to building spaces. Do I have to do the ventilation calculations and conduct outdoor air measurements for each one? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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What if after our Preliminary Review we have to revise the ventilation rate procedure calculations and find that we need to make corrections to the system in order to meet the prerequisite? Can we redo the outside air testing after making corrections? Would we need to update the performance period for all credits accordingly? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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What if our systems do not meet the required outside air when systems are tested at worst-case conditions? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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Our building has a single fan that supplies outside air to multiple AHUs. Do we need to perform outside air testing at the supply fan or at all AHUs? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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We have a VAV system where single AHUs serve multiple zones. Do we need to take outside air measurements at each VAV box? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
Addenda
4/6/2018 – Updated: 11/6/2020
Regional ACP
Description of change:
Campus Applicable
No
Internationally Applicable:
No
7/8/2017 – Updated: 11/6/2020
Regional ACP
Description of change:
Revise the Europe ACP to the following:
"Projects in Europe may use Arbeitsstaettenrichtlinie ASR 5 or ASR A3.6 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure."
"Projects in Europe may use Arbeitsstaettenrichtlinie ASR 5 or ASR A3.6 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure."
Campus Applicable
No
Internationally Applicable:
No
4/6/2018 – Updated: 11/6/2020
Reference Guide Correction
Description of change:
Table 1. Minimum ventilation area
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Campus Applicable
No
Internationally Applicable:
No
4/1/2015 – Updated: 3/29/2018
Regional ACP
Description of change:
After the first paragraph add the following:
Projects in India may meet the following as a local equivalent to ASHRAE 62.1-2010:
- For single-zone and 100% outside air systems, National Building Code of India 2005 (NBC 2005) Table 4-air rate requirements in lieu of ASHRAE 62.1-2010 ventilation rate procedure. Only certain space types are eligible.
- Central Pollution Control Board (CPCB), National Ambient Air Quality Standards in lieu of ASHRAE 62.1-2010, Section 4.
- NBC 2005 Part 8, section 3, clause 3.2, with additional parameters, in lieu of ASHRAE 62.1-2010, Minimum Requirements, Sections 5-7.
Projects in India may meet the following as a local equivalent to ASHRAE 62.1-2010:
- For single-zone and 100% outside air systems, National Building Code of India 2005 (NBC 2005) Table 4-air rate requirements in lieu of ASHRAE 62.1-2010 ventilation rate procedure. Only certain space types are eligible.
- Central Pollution Control Board (CPCB), National Ambient Air Quality Standards in lieu of ASHRAE 62.1-2010, Section 4.
- NBC 2005 Part 8, section 3, clause 3.2, with additional parameters, in lieu of ASHRAE 62.1-2010, Minimum Requirements, Sections 5-7.
Campus Applicable
No
Internationally Applicable:
Yes
4/1/2015 – Updated: 3/29/2018
Regional ACP
Description of change:
After the first paragraph add the following:
"Projects in India may use NBC 2005 Part 8, Section 1, clauses 5.2.1-5.6 and Appendix A: Design for Natural Ventilation from Handbook on Functional Requirements of Buildings (other than Industrial Buildings), also known as SP 41, 1987 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure."
After the second paragraph add the following:
"Projects in India may compare outdoor air quality with the CPCB National Ambient Air Quality Standards in lieu of the U.S. national air quality standards as required in ASHRAE Standard 62.1-2010, Section 4."
"Projects in India may use NBC 2005 Part 8, Section 1, clauses 5.2.1-5.6 and Appendix A: Design for Natural Ventilation from Handbook on Functional Requirements of Buildings (other than Industrial Buildings), also known as SP 41, 1987 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure."
After the second paragraph add the following:
"Projects in India may compare outdoor air quality with the CPCB National Ambient Air Quality Standards in lieu of the U.S. national air quality standards as required in ASHRAE Standard 62.1-2010, Section 4."
Campus Applicable
No
Internationally Applicable:
Yes
7/1/2016 – Updated: 7/15/2016
Reference Guide Correction
Description of change:
Revise the bullet "BAS data for minimum outdoor air setpoints" to "Minimum outdoor air setpoints"
Campus Applicable
No
Internationally Applicable:
No
6/3/2016 – Updated: 6/3/2016
Form Update
Description of change:
1. Fixed bug with default values for zone population in the single zone sheet
2. Updated Table 6-3 calculation for Ev in the multiple zone sheet to not exceed 1.0 when Max Zp3. In multiple zone sheet, changed Ep from user entry to calculated value.
4. Added column for Zone outdoor airflow provided to the 100% OA and corresponding column in the summary tab (zone outdoor airflow provided meets or exceeds Voz for all zones).
5. Note added to Are you using default value for zone population to clarify default values should only be used if expected occupancy is unknown.
6. Modified rounding and decimals displayed
7. Fixed bug in summary sheet so that all systems are always displayed.
2. Updated Table 6-3 calculation for Ev in the multiple zone sheet to not exceed 1.0 when Max Zp3. In multiple zone sheet, changed Ep from user entry to calculated value.
4. Added column for Zone outdoor airflow provided to the 100% OA and corresponding column in the summary tab (zone outdoor airflow provided meets or exceeds Voz for all zones).
5. Note added to Are you using default value for zone population to clarify default values should only be used if expected occupancy is unknown.
6. Modified rounding and decimals displayed
7. Fixed bug in summary sheet so that all systems are always displayed.
Campus Applicable
No
Internationally Applicable:
No
4/1/2015 – Updated: 4/7/2016
Regional ACP
Description of change:
Add the following after the text for Naturally Ventilated Spaces:
"Projects in Europe may use Arbeitsstaettenrichtlinie ASR 5 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure."
"Projects in Europe may use Arbeitsstaettenrichtlinie ASR 5 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure."
Campus Applicable
No
Internationally Applicable:
Yes
4/1/2015 – Updated: 4/16/2015
Form Update
Description of change:
Revised form to include India ACP for mechanically ventilated space (Case 1) and naturally ventilated spaces.
Campus Applicable
No
Internationally Applicable:
Yes
4/1/2015 – Updated: 4/1/2015
Reference Guide Correction
Description of change:
As of October 2014, a new calculator is available for the Minimum Indoor Air Quality Performance prerequisite. This correction includes the new calculator in the guidance for multiple-zone systems.
1. In Step-by-Step Guidance, Mechanically Ventilated Spaces (and Mixed-Mode Spaces When a Mechanical Ventilation is Active), [BD+C page 611, Step 2; ID+C page 311, Step 2; BO+M page 399, Step 4]
Replace the first sentence in last the bullet with the following: "For multiple-zone systems, use the calculator provided by USGBC or ASHRAE’s 62MZCalc Spreadsheet."
2. In Further Explanation, Calculations for Multiple-Zone Recirculating Systems [BD+C page 617; ID+C page 316; BO+M page 402]
Replace the first paragraph with the following: "Because of the complexity of the calculations for multiple-zone recirculating systems, project teams must use the calculator provided by USGBC, ASHRAE's 62MZCalc spreadsheet, or energy modeling software to perform the ventilation rate procedure calculations and determine the amount of outdoor air required at the system level."
3. In Further Explanation, Calculations for Multiple-Zone Recirculating Systems, System Ventilation Efficiency [BD+C page 617; ID+C page 317; BO+M page 402]
Replace the second and third paragraphs with the following: "The critical zone is the zone with the highest proportion of required outdoor air to provided supply air. Critical zones are often densely occupied spaces, such as conference rooms. If using the calculator provided by USGBC or ASHRAE’s 62MZCalc spreadsheet, when all zones are entered, the critical zone for the system is determined automatically.
For large projects, it may not be feasible to enter each individual zone. In these cases, the mechanical engineer can determine the outdoor air required for the system simply by identifying the potentially critical zone(s). For a detailed discussion of identifying critical zones, see ASHRAE Standard 62.1–2010, Appendix A–A3.1, Selecting Zones for Calculation, and ASHRAE 62.1–2010 User’s Manual, Example 6-L."
1. In Step-by-Step Guidance, Mechanically Ventilated Spaces (and Mixed-Mode Spaces When a Mechanical Ventilation is Active), [BD+C page 611, Step 2; ID+C page 311, Step 2; BO+M page 399, Step 4]
Replace the first sentence in last the bullet with the following: "For multiple-zone systems, use the calculator provided by USGBC or ASHRAE’s 62MZCalc Spreadsheet."
2. In Further Explanation, Calculations for Multiple-Zone Recirculating Systems [BD+C page 617; ID+C page 316; BO+M page 402]
Replace the first paragraph with the following: "Because of the complexity of the calculations for multiple-zone recirculating systems, project teams must use the calculator provided by USGBC, ASHRAE's 62MZCalc spreadsheet, or energy modeling software to perform the ventilation rate procedure calculations and determine the amount of outdoor air required at the system level."
3. In Further Explanation, Calculations for Multiple-Zone Recirculating Systems, System Ventilation Efficiency [BD+C page 617; ID+C page 317; BO+M page 402]
Replace the second and third paragraphs with the following: "The critical zone is the zone with the highest proportion of required outdoor air to provided supply air. Critical zones are often densely occupied spaces, such as conference rooms. If using the calculator provided by USGBC or ASHRAE’s 62MZCalc spreadsheet, when all zones are entered, the critical zone for the system is determined automatically.
For large projects, it may not be feasible to enter each individual zone. In these cases, the mechanical engineer can determine the outdoor air required for the system simply by identifying the potentially critical zone(s). For a detailed discussion of identifying critical zones, see ASHRAE Standard 62.1–2010, Appendix A–A3.1, Selecting Zones for Calculation, and ASHRAE 62.1–2010 User’s Manual, Example 6-L."
Campus Applicable
No
Internationally Applicable:
No
7/1/2014 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Step 4. Evaluate Compliance and Make Adjustments if Necessary- delete text at beginning of second paragraph ‘ASHRAE 62.1–2010, Section 6.5.’
Campus Applicable
Yes
Internationally Applicable:
Yes
10/1/2014 – Updated: 2/14/2015
Form Update
Description of change:
New calculator for projects performing the ASHRAE 62.1 ventilation rate procedure calculations required for EQ Prerequisite Minimum Indoor Air Quality Performance. This optional calculator can be used for LEED 2009 and LEED v4 projects and is an alternative to the ASHRAE 62.1 62MZCalc and previous 100% outdoor air and single zone calculators.
Campus Applicable
No
Internationally Applicable:
No
10/1/2015
LEED Interpretation
Inquiry:
Can cold storage areas conditioned below 32°F (0 °C) be excluded from the minimum ventilation requirements in the prerequisite Minimum Indoor Air Quality Performance? These spaces should be excluded for three reasons, 1. There are few contaminant sources in these spaces, 2. The introduction of outside air into these spaces is problematic, and 3. The storage areas are intended for storage of frozen goods and are uninhabitable environments, only occupied occasionally and for short periods of time, as dictated by OSHA requirements.
Ruling:
Yes, frozen cold storage areas conditioned below 32 °F (0 °C) do not need to meet ASHRAE 62.1 for the purposes of the Minimum Indoor Air Quality Prerequisite. This exception is not allowed for cold storage areas that can be adjusted from below 32 °F (0 °C) to above 32 °F (0 °C). It is also not allowed if combustion equipment (such as gas-operated forklifts) is operated in the space.
Campus Applicable
No
Internationally Applicable:
No
7/1/2015
LEED Interpretation
Inquiry:
May we use a more current version of ASHRAE 62.1 and ASHRAE 55?
Ruling:
Yes, for ASHRAE 62.1, LEED v4.1 projects may use ASHRAE 62.1-2019 or ASHRAE 62.1-2020 in lieu of ASHRAE 62.1-2016 for EQ Prerequisite Minimum Indoor Air Quality Performance and EQ Credit Enhanced Indoor Air Quality Strategies. The same standard must be used for both credits.
LEED v4 projects may use ASHRAE 62.1-2013, ASHRAE 62.1-2016, ASHRAE 62.1-2019, or ASHRAE 62.1-2020 in lieu of ASHRAE 62.1-2010 for EQ Prerequisite Minimum Indoor Air Quality Performance and EQ Credit Enhanced Indoor Air Quality Strategies. The same standard must be used for both credits.
LEED 2009 projects may use ASHRAE 62.1-2010, ASHRAE 62.1-2013, or ASHRAE 62.1-2016, ASHRAE 62.1-2019, or ASHRAE 62.1-2020 in lieu of ASHRAE 62.1-2007 for EQ Prerequisite Minimum Indoor Air Quality Performance and EQ Credit Increased Ventilation. The same standard must be used for both credits.
For ASHRAE 55, LEED v4.1 projects may use ASHRAE 55-2020 in lieu of ASHRAE 55-2017 for EQ Credit Thermal Comfort.
LEED v4 projects may use ASHRAE 55-2013 in lieu of ASHRAE 55-2010 for EQ Credit Thermal Comfort.
LEED 2009 projects may use ASHRAE 55-2010 or ASHRAE 55-2013 in lieu of ASHRAE 55-2004 for EQ Credit Thermal Comfort- Design.
**Updated 7/10/2020 to include ASHRAE 62.1-2016 and ASHRAE 62.1-2019 as applicable standards.**
**Updated 7/25/2023 to update to include LEED v4.1 and ASHRAE 2022/2020 standards**
Campus Applicable
No
Internationally Applicable:
No
4/6/2018
LEED Interpretation
Inquiry:
We are working to certify a 30 year old office tower. While we have copies of original mechanical design drawings and schedules, the building systems have experienced a number of retrofits over the years, and the as-built documentation is sparse. The ASHRAE 62.1-2007 ventilation rate procedure calculations for multiple zone systems rely on precision understanding of the ventilation zones (areas served by each terminal unit), zone airflow rates and VAV terminal unit minimum flow settings, and the system airflow rates. The extent to which the building must be surveyed and the systems tested to provide a high level of confidence in the VRP calculation inputs would be onerous and cost prohibitive. Without this survey information, the inputs to the calculator rely heavily on engineering judgement.
Can we instead use this simpler ventilation rate procedure calculation, to determine how much outdoor air should be supplied to the building?
Ventilation required in IP units = (0.06 cfm/sf x gross building area (in sf) ) + ( 5 cfm per person x building occupancy )
and ventilation required in SI units: = (0.3 L/s*m2 x gross building area (in m2)) + (2.5 L/s per person x building occupancy)
Ruling:
Yes, for office building projects, the proposed simplified calculation may be used. Other project types should use the appropriate Rp value from 62.1-2007, Table 6-1. Projects with multi-zone systems utilizing this simplified calculation approach should provide a supplemental narrative and may document the ventilation calculations as single zone systems within the EQ Minimum IAQ Performance Calculator.
The measured outdoor airflow rate for the building should be equal to or greater than the value calculated.
**Update for 1.11.19
A separate calculation must be performed for each air handling unit serving the project.
Campus Applicable
No
Internationally Applicable:
Yes
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© Copyright U.S. Green Building Council, Inc. All rights reserved.
Requirements
Establishment
Mechanically ventilated spaces
For mechanically ventilated spaces (and for mixed-mode systems when the mechanical ventilation is activated), chose one of the following:Case 1. Systems able to meet required outdoor airflow rates
Option 1. ASHRAE Standard 62.1-2010
Modify or maintain each outdoor air intake, supply air fan, and ventilation distribution system to meet the outdoor air intake flow rates, using the ASHRAE ventilation rate procedure or a local equivalent, whichever is more stringent and 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. [India ACP: Mechanically Ventilated]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.Case 2. Systems unable to meet required outdoor airflow rates
If meeting the outdoor airflow rates in Case 1 is not feasible because of the physical constraints of the existing ventilation system, complete an engineering assessment of the system’s maximum outdoor air delivery rate. Supply the maximum possible to reach the minimum setpoint in Case 1 and not less than 10 cubic feet per minute (5 liters per second) of outdoor air per person.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. [Europe ACP: Arbeitsstaettenrichtlinie ASR 5], [India ACP: Naturally Ventilated NBC] 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], [India ACP: Naturally Ventilated CPCB]All spaces
The indoor air quality procedure defined in ASHRAE Standard 62.1–2010 may not be used to comply with this prerequisite.
Performance
Show compliance through measurements taken at the system level within five years of the end of the performance period. Implement and maintain an HVAC system maintenance program, based on ASHRAE 62.1–2010, Section 8, or a local equivalent, whichever is more stringent, to ensure the proper operations and maintenance of HVAC components as they relate to outdoor air introduction and exhaust.Alternative Compliance Paths (ACPs)
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
- 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
- For single-zone and 100% outside air systems, National Building Code of India 2005 (NBC 2005) Table 4-air rate requirements in lieu of ASHRAE 62.1-2010 ventilation rate procedure. Only certain space types are eligible.
- Central Pollution Control Board (CPCB), National Ambient Air Quality Standards in lieu of ASHRAE 62.1-2010, Section 4.
- NBC 2005 Part 8, section 3, clause 3.2, with additional parameters, in lieu of ASHRAE 62.1-2010, Minimum Requirements, Sections 5-7.
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Continuous ventilation |
Intermittent ventilation |
|---|---|---|
|
Single-sided |
0,35 m² / person |
1,05 m² / 10 m² room area |
|
Cross-ventilation |
0,2 m² / person |
0,6 m² / 10 m² room area |
India ACP: Mechanically Ventilated
Projects in India may meet the following as a local equivalent to ASHRAE 62.1-2010:India ACP: Naturally Ventilated NBC
Projects in India may use NBC 2005 Part 8, Section 1, clauses 5.2.1-5.6 and Appendix A: Design for Natural Ventilation from Handbook on Functional Requirements of Buildings (other than Industrial Buildings), also known as SP 41, 1987 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure.India ACP: Naturally Ventilated CPCB
Projects in India may compare outdoor air quality with the CPCB National Ambient Air Quality Standards in lieu of the U.S. national air quality standards as required in ASHRAE Standard 62.1-2010, Section 4.Pilot Alternative Compliance Path Available
This credit has a pilot ACP available in the LEED Pilot Credit Library. See Indoor air quality procedure - alternative compliance path for more informationIn the end, LEED is all about documentation. LEEDuser’s Documentation Toolkit, for premium members only, saves you time and helps you avoid mistakes with:
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- Sample templates to help guide your narratives and LEED Online submissions.
- Examples of actual submissions from certified LEED projects.
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What happened to the IEQ Space Matrix that was available to version 2009 projects? What should I reference to determine how spaces in my building should be categorized for this prerequisite? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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How do I find whether my project is located in a non-attainment area for particulate matter or exceeds the prerequisite ozone requirements? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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The outdoor air intake for our ventilation system is not accessible, and it’s not possible to measure the outdoor airflow directly. How can we determine the outdoor airflow for this system? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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Our system cannot provide enough outdoor air to meet ASHRAE 62.1-2010 due to design limitations. How much outdoor air must we provide to meet Case 2 instead? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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My building has 80 AHUs providing ventilation to building spaces. Do I have to do the ventilation calculations and conduct outdoor air measurements for each one? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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What if after our Preliminary Review we have to revise the ventilation rate procedure calculations and find that we need to make corrections to the system in order to meet the prerequisite? Can we redo the outside air testing after making corrections? Would we need to update the performance period for all credits accordingly? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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What if our systems do not meet the required outside air when systems are tested at worst-case conditions? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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Our building has a single fan that supplies outside air to multiple AHUs. Do we need to perform outside air testing at the supply fan or at all AHUs? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
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We have a VAV system where single AHUs serve multiple zones. Do we need to take outside air measurements at each VAV box? The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
4/6/2018 – Updated: 11/6/2020
Regional ACP
Description of change:
Table 1. Minimum ventilation area
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Campus Applicable
No
Internationally Applicable:
No
7/8/2017 – Updated: 11/6/2020
Regional ACP
Description of change:
Revise the Europe ACP to the following:
"Projects in Europe may use Arbeitsstaettenrichtlinie ASR 5 or ASR A3.6 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure."
"Projects in Europe may use Arbeitsstaettenrichtlinie ASR 5 or ASR A3.6 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure."
Campus Applicable
No
Internationally Applicable:
No
4/6/2018 – Updated: 11/6/2020
Reference Guide Correction
Description of change:
Table 1. Minimum ventilation area
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Campus Applicable
No
Internationally Applicable:
No
4/1/2015 – Updated: 3/29/2018
Regional ACP
Description of change:
After the first paragraph add the following:
Projects in India may meet the following as a local equivalent to ASHRAE 62.1-2010:
- For single-zone and 100% outside air systems, National Building Code of India 2005 (NBC 2005) Table 4-air rate requirements in lieu of ASHRAE 62.1-2010 ventilation rate procedure. Only certain space types are eligible.
- Central Pollution Control Board (CPCB), National Ambient Air Quality Standards in lieu of ASHRAE 62.1-2010, Section 4.
- NBC 2005 Part 8, section 3, clause 3.2, with additional parameters, in lieu of ASHRAE 62.1-2010, Minimum Requirements, Sections 5-7.
Projects in India may meet the following as a local equivalent to ASHRAE 62.1-2010:
- For single-zone and 100% outside air systems, National Building Code of India 2005 (NBC 2005) Table 4-air rate requirements in lieu of ASHRAE 62.1-2010 ventilation rate procedure. Only certain space types are eligible.
- Central Pollution Control Board (CPCB), National Ambient Air Quality Standards in lieu of ASHRAE 62.1-2010, Section 4.
- NBC 2005 Part 8, section 3, clause 3.2, with additional parameters, in lieu of ASHRAE 62.1-2010, Minimum Requirements, Sections 5-7.
Campus Applicable
No
Internationally Applicable:
Yes
4/1/2015 – Updated: 3/29/2018
Regional ACP
Description of change:
After the first paragraph add the following:
"Projects in India may use NBC 2005 Part 8, Section 1, clauses 5.2.1-5.6 and Appendix A: Design for Natural Ventilation from Handbook on Functional Requirements of Buildings (other than Industrial Buildings), also known as SP 41, 1987 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure."
After the second paragraph add the following:
"Projects in India may compare outdoor air quality with the CPCB National Ambient Air Quality Standards in lieu of the U.S. national air quality standards as required in ASHRAE Standard 62.1-2010, Section 4."
"Projects in India may use NBC 2005 Part 8, Section 1, clauses 5.2.1-5.6 and Appendix A: Design for Natural Ventilation from Handbook on Functional Requirements of Buildings (other than Industrial Buildings), also known as SP 41, 1987 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure."
After the second paragraph add the following:
"Projects in India may compare outdoor air quality with the CPCB National Ambient Air Quality Standards in lieu of the U.S. national air quality standards as required in ASHRAE Standard 62.1-2010, Section 4."
Campus Applicable
No
Internationally Applicable:
Yes
7/1/2016 – Updated: 7/15/2016
Reference Guide Correction
Description of change:
Revise the bullet "BAS data for minimum outdoor air setpoints" to "Minimum outdoor air setpoints"
Campus Applicable
No
Internationally Applicable:
No
6/3/2016 – Updated: 6/3/2016
Form Update
Description of change:
1. Fixed bug with default values for zone population in the single zone sheet
2. Updated Table 6-3 calculation for Ev in the multiple zone sheet to not exceed 1.0 when Max Zp3. In multiple zone sheet, changed Ep from user entry to calculated value.
4. Added column for Zone outdoor airflow provided to the 100% OA and corresponding column in the summary tab (zone outdoor airflow provided meets or exceeds Voz for all zones).
5. Note added to Are you using default value for zone population to clarify default values should only be used if expected occupancy is unknown.
6. Modified rounding and decimals displayed
7. Fixed bug in summary sheet so that all systems are always displayed.
2. Updated Table 6-3 calculation for Ev in the multiple zone sheet to not exceed 1.0 when Max Zp3. In multiple zone sheet, changed Ep from user entry to calculated value.
4. Added column for Zone outdoor airflow provided to the 100% OA and corresponding column in the summary tab (zone outdoor airflow provided meets or exceeds Voz for all zones).
5. Note added to Are you using default value for zone population to clarify default values should only be used if expected occupancy is unknown.
6. Modified rounding and decimals displayed
7. Fixed bug in summary sheet so that all systems are always displayed.
Campus Applicable
No
Internationally Applicable:
No
4/1/2015 – Updated: 4/7/2016
Regional ACP
Description of change:
Add the following after the text for Naturally Ventilated Spaces:
"Projects in Europe may use Arbeitsstaettenrichtlinie ASR 5 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure."
"Projects in Europe may use Arbeitsstaettenrichtlinie ASR 5 as a local equivalent to ASHRAE Standard 62.1-2010, natural ventilation procedure."
Campus Applicable
No
Internationally Applicable:
Yes
4/1/2015 – Updated: 4/16/2015
Form Update
Description of change:
Revised form to include India ACP for mechanically ventilated space (Case 1) and naturally ventilated spaces.
Campus Applicable
No
Internationally Applicable:
Yes
4/1/2015 – Updated: 4/1/2015
Reference Guide Correction
Description of change:
As of October 2014, a new calculator is available for the Minimum Indoor Air Quality Performance prerequisite. This correction includes the new calculator in the guidance for multiple-zone systems.
1. In Step-by-Step Guidance, Mechanically Ventilated Spaces (and Mixed-Mode Spaces When a Mechanical Ventilation is Active), [BD+C page 611, Step 2; ID+C page 311, Step 2; BO+M page 399, Step 4]
Replace the first sentence in last the bullet with the following: "For multiple-zone systems, use the calculator provided by USGBC or ASHRAE’s 62MZCalc Spreadsheet."
2. In Further Explanation, Calculations for Multiple-Zone Recirculating Systems [BD+C page 617; ID+C page 316; BO+M page 402]
Replace the first paragraph with the following: "Because of the complexity of the calculations for multiple-zone recirculating systems, project teams must use the calculator provided by USGBC, ASHRAE's 62MZCalc spreadsheet, or energy modeling software to perform the ventilation rate procedure calculations and determine the amount of outdoor air required at the system level."
3. In Further Explanation, Calculations for Multiple-Zone Recirculating Systems, System Ventilation Efficiency [BD+C page 617; ID+C page 317; BO+M page 402]
Replace the second and third paragraphs with the following: "The critical zone is the zone with the highest proportion of required outdoor air to provided supply air. Critical zones are often densely occupied spaces, such as conference rooms. If using the calculator provided by USGBC or ASHRAE’s 62MZCalc spreadsheet, when all zones are entered, the critical zone for the system is determined automatically.
For large projects, it may not be feasible to enter each individual zone. In these cases, the mechanical engineer can determine the outdoor air required for the system simply by identifying the potentially critical zone(s). For a detailed discussion of identifying critical zones, see ASHRAE Standard 62.1–2010, Appendix A–A3.1, Selecting Zones for Calculation, and ASHRAE 62.1–2010 User’s Manual, Example 6-L."
1. In Step-by-Step Guidance, Mechanically Ventilated Spaces (and Mixed-Mode Spaces When a Mechanical Ventilation is Active), [BD+C page 611, Step 2; ID+C page 311, Step 2; BO+M page 399, Step 4]
Replace the first sentence in last the bullet with the following: "For multiple-zone systems, use the calculator provided by USGBC or ASHRAE’s 62MZCalc Spreadsheet."
2. In Further Explanation, Calculations for Multiple-Zone Recirculating Systems [BD+C page 617; ID+C page 316; BO+M page 402]
Replace the first paragraph with the following: "Because of the complexity of the calculations for multiple-zone recirculating systems, project teams must use the calculator provided by USGBC, ASHRAE's 62MZCalc spreadsheet, or energy modeling software to perform the ventilation rate procedure calculations and determine the amount of outdoor air required at the system level."
3. In Further Explanation, Calculations for Multiple-Zone Recirculating Systems, System Ventilation Efficiency [BD+C page 617; ID+C page 317; BO+M page 402]
Replace the second and third paragraphs with the following: "The critical zone is the zone with the highest proportion of required outdoor air to provided supply air. Critical zones are often densely occupied spaces, such as conference rooms. If using the calculator provided by USGBC or ASHRAE’s 62MZCalc spreadsheet, when all zones are entered, the critical zone for the system is determined automatically.
For large projects, it may not be feasible to enter each individual zone. In these cases, the mechanical engineer can determine the outdoor air required for the system simply by identifying the potentially critical zone(s). For a detailed discussion of identifying critical zones, see ASHRAE Standard 62.1–2010, Appendix A–A3.1, Selecting Zones for Calculation, and ASHRAE 62.1–2010 User’s Manual, Example 6-L."
Campus Applicable
No
Internationally Applicable:
No
7/1/2014 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Step 4. Evaluate Compliance and Make Adjustments if Necessary- delete text at beginning of second paragraph ‘ASHRAE 62.1–2010, Section 6.5.’
Campus Applicable
Yes
Internationally Applicable:
Yes
10/1/2014 – Updated: 2/14/2015
Form Update
Description of change:
New calculator for projects performing the ASHRAE 62.1 ventilation rate procedure calculations required for EQ Prerequisite Minimum Indoor Air Quality Performance. This optional calculator can be used for LEED 2009 and LEED v4 projects and is an alternative to the ASHRAE 62.1 62MZCalc and previous 100% outdoor air and single zone calculators.
Campus Applicable
No
Internationally Applicable:
No
10/1/2015
LEED Interpretation
Inquiry:
Can cold storage areas conditioned below 32°F (0 °C) be excluded from the minimum ventilation requirements in the prerequisite Minimum Indoor Air Quality Performance? These spaces should be excluded for three reasons, 1. There are few contaminant sources in these spaces, 2. The introduction of outside air into these spaces is problematic, and 3. The storage areas are intended for storage of frozen goods and are uninhabitable environments, only occupied occasionally and for short periods of time, as dictated by OSHA requirements.
Ruling:
Yes, frozen cold storage areas conditioned below 32 °F (0 °C) do not need to meet ASHRAE 62.1 for the purposes of the Minimum Indoor Air Quality Prerequisite. This exception is not allowed for cold storage areas that can be adjusted from below 32 °F (0 °C) to above 32 °F (0 °C). It is also not allowed if combustion equipment (such as gas-operated forklifts) is operated in the space.
Campus Applicable
No
Internationally Applicable:
No
7/1/2015
LEED Interpretation
Inquiry:
May we use a more current version of ASHRAE 62.1 and ASHRAE 55?
Ruling:
Yes, for ASHRAE 62.1, LEED v4.1 projects may use ASHRAE 62.1-2019 or ASHRAE 62.1-2020 in lieu of ASHRAE 62.1-2016 for EQ Prerequisite Minimum Indoor Air Quality Performance and EQ Credit Enhanced Indoor Air Quality Strategies. The same standard must be used for both credits.
LEED v4 projects may use ASHRAE 62.1-2013, ASHRAE 62.1-2016, ASHRAE 62.1-2019, or ASHRAE 62.1-2020 in lieu of ASHRAE 62.1-2010 for EQ Prerequisite Minimum Indoor Air Quality Performance and EQ Credit Enhanced Indoor Air Quality Strategies. The same standard must be used for both credits.
LEED 2009 projects may use ASHRAE 62.1-2010, ASHRAE 62.1-2013, or ASHRAE 62.1-2016, ASHRAE 62.1-2019, or ASHRAE 62.1-2020 in lieu of ASHRAE 62.1-2007 for EQ Prerequisite Minimum Indoor Air Quality Performance and EQ Credit Increased Ventilation. The same standard must be used for both credits.
For ASHRAE 55, LEED v4.1 projects may use ASHRAE 55-2020 in lieu of ASHRAE 55-2017 for EQ Credit Thermal Comfort.
LEED v4 projects may use ASHRAE 55-2013 in lieu of ASHRAE 55-2010 for EQ Credit Thermal Comfort.
LEED 2009 projects may use ASHRAE 55-2010 or ASHRAE 55-2013 in lieu of ASHRAE 55-2004 for EQ Credit Thermal Comfort- Design.
**Updated 7/10/2020 to include ASHRAE 62.1-2016 and ASHRAE 62.1-2019 as applicable standards.**
**Updated 7/25/2023 to update to include LEED v4.1 and ASHRAE 2022/2020 standards**
Campus Applicable
No
Internationally Applicable:
No
4/6/2018
LEED Interpretation
Inquiry:
We are working to certify a 30 year old office tower. While we have copies of original mechanical design drawings and schedules, the building systems have experienced a number of retrofits over the years, and the as-built documentation is sparse. The ASHRAE 62.1-2007 ventilation rate procedure calculations for multiple zone systems rely on precision understanding of the ventilation zones (areas served by each terminal unit), zone airflow rates and VAV terminal unit minimum flow settings, and the system airflow rates. The extent to which the building must be surveyed and the systems tested to provide a high level of confidence in the VRP calculation inputs would be onerous and cost prohibitive. Without this survey information, the inputs to the calculator rely heavily on engineering judgement.
Can we instead use this simpler ventilation rate procedure calculation, to determine how much outdoor air should be supplied to the building?
Ventilation required in IP units = (0.06 cfm/sf x gross building area (in sf) ) + ( 5 cfm per person x building occupancy )
and ventilation required in SI units: = (0.3 L/s*m2 x gross building area (in m2)) + (2.5 L/s per person x building occupancy)
Ruling:
Yes, for office building projects, the proposed simplified calculation may be used. Other project types should use the appropriate Rp value from 62.1-2007, Table 6-1. Projects with multi-zone systems utilizing this simplified calculation approach should provide a supplemental narrative and may document the ventilation calculations as single zone systems within the EQ Minimum IAQ Performance Calculator.
The measured outdoor airflow rate for the building should be equal to or greater than the value calculated.
**Update for 1.11.19
A separate calculation must be performed for each air handling unit serving the project.
Campus Applicable
No
Internationally Applicable:
Yes
LEEDuser expert
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WSP - Built Ecology
Senior Sustainability Manager
