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LEED v2009
Existing Building Operations
Indoor Environmental Quality
Minimum IAQ Performance

LEED CREDIT

EBOM-2009 IEQp1: Minimum indoor air quality performance Required

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Requirements

Case 1. Projects able to meet the standard
OPTION 1. ASHRAE Standard 62.1-2007 or Non-U.S. Equivalent
Modify or maintain each outside air intake, supply air fan and/or ventilation distribution system to supply at least the outdoor air ventilation rate required by ASHRAE Standard 62.1–2007 ventilation rate procedure (with errata but without addenda ) under all normal operating conditions. Projects outside the U.S. may use a local equivalent to ASHRAE Standard 62.1-2007 for breathing zone minimum ventilation rates.
OPTION 2. CEN Standard EN 15251: 2007
Projects outside the U.S. may modify or maintain each outside air intake, supply air fan and/or ventilation distribution system to supply at least the outdoor air ventilation rate required by 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.
Case 2. Projects unable to meet the standard
If meeting the ventilation rates required of the above standards is infeasible because of the physical constraints of the existing ventilation system, modify or maintain the system to supply at least 10 cubic feet per minute (cfm) (5 liters per second) of outdoor air per person under all normal operating conditions. Demonstrate through design documentation, measurements or other evidence that the current system cannot provide the flow rates required by the above standards under any operating condition even when functioning properly. Each air-handling unit in the building must comply with either Case 1 or Case 2. If some airhandling units can provide the outside air flow required by the above standards and others cannot, those that can must do so. Buildings must provide at least 10 cfm (5 liters per second) per person of outside air at each air-handling unit under all normal operating conditions to earn this prerequisite.
  • Show compliance with the applicable requirement above (Case 1 or Case 2) through measurements taken at the system level (i.e., the air-handling unit). For variable air volume systems, the dampers, fan speeds, etc. must be set during the test to the worstcase system conditions (minimum outside air flow) expected during normal ventilation operations. Each air-handler must be measured; sampling or grouping of air-handlers is prohibited.
  • Implement and maintain an HVAC system maintenance program to ensure the proper operations and maintenance of HVAC components as they relate to outdoor air introduction and exhaust.
  • Test and maintain the operation of all building exhaust systems, including bathroom, shower, kitchen and parking exhaust systems.
Naturally ventilated buildings must comply with ASHRAE Standard 62.1-2007, paragraph 5.1(with errata but without addenda1). [Europe ACP: Arbeitsstaettenrichtlinie ASR 5]

Alternative Compliance Paths (ACPs)

Europe ACP: Arbeitsstaettenrichtlinie ASR 5
Projects in Europe may use Arbeitsstaettenrichtlinie ASR 5 or ASR A3.6 as a local equivalent to ASHRAE Standard 62.1-2007, paragraph 5.1.
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 information
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Frequently asked questions

What if after our Preliminary Review we have to re-work 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?

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What if our systems do not meet the required outside air when systems are tested at worst-case conditions?

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Our building has a single fan that supplies outside air to multiple AHU’s. Do we need to perform outside air testing at the supply fan or at all AHUs?

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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?

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Addenda

7/8/2017Updated: 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."
Campus Applicable
No
Internationally Applicable:
No
4/1/2015Updated: 4/1/2015
Regional ACP
Description of change:
Add the following after the text for Case 2:

"Projects in Europe may use Arbeitsstaettenrichtlinie ASR 5 as a local equivalent to ASHRAE Standard 62.1-2007, paragraph 5.1."
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Option 2 should read: "Projects outside the U.S. may modify or maintain each outside air intake, supply air fan and/or ventilation distribution system to supply at least the outdoor air ventilation rate required by Annex B of Comit
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Case 1 should read: "CASE 1. Projects Able to Meet Standard"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add new Option title that reads: "OPTION 1. ASHRAE Standard 62.1-2007 or Non-U.S. Equivalent"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Delete the Alternative Compliance Path for Projects Outside the U.S.
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
The first paragraph of case 2 should read: "If meeting the ventilation rates required of the above standards is infeasible because of the physical constraints of the existing ventilation system, modify or maintain the system to supply at least 10 cubic feet per minute (cfm) (5 liters per second) of outdoor air per person under all normal operating conditions. Demonstrate through design documentation, measurements or other evidence that the current system cannot provide the flow rates required by the above standards under any operating condition even when functioning properly."
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Case 2 should read: "CASE 2. Projects Unable to Meet the Standard"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
"Ventilation Rate Procedure" should be changed to "ventilation rate procedure"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add new Option title that reads: "OPTION 2. CEN Standard EN 15251: 2007"
Campus Applicable
No
Internationally Applicable:
Yes
4/14/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the text with "Breathing zone is the region within an occupied space between 3 and 6 feet above the floor. Note that this definition varies from that of ASHRAE 62.1-2007, which states that the breathing zone is between 3 inches and 6 feet from the floor, and 2 feet from the walls as well as fixed air conditioning equipment."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
In the second paragraph of case 2 replace "ASHRAE Standard 62.1-2007 (with errata but without addenda)" with "the above standards"
Campus Applicable
No
Internationally Applicable:
Yes
10/1/2014Updated: 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
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
In the second paragraph of case 2 replace "4.72" with "5"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Option 1 should include the original paragraph for case 1 with the following sentence at the end: "Projects outside the U.S. may use a local equivalent to ASHRAE Standard 62.1-2007 for breathing zone minimum ventilation rates."
Campus Applicable
No
Internationally Applicable:
Yes
3/25/2008
LEED Interpretation
Inquiry:

Our project is a 95,000 sf, 150 year old, Mill composed of multiple adjoining buildings. When certified, it is our understanding, that this building will be the oldest LEED certified building. The last major renovation of the building was roughly 30 years ago when we first occupied it. There have been minor renovations since then. The mechanical system is complex due to the nature of a 150 year old building and the many adaptations that happen over time. It is comprised of over 30 air-handling units. Between operable windows and the existing mechanical system 88% of the building\'s square feet meet the credit requirements for ventilation rates prescribed in ASHRAE 90.1 2004 or meet at least 10 cfm per person in areas where it is not possible to upgrade the system due to physical constraints. We have a signed contract to perform work to bring the remaining 12% of the space up to ASHRAE 90.1 2004 ventilation rates. Modifying an existing building\'s outside air distribution system to supply at least the outdoor air ventilation rates required by ASHRAE 62.1 2004 can be a lengthy process considering time to procure materials and labor. The credit implies that the system modifications and readings must be completed prior to submitting for project certification. Other prerequisites have options for plans to comply within a timeframe instead of demonstrating full compliance. LEED NC 2.2 EA PR 3 allows for a 5 year phase-out plan for CFCs in an existing facility and LEED EB 2.0 PR 3&4 allow asbestos and pcb management plans as opposed to complete removal of those substances. In regards to LEED EB 2.0 EQ PR1, we propose that if less than 25% of the building sf requires system modifications, due to the complexity of an existing building, then a plan to complete the modifications within three months will satisfy this credit. The documentation will include a signed contract by the owner and the mechanical contractor to complete the work within the three month period. Please confirm that this approach will satisfy LEEB EB 2.0 EQ PR1.

Ruling:

What you have proposed above is not acceptable to earn LEED-EBv2.0 EQp1. Outside air ventilation performance testing measurement are required for all of the existing building\'s Air Handling Units at the time of LEED-EB building certification application submittal. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
2/24/2009
LEED Interpretation
Inquiry:

We are inquiring about the approach for measuring outdoor airflow in our building to satisfy the requirements of EQp1. The building is a 47-story commercial office tower completed in 1981. It has a main air handling system to serve the office floors with a central outdoor air shaft inside the core of the building with openings at the top and bottom. Each floor has a supply air fan that draws air from the shaft and mixes it with return air. We are proposing to measure the total outdoor air intake flow for the central air shaft at the two intakes to the shaft (e.g. with a pitot tube traverse at the top and bottom), and compare this to the required CFM of outdoor air for the total square footage served as determined by the ASHRAE 62.1 calculator. EQp1 requires measurements "at the system level (i.e. the air-handling unit). each air handling unit must be measured." We propose that our outdoor air shaft is essentially a measureable system that meets the requirements. We would note that buildings with a similar supply air shaft and a central supply fan (which is a common arrangement) would be required to measure the input to the shaft; our proposed measurements should give the same level of detail about availability of outdoor air to building occupants as would be achieved in that case. While this is not essential to our proposal, it is worth noting that because of the very compact layout of the mechanical room it is very difficult to take a reasonably accurate reading of air flow on the floor-by-floor equipment-- the return air damper is immediately adjacent to the outdoor air damper, there are no straight duct runs adjacent to the supply air fan, and there is no access to the central outdoor air shaft. We believe our proposal will be more accurate than measurements on our floor fans taken with these constraints. We would also note that the building contains street-level retail spaces and a lobby that are not served by this main shaft. We would like to confirm that these spaces do not need to be measured because the lobby does not contain any regularly occupied space and the retail spaces are served by tenant owned and operated systems that the building management does not control. The retail spaces would fall under the 10% area exclusion for multi-tenant buildings explained on page 23 of the reference guide that states that all prerequisites "address base building systems or are limited to areas under management control."

Ruling:

Project teams must demonstrate that each outside air intake, supply air fan, and/or ventilation distribution system supplies the minimum OA ventilation specified by ASHRAE 62.1-2007. Based on the system description provided for this facility, measuring air intake flow for the central air shaft does not meet this requirement. Spaces under separate management, such as the retail spaces described here, may be excluded from calculations and measurements if they comprise less than 10% of the building\'s floor area. Aside from this exclusion for relatively small spaces under separate management, all occupiable spaces must be accounted for by the calculations and measurements. This includes lobby areas, which meets ASHRAE\'s definition of occupiable space: enclosed spaced intended for human activities. Only unoccupiable spaces such as equipment rooms or certain storage rooms can be excluded. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
8/1/2011
LEED Interpretation
Inquiry:

This project is a renovation of an existing building on a university campus. This building is one of a series of buildings constructed in the early 1960\'s, and the University is attempting to maintain the character and cohesiveness of the campus by preserving the existing structures and facades. Preserving the buildings also contributes to our sustainable design efforts, but it has resulted in an issue with the prerequisite for indoor air quality. The basement and first floor levels are mechanically ventilated in accordance with ASHRAE 62.1, and do not present a problem. However, running ductwork to the upper floors did prove problematic, so the design team is relying upon natural ventilation for the second and third floors. After calculating the window ventilation areas, all but three of the rooms comply with ASHRAE 62.1 for natural ventilation. The three rooms in question obtain 74%, 77% and 78% of the required ventilation area for operable windows.In order to meet University requirements and LEED Criteria all windows will be replaced with new, energy star models, to match the size and appearance of the existing windows. As previously mentioned, these new windows will generally provide 100% opening requirements, except in the three cases noted.It is the University\'s intent, as the Authority Having Jurisdiction, to grant a waiver for the minimum ventilation requirement in only these three rooms, thereby permitting the maximum use of the facility, while maintaining the historic appearance of the building.The University has therefore requested an interpretation from USGBC that this waiver for reduced ventilation requirements will be acceptable for obtaining LEED Certification for these facilities.

Ruling:

The applicant is requesting a waiver from the ASHRAE 62.1-2007 Section 5.1 natural ventilation prescriptive requirements for three rooms within the existing building. The new window areas are insufficient to meet the prescriptive requirements and are specified and installed per university requirements. ASHRAE 62.1-2007 exempts engineered natural ventilation systems when approved by the authority having jurisdiction. The natural ventilation system, as described, does not appear to be an engineered system. In this case, the prescriptive requirements could not be waived.

Campus Applicable
No
Internationally Applicable:
No
10/1/2012
LEED Interpretation
Inquiry:

We are meeting the IEQp1: Minimum Indoor Air Quality Performance with Option 2, CEN standards EN 15251:2007 and EN 13779:2007. The CEN standards provide minimum outdoor air requirements for most spaces but refer to local codes for certain specialty spaces such as parking garages. To meet the intent of the prerequisite, we propose using our local code requirements for garages, which is Teil 5 Garagen (“Section 5 – Parking Garages”) of the Verordnung über Bau und Betrieb von Sonderbauten - Nordrhein-Westfalen (“Local Law of North Rhine-Westphalia for the Construction and Operation of Specialty Buildings”), dated 17 November 2009 (SBauVO). To meet this local code, our design will use demand control ventilation with carbon monoxide (CO) detectors to limit the CO concentration. Is this approach acceptable?

Ruling:

**Update 10/01/2014: Ruling has been revised
Yes, garage demand control ventilation is an acceptable ventilation approach for parking garages. This approach is acceptable for projects pursuing Option 2 (EN 15251 and EN 13779) of EQ Prerequisite Minimum Indoor Air Quality Performance as well as the hazardous exhaust requirements in EQ Credit Indoor Chemical and Pollutant Source Control. The demand control ventilation strategy must meet the following requirements:

  • • Consider the number of cars expected to be operating in the garage at any given time and the length of time a car remains in operation in the parking garage.
  • • Consider the emission rates associated with the car exhaust for the average car.
  • • Detect the primary contaminant(s) of concern in the parking garage (for example: carbon monoxide, particulates, VOCs, NO2, etc.).
  • • Modulate airflow such that contaminant levels are maintained below a specified contaminant concentration limit and corresponding exposure period. All concentration limits must be based on local code or some other cognizant authority. If the contaminant is carbon monoxide, a concentration limit of 35 ppm time-weighted average (8 hours) and levels not to exceed 50 ppm at any time is recommended.
Campus Applicable
No
Internationally Applicable:
Yes
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
4/1/2012
LEED Interpretation
Inquiry:

Can projects use the natural ventilation prescriptive dimensional requirements written in 62.1-2010, instead of those in ASHRAE 62.1-2007? This would allow some spaces to comply with the requirements where they may otherwise not if 62.1-2007 is applied. If so, are we required to comply with the standard as a whole? Applying the standard as whole would have serious implications for new construction or existing projects attempting to comply with the Natural Ventilation Procedure because in some instances mechanical ventilation systems would have to be installed to meet the prerequisite.

Ruling:

For LEED 2009 projects where ASHRAE 62.1-2007 is the applicable standard for compliance with IEQp1, project teams may substitute the geometric requirements of ASHRAE 62.1-2010 sections 6.4.1 through 6.4.2 in place of ASHRAE 62.1-2007 section 5.1.1.
**Update October 1, 2013: This ruling also applies to EQp1 in LEED 2009 for Schools.

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 projects may use ASHRAE 62.1-2013, ASHRAE 62.1-2016 or ASHRAE 62.1-2019 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, or ASHRAE 62.1-2019 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 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.**

Campus Applicable
No
Internationally Applicable:
No
2/12/2008
LEED Interpretation
Inquiry:

Description We are planning to construct an apparel factory for LEED certification. The planned factory will have 1000 sewing machines and few finishing equipments among others. The entire space will be air conditioned to maintain ASHRAE comfort levels. The occupation density is 20-25 persons per 1000 square feet. Proposal Since there is no specified category in ASHRAE 62.1-2004 \'Ventilation for Acceptable Indoor Air Quality\' for apparel industry, we are proposing to use \'data entry\' category listed under office buildings which is similar (200W sewing machine with operator seated similar to data entry). This allows 5cfm per person with 0.06cfm per square feet. Please rule on the acceptability of this approach.

Ruling:

The CIR is asking for verification that they have selected the appropriate Occupancy Category for their project, given that it does not fall precisely within the categories listed in ASHRAE 62.1-2004. ASHRAE instructs that if the occupancy category for a proposed space or zone is not listed, the requirements for the listed occupancy category that is most similar in terms of occupant density, activities and building construction shall be used. It is up to the discretion of the design team to select the most appropriate alternative. It would be beneficial to the LEED reviewer if, included with the prerequisite submission, the applicant provides an explanation of their rationale for the selection. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
9/23/2008
LEED Interpretation
Inquiry:

There is certain language in the prerequisite description that appears to apply to a specific type of HVAC system that is not present in this building. Specifically, the language stating that each "air handling unit in the building must comply with either Option A or Option B" assumes that all buildings have air handling units. This building does not have air handling units. The design is that of approximately 150 heat pumps with individual zone temperature control and ducted outside air through a single make-up air handling unit located on the roof. On each floor there is a takeoff from the main outside air riser with a ducted outside air distribution loop that delivers outside air to each heat pump. Verifying the outside airflow at each heat pump, as if each heat pump is an independent air handling unit, is cost prohibitive and places our LEED application at an undue disadvantage in comparison with a building with contemporary variable air volume (VAV) air handling units or other zone level control. Furthermore, the use of the terminology of air handling unit being the primary source of outside air is in conflict with the description under option A that provides for verification of "each outside air intake, supply air fan AND/OR ventilation distribution system to supply at least the outdoor air ventilation rate required by ASHRAE 62.1-2007." We believe that the terminology that is applicable in the design of the HVAC systems at these buildings is more consistent with Option A verification requirements, i.e., ventilation distribution system. Furthermore, the requirement for verification of outside air ventilation at each "air handling unit" would not apply since it represents an inconsistent requirement for buildings with heat pumps versus a building with floor level air handling units and zone level terminal VAVs. We request that the following scope of services be considered an acceptable procedure for outside air verification and satisfaction EQ Prerequisite 1. 1. Perform duct traverses at the takeoffs from the main outside air makeup unit supply riser. The traverse shall provide data on the outside air velocity pressure and airflow (CFM) for the ducted "ventilation distribution system" that delivers outside air to the terminal heat pumps. These measurements shall be performed on every floor ventilation air distribution system (9 floors per building). These measurements shall be performed with the 400 Brand make-up air VFD at 60 Hz at its normal operating condition (unit is constant speed without VFD). This approach will provide for 100% of the building outside air delivery on a floor by floor basis. It is believed that this approach is comparable to measuring outside air at a single air handler in a system design where each floor is served by a single air handler. 2. Perform airflow measurements at the main make-up air unit on the roof of building. The VFD shall be set at 60 Hz for the preliminary measurement. These measurements shall be displayed in a final report in a comparative manner with the summation of the individual floor level ventilation air distribution systems. 3. Perform pressure measurements across the fan and across various turns and obstructions prior to the building riser. The VFD shall be set at 60 Hz for the preliminary measurement. 4. Provide measurements of the exhaust air from the ducting for each of the restroom exhaust ducts on each of the 9 floors. 5. Perform airflow measurements at the main exhaust air unit on the roof. The VFDs shall be set at the typical operating speed and at 60 Hz. At both settings, on each of the exhaust fans, conduct airflow and pressure measurements.

Ruling:

The measurement approach explained in steps 1-3 above, based on the information provided for the system under consideration, appears appropriate for demonstrating the OA volume to the project building. In general, project teams should develop a measurement protocol suited to the air handling and distribution system that is in accordance with SMACNA\'s HVAC Systems - Testing, Adjusting and Balancing, or equivalent at least to the extent necessary to verify conformations with the total outdoor air flow and space supply air flow requirements of ASHRAE 62.1. Please note that Ventilation Rate Procedure calculations should factor in zone ventilation efficiency (Evz), as appropriate. This factor modifies the required outdoor air based on the efficiency with which a system distributes outdoor air from the intake to an individual breathing zone (in the case the zone served by each heat pump). Steps 4-5 describe a procedure for testing exhaust systems. Exhaust system steps should confirm proper exhaust function, such as fan speed, voltage, control sequences, and set points as applicable. Airflow measurements is one option for demonstrating proper function, though there may be simpler testing options available to the project team.

Campus Applicable
No
Internationally Applicable:
No
11/11/2008
LEED Interpretation
Inquiry:

The project building contains 40 AHUs which are each monitored and regulated based on CO2 differential rather than outdoor air introduction. In lieu of documenting a measurement of outdoor airflow at each AHU, the project team proposes to show compliance with the outdoor air ventilation rate required by ASHRAE 62.1-2007 by documenting the differential between the CO2 level in each AHU\'s return duct and the CO2 level in the outdoor environment. The correlation between the differential CO2 readings and the ventilation rate per person is described in Appendix C of the ASHRAE 62.1-2007 standard while Section 6.2.7 of ASHRAE 62.1-2007 supports the project team\'s use of CO2 differential to maintain an average ventilation rate per occupant in each zone. The project building utilizes a demand ventilation control sequence which was adapted to an existing outdoor air delivery system with motorized dampers that adjust the volume of outside air that is delivered to each zone. Damper adjustment is based on the differential between the CO2 levels in the return air duct and the CO2 levels in the outdoor environment. The control sequence utilizes a PID loop to help anticipate the volume of air required rather than try to catch up as the levels of CO2 increase on the floor.

Ruling:

Because the Ventilation Rate Procedure stipulates outdoor air levels adequate to address both bioeffluents from the building\'s populations and air contaminants off-gassing from the building itself, showing that CO2 concentrations are held within a certain level relative to outdoor CO2 levels per Appendix C of the standard is not sufficient for demonstrating compliance with the standard in an existing building. The above approach addresses only the occupancy-related ventilation requirements. To show compliance with the requirements, assessment of the total volume of outdoor air delivered to each ventilation zone is required. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011
LEED Interpretation
Inquiry:

How do naturally ventilated projects, such as high rise residential projects, that do not qualify with the requirements of the Ventilation Rate Procedure, or ASHRAE 62.1 Section 5.1, or CIBSE Applications Manual 10 meet IEQp1 for v2 and 2009 rating systems?

Ruling:

For projects that do not qualify with the requirements of the Ventilation Rate Procedure, or ASHRAE 62.1 Section 5.1, or CIBSE Applications Manual 10, and are pursuing an engineered ventilation system (e.g. a combination of natural ventilation with mechanical exhaust, or some other means of assisting the outside airflow through the openings and circulating it through the occupiable space), the following expectations apply:Compliance when the local ventilation code governing the project is ASHRAE 62.1-2007 (or 2004 for LEED-v2 projects): We understand that many local jurisdictions would not be willing to provide confirmation that your engineered natural ventilation approach meets the intent of ASHRAE 62.1-2007. Therefore, in locations where ASHRAE 62.1-2007 is required for local ventilation code compliance, it would be sufficient to document that the plans and specifications that use the engineered natural ventilation approach have been approved by the local code authority in order to show compliance with EQ Prerequisite 1. The documentation required for EQp1 would include confirmation that all of the mandatory requirements of ASHRAE 62.1 have been met, a narrative describing the engineered ventilation modeling approach, evidence documenting that the plans have been approved by the local code authority, and some form of evidence that ASHRAE 62.1-2007 (or a later version of ASHRAE 62.1) is required for local building code compliance.Compliance when the local ventilation code governing the project can be documented to be at least as stringent as ASHRAE 62.1-2007 (or 2004 for LEED-v2 projects):If the local code requirements relative to ventilation are governed by an alternate code (any code other than ASHRAE 62.1-2007 (2004 for LEED-v2) or a later version of ASHRAE 62.1), then the project team must provide evidence that this alternate code is at least as stringent than ASHRAE 62.1-2007 (2004 for LEED-NCv2) in its entirety. If this documentation could be provided, then the approval of the local code authority would be sufficient to document compliance with the prerequisite requirements. Using this methodology, the documentation required for EQp1 would include documentation showing that the alternate code is at least as stringent than ASHRAE 62.1-2007 (2004 for LEED-v2) in its entirety, confirmation that all of the mandatory requirements of the alternate code have been met, a narrative describing the engineered ventilation modeling approach, and evidence documenting that the plans have been approved by the local code authority. Compliance when the local ventilation code governing the project cannot be documented to be at least as stringent as ASHRAE 62.1-2007: If the documentation described above cannot be provided, then, for purposes of LEED Certification, USGBC/GBCI would serve as the Authority Having Jurisdiction [since the local code authority does not have jurisdiction over ASHRAE 62.1-2007 (2004 for LEED-v2) or a ventilation standard of equivalent stringency]. In this case, the project team would be required to submit documentation showing that the intent of ASHRAE 62.1-2007 (2004 for LEED-v2) has been met with the project\'s engineered natural ventilation system. This documentation must clearly identify how the natural ventilation requirements stipulated in ASHRAE 62.1-2007 (2004 for LEED-v2) Section 5.1 have not been met (e.g. smaller operable window area, larger distance from operable windows or openings, etc.). The documentation must also clearly identify how the ventilation design has been engineered to meet the intent of ASHRAE 62.1 where the requirements of Section 5.1 have not been met. For example, if the distance from windows or openings is more than 25 feet, is there an exhaust air fan located at the furthest distance from the windows that is inducing the outdoor air to flow through the space; is that exhaust fan flow equivalent to the outside airflow that would be required for the space if the Ventilation Rate Procedure were used? If the window area is less than 4% of the floor area, is the space designed with cross-ventilation to ensure adequate airflow? Drawings and some calculations or air flow analyses will be required in addition to the narrative describing the engineered ventilation approach to justify this approach. For projects that have not yet entered the review process, it is highly recommended that this be provided in a project-specific credit interpretation request in order to achieve prior approval of the engineered natural ventilation approach rather than waiting until the system has been fully designed to pursue approval of this method.Below are some specific examples of the types of documentation that would be required if using this compliance approach; but these examples are not intended to apply to every possible engineered ventilation solution:For example, in high rise residential, the team must identify any occupiable spaces (excluding coat closets and entry vestibules) in the residential units that are more than 25 feet away from the operable windows, that are interior spaces with unobstructed free area from adjacent rooms that is less than 8% of the area of the interior room, or that have operable window openings that totals less than 4% of the total naturally ventilated floor area. A narrative and/or calculations should be provided explaining how mechanical ventilation or a combination of mechanical ventilation and natural ventilation are used to meet the ventilation requirements for those spaces. For spaces or portions of spaces that are ventilated using mechanical ventilation or a combination of mechanical and natural ventilation, the documentation must show compliance with the ventilation rates indicated in Table 6-1 of ASHRAE 62.1-2007 (2004 for LEED-v2) and the Ventilation Rate Procedure calculations indicated in Section 6.2, using appropriate values for zone air distribution effectiveness (Ez.)For high-rise residential projects attempting to show compliance for EQp1 using positively pressurized corridors that are provided with excess outdoor air [above ASHRAE 62.1-2007 (2004 for LEED-v2) minimum requirements] that is to be transferred into each living unit either via undercuts in the entry doors, transfer air grilles, or some other means, the project team must document that all mechanically ventilated spaces will meet the minimum ventilation requirements of ASHRAE 62.1-2007 (2004 for LEED-v2) Section 6.2. For projects utilizing bathroom or other exhaust to negatively pressurize the unit to draw in excess ventilation air from the corridors, if the primary makeup air source for the unit exhaust is designed to be provided through the apartment entrance/vestibule, the project team should sufficiently demonstrate that the makeup air is outdoor air and not relief air (or previously "used" outside air) from other occupied spaces in the building and that the exhaust operates continuously. Additionally, note that for the case of makeup air provided from the apartment entrance, the makeup air may substantially short-circuit the space requiring mechanical ventilation depending on the location of the air entry point and the exhaust grilles, and therefore an appropriate air distribution effectiveness (Table 6-2) must be considered (see example 6-H from the ASHRAE 62.1-2007 User\'s Manual - p. 6-20, where a zone air distribution effectiveness of 0.5 is utilized.)

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
10/1/2012
LEED Interpretation
Inquiry:

Our project is a mixed use facility with a combination of a high-rise (21-story) and mid-rise (6-story) residential apartment building. Our project utilizes all electric cooking appliances; there is no gas within the dwelling units. Table 6-4 of ASHRAE 62.1-2007 indicates 100 CFM of intermittent exhaust should be provided for residential kitchens. However, Table 6-4 also indicates that residential kitchen exhaust is Class 2 air, and ASHRAE 62.1-2007 section 5.17.3.2 indicates that Class 2 air can be re-circulated within the space. Please confirm that re-circulating kitchen hoods meet the IEQp1 prerequisite (which requires the 100 CFM of intermittent exhaust). We would also like to know if re-circulating hoods are acceptable for both mechanically ventilated and naturally ventilated apartments, since we may have both in our project. We believe re-circulated hoods should be acceptable to meet the exhaust requirements based on ASHRAE 62.1-2007 section 5.17.3.2, but wanted to confirm since this is a prerequisite.

Ruling:

The applicant is requesting confirmation that recirculating kitchen hoods meet the kitchen exhaust requirements of ASHRAE 62.1-2007 for IEQp1 in both mechanically and naturally ventilated kitchens. For mechanically ventilated kitchens, the exhaust rates listed in Table 6-4 of ASHRAE 62.1-2007 are by definition required to be discharged to outside the building (per Section 3 air, exhaust: air removed from a space and discharged to outside the building). Although recirculation of Class 2/3 air is permissible per section 5.17.3.2/5.17.3.3, the Table 6-4 exhaust requirements must still be provided (to outside the building) to meet the minimum requirements of Section 6 of ASHRAE 62.1-2007. Therefore recirculating hoods alone do not meet the exhaust requirements of Table 6-4 of the standard for mechanically ventilated kitchens. Additionally, LEED Interpretation 2208 (CIR ruling dated 6/25/2008) referenced in the inquiry, is indicated within the LEED Interpretation database as NOT applicable to the LEED NCv2009 rating system.In regards to naturally ventilated kitchens, natural ventilation systems designed in accordance with Section 5.1 of the standard do not need to meet the mechanical ventilation (exhaust) requirements of Table 6-4. Note, the exhaust requirements of Table 6-4 were clarified by ASHRAE through addendum O, which states "...exhaust requirements apply to all zones and/or systems regardless of the method used to determine minimum outdoor airflow rates (Ventilation Rate Procedure, IAQ Procedure, or Natural Ventilation Procedure)." Projects have the option to follow the ASHRAE 62.1-2007 addendum but it is not required.

Campus Applicable
No
Internationally Applicable:
No
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Requirements

Case 1. Projects able to meet the standard
OPTION 1. ASHRAE Standard 62.1-2007 or Non-U.S. Equivalent
Modify or maintain each outside air intake, supply air fan and/or ventilation distribution system to supply at least the outdoor air ventilation rate required by ASHRAE Standard 62.1–2007 ventilation rate procedure (with errata but without addenda ) under all normal operating conditions. Projects outside the U.S. may use a local equivalent to ASHRAE Standard 62.1-2007 for breathing zone minimum ventilation rates.
OPTION 2. CEN Standard EN 15251: 2007
Projects outside the U.S. may modify or maintain each outside air intake, supply air fan and/or ventilation distribution system to supply at least the outdoor air ventilation rate required by 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.
Case 2. Projects unable to meet the standard
If meeting the ventilation rates required of the above standards is infeasible because of the physical constraints of the existing ventilation system, modify or maintain the system to supply at least 10 cubic feet per minute (cfm) (5 liters per second) of outdoor air per person under all normal operating conditions. Demonstrate through design documentation, measurements or other evidence that the current system cannot provide the flow rates required by the above standards under any operating condition even when functioning properly. Each air-handling unit in the building must comply with either Case 1 or Case 2. If some airhandling units can provide the outside air flow required by the above standards and others cannot, those that can must do so. Buildings must provide at least 10 cfm (5 liters per second) per person of outside air at each air-handling unit under all normal operating conditions to earn this prerequisite.
  • Show compliance with the applicable requirement above (Case 1 or Case 2) through measurements taken at the system level (i.e., the air-handling unit). For variable air volume systems, the dampers, fan speeds, etc. must be set during the test to the worstcase system conditions (minimum outside air flow) expected during normal ventilation operations. Each air-handler must be measured; sampling or grouping of air-handlers is prohibited.
  • Implement and maintain an HVAC system maintenance program to ensure the proper operations and maintenance of HVAC components as they relate to outdoor air introduction and exhaust.
  • Test and maintain the operation of all building exhaust systems, including bathroom, shower, kitchen and parking exhaust systems.
Naturally ventilated buildings must comply with ASHRAE Standard 62.1-2007, paragraph 5.1(with errata but without addenda1). [Europe ACP: Arbeitsstaettenrichtlinie ASR 5]

Alternative Compliance Paths (ACPs)

Europe ACP: Arbeitsstaettenrichtlinie ASR 5
Projects in Europe may use Arbeitsstaettenrichtlinie ASR 5 or ASR A3.6 as a local equivalent to ASHRAE Standard 62.1-2007, paragraph 5.1.
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 information

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What if after our Preliminary Review we have to re-work 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?

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What if our systems do not meet the required outside air when systems are tested at worst-case conditions?

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Our building has a single fan that supplies outside air to multiple AHU’s. Do we need to perform outside air testing at the supply fan or at all AHUs?

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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?

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7/8/2017Updated: 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."
Campus Applicable
No
Internationally Applicable:
No
4/1/2015Updated: 4/1/2015
Regional ACP
Description of change:
Add the following after the text for Case 2:

"Projects in Europe may use Arbeitsstaettenrichtlinie ASR 5 as a local equivalent to ASHRAE Standard 62.1-2007, paragraph 5.1."
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Option 2 should read: "Projects outside the U.S. may modify or maintain each outside air intake, supply air fan and/or ventilation distribution system to supply at least the outdoor air ventilation rate required by Annex B of Comit
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Case 1 should read: "CASE 1. Projects Able to Meet Standard"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add new Option title that reads: "OPTION 1. ASHRAE Standard 62.1-2007 or Non-U.S. Equivalent"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Delete the Alternative Compliance Path for Projects Outside the U.S.
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
The first paragraph of case 2 should read: "If meeting the ventilation rates required of the above standards is infeasible because of the physical constraints of the existing ventilation system, modify or maintain the system to supply at least 10 cubic feet per minute (cfm) (5 liters per second) of outdoor air per person under all normal operating conditions. Demonstrate through design documentation, measurements or other evidence that the current system cannot provide the flow rates required by the above standards under any operating condition even when functioning properly."
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Case 2 should read: "CASE 2. Projects Unable to Meet the Standard"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
"Ventilation Rate Procedure" should be changed to "ventilation rate procedure"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Add new Option title that reads: "OPTION 2. CEN Standard EN 15251: 2007"
Campus Applicable
No
Internationally Applicable:
Yes
4/14/2010Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the text with "Breathing zone is the region within an occupied space between 3 and 6 feet above the floor. Note that this definition varies from that of ASHRAE 62.1-2007, which states that the breathing zone is between 3 inches and 6 feet from the floor, and 2 feet from the walls as well as fixed air conditioning equipment."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
In the second paragraph of case 2 replace "ASHRAE Standard 62.1-2007 (with errata but without addenda)" with "the above standards"
Campus Applicable
No
Internationally Applicable:
Yes
10/1/2014Updated: 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
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
In the second paragraph of case 2 replace "4.72" with "5"
Campus Applicable
No
Internationally Applicable:
Yes
7/6/2012Updated: 2/14/2015
Global ACP
Description of change:
Option 1 should include the original paragraph for case 1 with the following sentence at the end: "Projects outside the U.S. may use a local equivalent to ASHRAE Standard 62.1-2007 for breathing zone minimum ventilation rates."
Campus Applicable
No
Internationally Applicable:
Yes
3/25/2008
LEED Interpretation
Inquiry:

Our project is a 95,000 sf, 150 year old, Mill composed of multiple adjoining buildings. When certified, it is our understanding, that this building will be the oldest LEED certified building. The last major renovation of the building was roughly 30 years ago when we first occupied it. There have been minor renovations since then. The mechanical system is complex due to the nature of a 150 year old building and the many adaptations that happen over time. It is comprised of over 30 air-handling units. Between operable windows and the existing mechanical system 88% of the building\'s square feet meet the credit requirements for ventilation rates prescribed in ASHRAE 90.1 2004 or meet at least 10 cfm per person in areas where it is not possible to upgrade the system due to physical constraints. We have a signed contract to perform work to bring the remaining 12% of the space up to ASHRAE 90.1 2004 ventilation rates. Modifying an existing building\'s outside air distribution system to supply at least the outdoor air ventilation rates required by ASHRAE 62.1 2004 can be a lengthy process considering time to procure materials and labor. The credit implies that the system modifications and readings must be completed prior to submitting for project certification. Other prerequisites have options for plans to comply within a timeframe instead of demonstrating full compliance. LEED NC 2.2 EA PR 3 allows for a 5 year phase-out plan for CFCs in an existing facility and LEED EB 2.0 PR 3&4 allow asbestos and pcb management plans as opposed to complete removal of those substances. In regards to LEED EB 2.0 EQ PR1, we propose that if less than 25% of the building sf requires system modifications, due to the complexity of an existing building, then a plan to complete the modifications within three months will satisfy this credit. The documentation will include a signed contract by the owner and the mechanical contractor to complete the work within the three month period. Please confirm that this approach will satisfy LEEB EB 2.0 EQ PR1.

Ruling:

What you have proposed above is not acceptable to earn LEED-EBv2.0 EQp1. Outside air ventilation performance testing measurement are required for all of the existing building\'s Air Handling Units at the time of LEED-EB building certification application submittal. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
2/24/2009
LEED Interpretation
Inquiry:

We are inquiring about the approach for measuring outdoor airflow in our building to satisfy the requirements of EQp1. The building is a 47-story commercial office tower completed in 1981. It has a main air handling system to serve the office floors with a central outdoor air shaft inside the core of the building with openings at the top and bottom. Each floor has a supply air fan that draws air from the shaft and mixes it with return air. We are proposing to measure the total outdoor air intake flow for the central air shaft at the two intakes to the shaft (e.g. with a pitot tube traverse at the top and bottom), and compare this to the required CFM of outdoor air for the total square footage served as determined by the ASHRAE 62.1 calculator. EQp1 requires measurements "at the system level (i.e. the air-handling unit). each air handling unit must be measured." We propose that our outdoor air shaft is essentially a measureable system that meets the requirements. We would note that buildings with a similar supply air shaft and a central supply fan (which is a common arrangement) would be required to measure the input to the shaft; our proposed measurements should give the same level of detail about availability of outdoor air to building occupants as would be achieved in that case. While this is not essential to our proposal, it is worth noting that because of the very compact layout of the mechanical room it is very difficult to take a reasonably accurate reading of air flow on the floor-by-floor equipment-- the return air damper is immediately adjacent to the outdoor air damper, there are no straight duct runs adjacent to the supply air fan, and there is no access to the central outdoor air shaft. We believe our proposal will be more accurate than measurements on our floor fans taken with these constraints. We would also note that the building contains street-level retail spaces and a lobby that are not served by this main shaft. We would like to confirm that these spaces do not need to be measured because the lobby does not contain any regularly occupied space and the retail spaces are served by tenant owned and operated systems that the building management does not control. The retail spaces would fall under the 10% area exclusion for multi-tenant buildings explained on page 23 of the reference guide that states that all prerequisites "address base building systems or are limited to areas under management control."

Ruling:

Project teams must demonstrate that each outside air intake, supply air fan, and/or ventilation distribution system supplies the minimum OA ventilation specified by ASHRAE 62.1-2007. Based on the system description provided for this facility, measuring air intake flow for the central air shaft does not meet this requirement. Spaces under separate management, such as the retail spaces described here, may be excluded from calculations and measurements if they comprise less than 10% of the building\'s floor area. Aside from this exclusion for relatively small spaces under separate management, all occupiable spaces must be accounted for by the calculations and measurements. This includes lobby areas, which meets ASHRAE\'s definition of occupiable space: enclosed spaced intended for human activities. Only unoccupiable spaces such as equipment rooms or certain storage rooms can be excluded. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
8/1/2011
LEED Interpretation
Inquiry:

This project is a renovation of an existing building on a university campus. This building is one of a series of buildings constructed in the early 1960\'s, and the University is attempting to maintain the character and cohesiveness of the campus by preserving the existing structures and facades. Preserving the buildings also contributes to our sustainable design efforts, but it has resulted in an issue with the prerequisite for indoor air quality. The basement and first floor levels are mechanically ventilated in accordance with ASHRAE 62.1, and do not present a problem. However, running ductwork to the upper floors did prove problematic, so the design team is relying upon natural ventilation for the second and third floors. After calculating the window ventilation areas, all but three of the rooms comply with ASHRAE 62.1 for natural ventilation. The three rooms in question obtain 74%, 77% and 78% of the required ventilation area for operable windows.In order to meet University requirements and LEED Criteria all windows will be replaced with new, energy star models, to match the size and appearance of the existing windows. As previously mentioned, these new windows will generally provide 100% opening requirements, except in the three cases noted.It is the University\'s intent, as the Authority Having Jurisdiction, to grant a waiver for the minimum ventilation requirement in only these three rooms, thereby permitting the maximum use of the facility, while maintaining the historic appearance of the building.The University has therefore requested an interpretation from USGBC that this waiver for reduced ventilation requirements will be acceptable for obtaining LEED Certification for these facilities.

Ruling:

The applicant is requesting a waiver from the ASHRAE 62.1-2007 Section 5.1 natural ventilation prescriptive requirements for three rooms within the existing building. The new window areas are insufficient to meet the prescriptive requirements and are specified and installed per university requirements. ASHRAE 62.1-2007 exempts engineered natural ventilation systems when approved by the authority having jurisdiction. The natural ventilation system, as described, does not appear to be an engineered system. In this case, the prescriptive requirements could not be waived.

Campus Applicable
No
Internationally Applicable:
No
10/1/2012
LEED Interpretation
Inquiry:

We are meeting the IEQp1: Minimum Indoor Air Quality Performance with Option 2, CEN standards EN 15251:2007 and EN 13779:2007. The CEN standards provide minimum outdoor air requirements for most spaces but refer to local codes for certain specialty spaces such as parking garages. To meet the intent of the prerequisite, we propose using our local code requirements for garages, which is Teil 5 Garagen (“Section 5 – Parking Garages”) of the Verordnung über Bau und Betrieb von Sonderbauten - Nordrhein-Westfalen (“Local Law of North Rhine-Westphalia for the Construction and Operation of Specialty Buildings”), dated 17 November 2009 (SBauVO). To meet this local code, our design will use demand control ventilation with carbon monoxide (CO) detectors to limit the CO concentration. Is this approach acceptable?

Ruling:

**Update 10/01/2014: Ruling has been revised
Yes, garage demand control ventilation is an acceptable ventilation approach for parking garages. This approach is acceptable for projects pursuing Option 2 (EN 15251 and EN 13779) of EQ Prerequisite Minimum Indoor Air Quality Performance as well as the hazardous exhaust requirements in EQ Credit Indoor Chemical and Pollutant Source Control. The demand control ventilation strategy must meet the following requirements:

  • • Consider the number of cars expected to be operating in the garage at any given time and the length of time a car remains in operation in the parking garage.
  • • Consider the emission rates associated with the car exhaust for the average car.
  • • Detect the primary contaminant(s) of concern in the parking garage (for example: carbon monoxide, particulates, VOCs, NO2, etc.).
  • • Modulate airflow such that contaminant levels are maintained below a specified contaminant concentration limit and corresponding exposure period. All concentration limits must be based on local code or some other cognizant authority. If the contaminant is carbon monoxide, a concentration limit of 35 ppm time-weighted average (8 hours) and levels not to exceed 50 ppm at any time is recommended.
Campus Applicable
No
Internationally Applicable:
Yes
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
4/1/2012
LEED Interpretation
Inquiry:

Can projects use the natural ventilation prescriptive dimensional requirements written in 62.1-2010, instead of those in ASHRAE 62.1-2007? This would allow some spaces to comply with the requirements where they may otherwise not if 62.1-2007 is applied. If so, are we required to comply with the standard as a whole? Applying the standard as whole would have serious implications for new construction or existing projects attempting to comply with the Natural Ventilation Procedure because in some instances mechanical ventilation systems would have to be installed to meet the prerequisite.

Ruling:

For LEED 2009 projects where ASHRAE 62.1-2007 is the applicable standard for compliance with IEQp1, project teams may substitute the geometric requirements of ASHRAE 62.1-2010 sections 6.4.1 through 6.4.2 in place of ASHRAE 62.1-2007 section 5.1.1.
**Update October 1, 2013: This ruling also applies to EQp1 in LEED 2009 for Schools.

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 projects may use ASHRAE 62.1-2013, ASHRAE 62.1-2016 or ASHRAE 62.1-2019 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, or ASHRAE 62.1-2019 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 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.**

Campus Applicable
No
Internationally Applicable:
No
2/12/2008
LEED Interpretation
Inquiry:

Description We are planning to construct an apparel factory for LEED certification. The planned factory will have 1000 sewing machines and few finishing equipments among others. The entire space will be air conditioned to maintain ASHRAE comfort levels. The occupation density is 20-25 persons per 1000 square feet. Proposal Since there is no specified category in ASHRAE 62.1-2004 \'Ventilation for Acceptable Indoor Air Quality\' for apparel industry, we are proposing to use \'data entry\' category listed under office buildings which is similar (200W sewing machine with operator seated similar to data entry). This allows 5cfm per person with 0.06cfm per square feet. Please rule on the acceptability of this approach.

Ruling:

The CIR is asking for verification that they have selected the appropriate Occupancy Category for their project, given that it does not fall precisely within the categories listed in ASHRAE 62.1-2004. ASHRAE instructs that if the occupancy category for a proposed space or zone is not listed, the requirements for the listed occupancy category that is most similar in terms of occupant density, activities and building construction shall be used. It is up to the discretion of the design team to select the most appropriate alternative. It would be beneficial to the LEED reviewer if, included with the prerequisite submission, the applicant provides an explanation of their rationale for the selection. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
9/23/2008
LEED Interpretation
Inquiry:

There is certain language in the prerequisite description that appears to apply to a specific type of HVAC system that is not present in this building. Specifically, the language stating that each "air handling unit in the building must comply with either Option A or Option B" assumes that all buildings have air handling units. This building does not have air handling units. The design is that of approximately 150 heat pumps with individual zone temperature control and ducted outside air through a single make-up air handling unit located on the roof. On each floor there is a takeoff from the main outside air riser with a ducted outside air distribution loop that delivers outside air to each heat pump. Verifying the outside airflow at each heat pump, as if each heat pump is an independent air handling unit, is cost prohibitive and places our LEED application at an undue disadvantage in comparison with a building with contemporary variable air volume (VAV) air handling units or other zone level control. Furthermore, the use of the terminology of air handling unit being the primary source of outside air is in conflict with the description under option A that provides for verification of "each outside air intake, supply air fan AND/OR ventilation distribution system to supply at least the outdoor air ventilation rate required by ASHRAE 62.1-2007." We believe that the terminology that is applicable in the design of the HVAC systems at these buildings is more consistent with Option A verification requirements, i.e., ventilation distribution system. Furthermore, the requirement for verification of outside air ventilation at each "air handling unit" would not apply since it represents an inconsistent requirement for buildings with heat pumps versus a building with floor level air handling units and zone level terminal VAVs. We request that the following scope of services be considered an acceptable procedure for outside air verification and satisfaction EQ Prerequisite 1. 1. Perform duct traverses at the takeoffs from the main outside air makeup unit supply riser. The traverse shall provide data on the outside air velocity pressure and airflow (CFM) for the ducted "ventilation distribution system" that delivers outside air to the terminal heat pumps. These measurements shall be performed on every floor ventilation air distribution system (9 floors per building). These measurements shall be performed with the 400 Brand make-up air VFD at 60 Hz at its normal operating condition (unit is constant speed without VFD). This approach will provide for 100% of the building outside air delivery on a floor by floor basis. It is believed that this approach is comparable to measuring outside air at a single air handler in a system design where each floor is served by a single air handler. 2. Perform airflow measurements at the main make-up air unit on the roof of building. The VFD shall be set at 60 Hz for the preliminary measurement. These measurements shall be displayed in a final report in a comparative manner with the summation of the individual floor level ventilation air distribution systems. 3. Perform pressure measurements across the fan and across various turns and obstructions prior to the building riser. The VFD shall be set at 60 Hz for the preliminary measurement. 4. Provide measurements of the exhaust air from the ducting for each of the restroom exhaust ducts on each of the 9 floors. 5. Perform airflow measurements at the main exhaust air unit on the roof. The VFDs shall be set at the typical operating speed and at 60 Hz. At both settings, on each of the exhaust fans, conduct airflow and pressure measurements.

Ruling:

The measurement approach explained in steps 1-3 above, based on the information provided for the system under consideration, appears appropriate for demonstrating the OA volume to the project building. In general, project teams should develop a measurement protocol suited to the air handling and distribution system that is in accordance with SMACNA\'s HVAC Systems - Testing, Adjusting and Balancing, or equivalent at least to the extent necessary to verify conformations with the total outdoor air flow and space supply air flow requirements of ASHRAE 62.1. Please note that Ventilation Rate Procedure calculations should factor in zone ventilation efficiency (Evz), as appropriate. This factor modifies the required outdoor air based on the efficiency with which a system distributes outdoor air from the intake to an individual breathing zone (in the case the zone served by each heat pump). Steps 4-5 describe a procedure for testing exhaust systems. Exhaust system steps should confirm proper exhaust function, such as fan speed, voltage, control sequences, and set points as applicable. Airflow measurements is one option for demonstrating proper function, though there may be simpler testing options available to the project team.

Campus Applicable
No
Internationally Applicable:
No
11/11/2008
LEED Interpretation
Inquiry:

The project building contains 40 AHUs which are each monitored and regulated based on CO2 differential rather than outdoor air introduction. In lieu of documenting a measurement of outdoor airflow at each AHU, the project team proposes to show compliance with the outdoor air ventilation rate required by ASHRAE 62.1-2007 by documenting the differential between the CO2 level in each AHU\'s return duct and the CO2 level in the outdoor environment. The correlation between the differential CO2 readings and the ventilation rate per person is described in Appendix C of the ASHRAE 62.1-2007 standard while Section 6.2.7 of ASHRAE 62.1-2007 supports the project team\'s use of CO2 differential to maintain an average ventilation rate per occupant in each zone. The project building utilizes a demand ventilation control sequence which was adapted to an existing outdoor air delivery system with motorized dampers that adjust the volume of outside air that is delivered to each zone. Damper adjustment is based on the differential between the CO2 levels in the return air duct and the CO2 levels in the outdoor environment. The control sequence utilizes a PID loop to help anticipate the volume of air required rather than try to catch up as the levels of CO2 increase on the floor.

Ruling:

Because the Ventilation Rate Procedure stipulates outdoor air levels adequate to address both bioeffluents from the building\'s populations and air contaminants off-gassing from the building itself, showing that CO2 concentrations are held within a certain level relative to outdoor CO2 levels per Appendix C of the standard is not sufficient for demonstrating compliance with the standard in an existing building. The above approach addresses only the occupancy-related ventilation requirements. To show compliance with the requirements, assessment of the total volume of outdoor air delivered to each ventilation zone is required. Applicable Internationally.

Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011
LEED Interpretation
Inquiry:

How do naturally ventilated projects, such as high rise residential projects, that do not qualify with the requirements of the Ventilation Rate Procedure, or ASHRAE 62.1 Section 5.1, or CIBSE Applications Manual 10 meet IEQp1 for v2 and 2009 rating systems?

Ruling:

For projects that do not qualify with the requirements of the Ventilation Rate Procedure, or ASHRAE 62.1 Section 5.1, or CIBSE Applications Manual 10, and are pursuing an engineered ventilation system (e.g. a combination of natural ventilation with mechanical exhaust, or some other means of assisting the outside airflow through the openings and circulating it through the occupiable space), the following expectations apply:Compliance when the local ventilation code governing the project is ASHRAE 62.1-2007 (or 2004 for LEED-v2 projects): We understand that many local jurisdictions would not be willing to provide confirmation that your engineered natural ventilation approach meets the intent of ASHRAE 62.1-2007. Therefore, in locations where ASHRAE 62.1-2007 is required for local ventilation code compliance, it would be sufficient to document that the plans and specifications that use the engineered natural ventilation approach have been approved by the local code authority in order to show compliance with EQ Prerequisite 1. The documentation required for EQp1 would include confirmation that all of the mandatory requirements of ASHRAE 62.1 have been met, a narrative describing the engineered ventilation modeling approach, evidence documenting that the plans have been approved by the local code authority, and some form of evidence that ASHRAE 62.1-2007 (or a later version of ASHRAE 62.1) is required for local building code compliance.Compliance when the local ventilation code governing the project can be documented to be at least as stringent as ASHRAE 62.1-2007 (or 2004 for LEED-v2 projects):If the local code requirements relative to ventilation are governed by an alternate code (any code other than ASHRAE 62.1-2007 (2004 for LEED-v2) or a later version of ASHRAE 62.1), then the project team must provide evidence that this alternate code is at least as stringent than ASHRAE 62.1-2007 (2004 for LEED-NCv2) in its entirety. If this documentation could be provided, then the approval of the local code authority would be sufficient to document compliance with the prerequisite requirements. Using this methodology, the documentation required for EQp1 would include documentation showing that the alternate code is at least as stringent than ASHRAE 62.1-2007 (2004 for LEED-v2) in its entirety, confirmation that all of the mandatory requirements of the alternate code have been met, a narrative describing the engineered ventilation modeling approach, and evidence documenting that the plans have been approved by the local code authority. Compliance when the local ventilation code governing the project cannot be documented to be at least as stringent as ASHRAE 62.1-2007: If the documentation described above cannot be provided, then, for purposes of LEED Certification, USGBC/GBCI would serve as the Authority Having Jurisdiction [since the local code authority does not have jurisdiction over ASHRAE 62.1-2007 (2004 for LEED-v2) or a ventilation standard of equivalent stringency]. In this case, the project team would be required to submit documentation showing that the intent of ASHRAE 62.1-2007 (2004 for LEED-v2) has been met with the project\'s engineered natural ventilation system. This documentation must clearly identify how the natural ventilation requirements stipulated in ASHRAE 62.1-2007 (2004 for LEED-v2) Section 5.1 have not been met (e.g. smaller operable window area, larger distance from operable windows or openings, etc.). The documentation must also clearly identify how the ventilation design has been engineered to meet the intent of ASHRAE 62.1 where the requirements of Section 5.1 have not been met. For example, if the distance from windows or openings is more than 25 feet, is there an exhaust air fan located at the furthest distance from the windows that is inducing the outdoor air to flow through the space; is that exhaust fan flow equivalent to the outside airflow that would be required for the space if the Ventilation Rate Procedure were used? If the window area is less than 4% of the floor area, is the space designed with cross-ventilation to ensure adequate airflow? Drawings and some calculations or air flow analyses will be required in addition to the narrative describing the engineered ventilation approach to justify this approach. For projects that have not yet entered the review process, it is highly recommended that this be provided in a project-specific credit interpretation request in order to achieve prior approval of the engineered natural ventilation approach rather than waiting until the system has been fully designed to pursue approval of this method.Below are some specific examples of the types of documentation that would be required if using this compliance approach; but these examples are not intended to apply to every possible engineered ventilation solution:For example, in high rise residential, the team must identify any occupiable spaces (excluding coat closets and entry vestibules) in the residential units that are more than 25 feet away from the operable windows, that are interior spaces with unobstructed free area from adjacent rooms that is less than 8% of the area of the interior room, or that have operable window openings that totals less than 4% of the total naturally ventilated floor area. A narrative and/or calculations should be provided explaining how mechanical ventilation or a combination of mechanical ventilation and natural ventilation are used to meet the ventilation requirements for those spaces. For spaces or portions of spaces that are ventilated using mechanical ventilation or a combination of mechanical and natural ventilation, the documentation must show compliance with the ventilation rates indicated in Table 6-1 of ASHRAE 62.1-2007 (2004 for LEED-v2) and the Ventilation Rate Procedure calculations indicated in Section 6.2, using appropriate values for zone air distribution effectiveness (Ez.)For high-rise residential projects attempting to show compliance for EQp1 using positively pressurized corridors that are provided with excess outdoor air [above ASHRAE 62.1-2007 (2004 for LEED-v2) minimum requirements] that is to be transferred into each living unit either via undercuts in the entry doors, transfer air grilles, or some other means, the project team must document that all mechanically ventilated spaces will meet the minimum ventilation requirements of ASHRAE 62.1-2007 (2004 for LEED-v2) Section 6.2. For projects utilizing bathroom or other exhaust to negatively pressurize the unit to draw in excess ventilation air from the corridors, if the primary makeup air source for the unit exhaust is designed to be provided through the apartment entrance/vestibule, the project team should sufficiently demonstrate that the makeup air is outdoor air and not relief air (or previously "used" outside air) from other occupied spaces in the building and that the exhaust operates continuously. Additionally, note that for the case of makeup air provided from the apartment entrance, the makeup air may substantially short-circuit the space requiring mechanical ventilation depending on the location of the air entry point and the exhaust grilles, and therefore an appropriate air distribution effectiveness (Table 6-2) must be considered (see example 6-H from the ASHRAE 62.1-2007 User\'s Manual - p. 6-20, where a zone air distribution effectiveness of 0.5 is utilized.)

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
10/1/2012
LEED Interpretation
Inquiry:

Our project is a mixed use facility with a combination of a high-rise (21-story) and mid-rise (6-story) residential apartment building. Our project utilizes all electric cooking appliances; there is no gas within the dwelling units. Table 6-4 of ASHRAE 62.1-2007 indicates 100 CFM of intermittent exhaust should be provided for residential kitchens. However, Table 6-4 also indicates that residential kitchen exhaust is Class 2 air, and ASHRAE 62.1-2007 section 5.17.3.2 indicates that Class 2 air can be re-circulated within the space. Please confirm that re-circulating kitchen hoods meet the IEQp1 prerequisite (which requires the 100 CFM of intermittent exhaust). We would also like to know if re-circulating hoods are acceptable for both mechanically ventilated and naturally ventilated apartments, since we may have both in our project. We believe re-circulated hoods should be acceptable to meet the exhaust requirements based on ASHRAE 62.1-2007 section 5.17.3.2, but wanted to confirm since this is a prerequisite.

Ruling:

The applicant is requesting confirmation that recirculating kitchen hoods meet the kitchen exhaust requirements of ASHRAE 62.1-2007 for IEQp1 in both mechanically and naturally ventilated kitchens. For mechanically ventilated kitchens, the exhaust rates listed in Table 6-4 of ASHRAE 62.1-2007 are by definition required to be discharged to outside the building (per Section 3 air, exhaust: air removed from a space and discharged to outside the building). Although recirculation of Class 2/3 air is permissible per section 5.17.3.2/5.17.3.3, the Table 6-4 exhaust requirements must still be provided (to outside the building) to meet the minimum requirements of Section 6 of ASHRAE 62.1-2007. Therefore recirculating hoods alone do not meet the exhaust requirements of Table 6-4 of the standard for mechanically ventilated kitchens. Additionally, LEED Interpretation 2208 (CIR ruling dated 6/25/2008) referenced in the inquiry, is indicated within the LEED Interpretation database as NOT applicable to the LEED NCv2009 rating system.In regards to naturally ventilated kitchens, natural ventilation systems designed in accordance with Section 5.1 of the standard do not need to meet the mechanical ventilation (exhaust) requirements of Table 6-4. Note, the exhaust requirements of Table 6-4 were clarified by ASHRAE through addendum O, which states "...exhaust requirements apply to all zones and/or systems regardless of the method used to determine minimum outdoor airflow rates (Ventilation Rate Procedure, IAQ Procedure, or Natural Ventilation Procedure)." Projects have the option to follow the ASHRAE 62.1-2007 addendum but it is not required.

Campus Applicable
No
Internationally Applicable:
No

LEEDuser expert

Andrew Mitchell, P.E.

Mitchell Gulledge Engineering, Inc.
Principal

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