Remove Footnote, "CO2 monitoring is required in densely occupied spaces, in addition to outdoor air intake flow measurement."
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Credit achievement rate
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Dylan Connelly
Integral Group
Mechanical Engineer
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Credit language
© Copyright U.S. Green Building Council, Inc. All rights reserved.
Requirements
Install permanent monitoring systems to ensure that ventilation systems maintain design minimum requirements. Configure all monitoring equipment to generate an alarm when the airflow values or carbon dioxide (CO2) levels vary by 10% or more from the design values via either a building automation system alarm to the building operator or a visual or audible alert to the building occupants.
AND
Case 1. Mechanically ventilated spaces
Monitor CO2 concentrations within all densely occupied spaces i.e., those with a design occupant density of 25 people or more per 1,000 square feet (95 square meters). CO2 monitors must be between 3 and 6 feet (between 1 and 2 meters) above the floor. Provide a direct outdoor airflow measurement device capable of measuring the minimum outdoor air intake flow with an accuracy of plus or minus 15% of the design minimum outdoor air rate, based on the value determined in IEQ Prerequisite 1: Minimum Indoor Air Quality Performance, for mechanical ventilation systems where 20% or more of the design supply airflow serves non-densely occupied spaces.Case 2. Naturally ventilated spaces
Monitor CO2 concentrations within all naturally ventilated spaces. CO2 monitors must be between 3 and 6 feet feet (between 1 and 2 meters) above the floor. One CO2 sensor may be used to monitor multiple nondensely occupied spaces if the natural ventilation design uses passive stack(s) or other means to induce airflow through those spaces equally and simultaneously without intervention by building occupants. See all forum discussions about this credit »What does it cost?
Cost estimates for this credit
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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
If my project is using air handlers that supply 100% outside air at a constant volume, do I still need to install an airflow monitoring device?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
5/9/2011 – Updated: 6/18/2015
Reference Guide Correction
Description of change:
Campus Applicable
No
Internationally Applicable:
No
5/9/2011 – Updated: 6/18/2015
Rating System Correction
Description of change:
Remove Footnote, "CO2 monitoring is required in densely occupied spaces, in addition to outdoor air intake flow measurement."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Rating System Correction
Description of change:
Re-number the footnotes so they become the following:? CO2 monitoring is required in densely occupied spaces, in addition tooutdoor air intake flow measurement.? Project teams wishing to use ASHRAE approved addenda for thepurposes of this credit may do so at their discretion. Addenda must beapplied consistently across all LEED credits.
Campus Applicable
No
Internationally Applicable:
No
4/14/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the text with "Breathing zone is the region within an occupiedspace between 3 and 6 feet above the floor. Note that this definitionvaries from that of ASHRAE 62.1-2007, which states that the breathingzone is between 3 inches and 6 feet from the floor, and 2 feet from thewalls as well as fixed air conditioning equipment."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Rating System Correction
Description of change:
Update the footnote references in the section so the text becomes the following:Monitor CO2 concentrations within all densely occupied spaces (those witha design occupant density of 25 people or more per 1,000 square feet).CO2 monitors must be between 3 and 6 feet above the floor.?Provide a direct outdoor airflow measurement device capable of measuringthe minimum outdoor air intake flow with an accuracy of plus or minus 15%of the design minimum outdoor air rate, as defined by ASHRAE 62.1-2007(with errata but without addenda?) for mechanical ventilation systemswhere 20% or more of the design supply airflow serves nondenselyoccupied spaces.
Campus Applicable
No
Internationally Applicable:
No
11/1/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for nonoccupied spaces, "Nonoccupied spaces are defined as spaces designed for equipment and machinery or storage with no human occupancy except for maintenance, repairs, and equipment retrieval."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012 – Updated: 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
11/1/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for non-densely occupied space, "Non-densely occupied spaces are areas with a design occupant density of less than 25 people per 1,000 square feet (40 square feet or more per person)."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Re-number the footnotes so they become the following:? CO2 monitoring is required in densely occupied spaces, in addition tooutdoor air intake flow measurement.? Project teams wishing to use ASHRAE approved addenda for thepurposes of this credit may do so at their discretion. Addenda must beapplied consistently across all LEED credits.
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Update the footnote references in the section so the text becomes the following:Monitor CO2 concentrations within all densely occupied spaces (those witha design occupant density of 25 people or more per 1,000 square feet).CO2 monitors must be between 3 and 6 feet above the floor.?Provide a direct outdoor airflow measurement device capable of measuringthe minimum outdoor air intake flow with an accuracy of plus or minus 15%of the design minimum outdoor air rate, as defined by ASHRAE 62.1-2007(with errata but without addenda?) for mechanical ventilation systemswhere 20% or more of the design supply airflow serves nondenselyoccupied spaces.
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Rating System Correction
Description of change:
At the end of the paragraph, remove the footnote "?"
Campus Applicable
No
Internationally Applicable:
No
11/3/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the last two sentences of the paragraph with the following text:To satisfy the requirements of this credit, the measurement device mustbe capable of measuring the minimum outdoor air intake flow with anaccuracy of plus or minus 15% when the system is providing the designminimum outdoor air rate. When the measurement device generates ameasurement of outdoor air intake flow that is more than 10% below thedesign outdoor air minimum values, the monitoring system should beconfigured to deliver a visible or audible alert to the system operator toindicate that operational adjustments may be necessary.
Campus Applicable
No
Internationally Applicable:
No
11/1/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Revise the definition for densely occupied spaces to be, "Densely occupied spaces are areas with a design occupant density of 25 people or more per 1,000 square feet (40 square feet or less per person)."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
In the second paragraph of Case 1, replace "as defined by ASHRAE 62.1-2007 (with errata but without addenda )" with "based on the value determined in IEQ Prerequisite 1: Minimum Indoor Air Quality Performance,"
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for occupied spaces, "Occupied Spaces are defined as enclosed spaces that can accommodate human activities. Occupied spaces are further classified as regularly occupied or non-regularly occupied spaces based on the duration of the occupancy, individual or multi-occupant based on the quantity of occupants, and densely or non-densely occupied spaces based upon the concentration of occupants in the space."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
At the end of the paragraph, remove the footnote "?"
Campus Applicable
No
Internationally Applicable:
No
1/16/2007
LEED Interpretation
Inquiry:
Residential projects without directly ducted makeup air typically get makeup air either from operable windows alone, from operable windows plus pressurized corridors, or from either or both of those sources, plus negative pressure created by bathroom fans and kitchen exhaust hoods (which may or may not be always on). For LEED NC 2.1 projects, it was asked whether CO2 monitors must be provided for low density residences. In the CIR ruling from 9/20/2004, it was confirmed that CO2 monitors for these residential spaces are not necessary to meet the intent of the credit. For LEED NC 2.2 projects, does this ruling from 9/20/2004 apply? Do residential units without ducted makeup air now require CO2 monitoring? If the ruling varies depending on the strategy by which the units receive makeup air (operable windows, pressurized corridors, bathroom and kitchen fans alone or in combination), can you indicate which scenarios require CO2 monitoring and which do not?
Ruling:
The applicant is requesting clarification on the applicability of a LEED NC 2.1 CIR ruling for LEED-NC 2.2. Under LEED-NC v2.2, EQc1 has been modified to include two methods of compliance: 1. For densely occupied areas (25 persons/ 1000 SF) use CO2 monitoring 2. For systems serving all other spaces employ outdoor air delivery monitoring Based on the information provided in this inquiry, the first option described above does not apply to individual residential units. Therefore, the second option should be followed. If the outside air (OA) supply is through a pressurized corridor, the implementation of this credit is straight forward. If OA is introduced directly to a conditioning unit (for example- a heat pump or a fan-coil unit) it may be possible to monitor OA delivery to the unit individually. For all other modes of OA supply, this credit may not be applicable. If the residential project has any densely occupied spaces such as meeting rooms, CO2 monitoring should be provided for those specific spaces.
Campus Applicable
No
Internationally Applicable:
No
8/13/2007
LEED Interpretation
Inquiry:
To monitor outside air intake we propose to utilize the DDC controls to measure temperatures for the outside air, return air, mixed air, and supply air. The DDC calculations will result in the total CFM of outside air delivered well within the 15% accuracy required. Additionally, the controls configuration will provide alarms whenever the delivered amount of outside air is below the minimum threshold. As a secondary measure, CO2 sensors will be required for ALL building tenants per the LEED CI credit EQ 1. This project exceeds the minimum ventilation requirements of ASHRAE Standard 62.1-2004 by well over 30%. These three parameters will ensure that the minimum outside air will be delivered, monitored, and alarmed per the requirements of LEED CS EQ credit 1. Will our proposal meet the intent of this credit?
Ruling:
The applicant is proposing an alternative outside air delivering monitoring device which monitors temperatures of outside air. The EQc1 credit requirement states for mechanically ventilated spaces: "For each mechanical ventilation system, provide a direct outdoor airflow measurement device capable of measuring the minimum outdoor airflow rate with an accuracy of plus or minus 15% of the design minimum outdoor air rate, as defined by ASHRAE 62.1-2004." The system proposed does not directly measure outdoor airflow rates, as flow rate cannot be measured by temperatures; therefore this strategy would not meet the credit requirements. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
7/2/2008
LEED Interpretation
Inquiry:
A roof-mounted fan delivers 100% outdoor air into a dedicated shaft duct. The fan operates using a variable frequency drive motor to maintain a constant static pressure within the shaft duct. A variable-air-volume (VAV) terminal unit located in the mechanical room on each floor of the building controls the delivery of the outdoor air from this shaft duct to the mechanical room. This VAV terminal unit is ducted on its intake side to the dedicated outdoor air shaft duct. Only outdoor air passes through this VAV terminal unit. The mechanical room acts as a mixing plenum for the outdoor air and the return air from the floor before that mixed air is drawn into the air handling unit located in the mechanical room. The air handling system is a floor-by-floor design with a single air handling unit located on each floor and serving only that floor. This VAV terminal unit contains a pressure independent primary air volume controller that controls the supply air quantity to within 5% of the airflow setpoint regardless of changes in system static pressure. This VAV terminal unit measures airflow with a pitot-tube assembly. The independent controller converts the measured velocity pressure using the known cross-sectional area to calculate the actual airflow rate. This measurement and calculation is within 5% of the airflow rate setpoint. In the "occupied" mode, each VAV terminal unit controls to the design outdoor air flow setpoint for its respective air handling system. In the "unoccupied" mode, the control damper in each VAV terminal unit is closed. The VAV terminal units controlling outdoor air to each air handling system operate based on the following sequence of operation for the control, monitoring and alarming of the outdoor airflow provided to each floor\'s air handling system: - Outdoor air fan energizes when the Energy Management System (EMS) indicates the building is in "occupied" mode. - Each VAV terminal unit in the outdoor air delivery system opens upon energizing of the outdoor air fan. - A temperature sensor at each VAV terminal unit controls the electric heater to maintain a minimum of 50 degrees F in the mechanical room. - A VAV terminal unit fails closed in the event of power loss. - The VAV terminal unit controller shall monitor and trend the outdoor air delivered to each air handling system. - Each VAV terminal unit graphic displays the measured airflow and the airflow setpoint. - If the measured airflow at a VAV terminal unit varies by more than 10% of its setpoint, an alarm message is sent to the Central Control Panel (CCP) and a notification alarm is generated to alert the building operator of this condition. With respect to carbon dioxide (CO2) monitoring, a CO2 sensor is located in the return air transfer duct at each floor\'s mechanical room. This sensor has an accuracy of +/-3% over a range of 0-2000 ppm. Each floor\'s CO2 sensor is monitored and trended by the EMS. The EMS has no less than fifty (50) points available for future tenant use as inputs for CO2 sensors installed in densely occupied areas. Does the system as outlined herein meet the requirements of LEED-CS v2 EQ Credit 1 - Outdoor Air Delivery Monitoring?
Ruling:
The approach described above will satisfy the requirements of this credit. However, the project team should make sure that the VAV setpoint is established based on the minimum outdoor air requirements of ASHRAE Standard 62.1-2004, for each floor to comply with EQp1. Additionally, the roof-mounted fan which is stated to be maintaining static pressure in the shaft duct, should provide at least the minimum outdoor air requirement of ASHRAE Standard 62.1-2004, for the building to comply with EQp1. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
3/27/2007
LEED Interpretation
Inquiry:
Our facility\'s HVAC system consists of high-efficiency, packaged, direct-fired \'Cambridge\' Unit heaters, passive intake louvers and powered exhaust fans. There is no ducted air distribution system. We propose to install airflow devices at each of the exhaust fans, instead of the intakes. We feel that this makes sense because the exhaust fans will always be \'on\', whereas the \'Cambridge\' Unit heaters will not, when heat is not required. Furthermore, it follows that measuring air being discharged from the building would be equivalent to measuring fresh air being induced into the building, since fresh air will necessarily replace exhaust air in an equal amount. Considering that this building type can be somewhat porous (when the loading dock doors are open) and, per industry norms, always under negative pressurization, it is most logical to measure air where it is being exhausted (since this necessarily will happen in a controlled way at specific locations), rather than where it is being brought in (which would be variable and would happen throughout the building). In accordance with the requirements of this credit, the airflow metering devices will be tied to alarms to alert building occupants if the prescribed airflow pattern ever fails. Finally, the minimum outside air rate (OAR) will be considerably higher than the minimum prescribed by ASHRAE 62.1-2004. The standard prescribes a minimum OAR of 0.06 cfm/sf for this building type. The specified design OAR of 3 complete air changes per 8 hour interval exceeds this minimum by a factor of 3.66. This will also allow us to achieve EQc2 - Increased Ventilation. Is this allowed?
Ruling:
The applicant is requesting an interpretation of EQc1 and proposing to monitor exhaust air-flow rather than incoming air flow. Based on the project description and conditions, it appears that this credit is not applicable. The credit is specifically intended to address issues with ventilation in environments where a fixed amount of minimum outside air is provided through a specific incoming path. Since the path of incoming air in this project can vary significantly, it would be nearly impossible to trouble-shoot any problems in the ventilation system through the proposed monitoring system. Based on the project narrative, it appears that this project would be best served by a CO2/ CO monitoring system that has alarm triggers.
Campus Applicable
No
Internationally Applicable:
No
4/24/2008
LEED Interpretation
Inquiry:
Our office has two projects that have been struggling with the requirements of EQ Credit 1. Although very different in type, they have taken similar approaches to ensuring outdoor air delivery to occupants. 1) The first project is a historic renovation of a low-rise residential building with seven units. Fresh air is delivered to the building via an Energy Recovery Unit (ERU) that exchanges exhaust air from the kitchens and washrooms of the units for 100% outside air, which is delivered to fan powered boxes in each unit. The ERU does not have an economizer or an air damper. 2) The second is the renovation of an existing doubled loaded corridor school building, which does not have a central air conditioning system, but instead uses perimeter unit ventilators to provide and heat outside air. The dampers on these units are controlled by CO2 sensors located at the thermostat, and will meet the intent of the credit. However, a few non-perimeter classrooms and offices cannot accommodate these perimeter unit ventilators, and thus has a centrally located unit ventilator that provides fresh air to these particular rooms. This ventilator also uses 100% outside air, and also has no dampers. Our suggested approach to both of these projects is to use a current transducer to monitor the performance and status of the ERU and unit ventilators, instead of using an airflow monitor as the credit requirements call for. The current of the fan varies proportionally to the load so that if the unit is malfunctioning (decreased or no airflow) it will be clearly indicated by the power being consumed by the fan. The CT monitor would then report immediately to building management who would field verify the problem and determine if maintenance is needed. We feel this approach complies with the intent of this credit for the following reasons: 1. The units are designed to run at a fixed airflow rate at all times, never to be affected by damper positions, and thus the only instance where air is not being delivered at the appropriate flow is if there is a malfunction with the unit. 2. Monitoring the outdoor airflow of units that are equipped with outdoor air dampers is useful because the dampers can be adjusted based on outdoor airflow readings. Our systems, however, do not have an outdoor air damper because they use only outdoor air. If we directly measure the outdoor airflow, the unit has no way to respond or be recalibrated to address excess CO2 in the space. Outdoor air flow monitoring could be performed, but the results would be of little use. 100% outside air systems are an important tool in providing fresh and healthy interior environments. We believe that the CT monitoring approach is the best method by which 100% outdoor air units can be measured, and also addresses the intent underlying tenets of the credit. It can be argued that outdoor airflow monitors could also provide this level of measurement (on or off), but it provides no more value or functionality than the CT monitor suggested here in the case of 100% outside air units. Please comment on whether this strategy can be used in achieving EQ credit 1.
Ruling:
The CIR is asking if current transducer (CT) monitors are adequate devices to monitor outside air delivery. For a constant volume 100% outside air system similar to the one described by the proponent, the CT approach may satisfy the credit requirement for a direct outdoor airflow measurement device, provided the CT device has been properly calibrated during the installation and commissioning process. Properly calibrated, the CT device would alert the BAS to a change in the fan status, which would indicate a change to the amount of outside air being delivered. In order to satisfy the credit requirements the submittal must show how the CT has been calibrated, and must outline the monitoring sequence. If the system is not 100% outside air, or not constant volume, the CT device would not be adequate. Note that the CT device does not relieve the project of the requirement to monitor room CO2 levels in all densely occupied spaces. -NCv2.2 Requirements state clearly that densely occupied spaces (such as classrooms - mentioned in the CIR) must have CO2 concentrations monitored. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
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© Copyright U.S. Green Building Council, Inc. All rights reserved.
Requirements
Install permanent monitoring systems to ensure that ventilation systems maintain design minimum requirements. Configure all monitoring equipment to generate an alarm when the airflow values or carbon dioxide (CO2) levels vary by 10% or more from the design values via either a building automation system alarm to the building operator or a visual or audible alert to the building occupants.
AND
Case 1. Mechanically ventilated spaces
Monitor CO2 concentrations within all densely occupied spaces i.e., those with a design occupant density of 25 people or more per 1,000 square feet (95 square meters). CO2 monitors must be between 3 and 6 feet (between 1 and 2 meters) above the floor. Provide a direct outdoor airflow measurement device capable of measuring the minimum outdoor air intake flow with an accuracy of plus or minus 15% of the design minimum outdoor air rate, based on the value determined in IEQ Prerequisite 1: Minimum Indoor Air Quality Performance, for mechanical ventilation systems where 20% or more of the design supply airflow serves non-densely occupied spaces.Case 2. Naturally ventilated spaces
Monitor CO2 concentrations within all naturally ventilated spaces. CO2 monitors must be between 3 and 6 feet feet (between 1 and 2 meters) above the floor. One CO2 sensor may be used to monitor multiple nondensely occupied spaces if the natural ventilation design uses passive stack(s) or other means to induce airflow through those spaces equally and simultaneously without intervention by building occupants.XX%
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If my project is using air handlers that supply 100% outside air at a constant volume, do I still need to install an airflow monitoring device?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.) |
5/9/2011 – Updated: 6/18/2015
Reference Guide Correction
Description of change:
Remove Footnote, "CO2 monitoring is required in densely occupied spaces, in addition to outdoor air intake flow measurement."
Campus Applicable
No
Internationally Applicable:
No
5/9/2011 – Updated: 6/18/2015
Rating System Correction
Description of change:
Remove Footnote, "CO2 monitoring is required in densely occupied spaces, in addition to outdoor air intake flow measurement."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Rating System Correction
Description of change:
Re-number the footnotes so they become the following:? CO2 monitoring is required in densely occupied spaces, in addition tooutdoor air intake flow measurement.? Project teams wishing to use ASHRAE approved addenda for thepurposes of this credit may do so at their discretion. Addenda must beapplied consistently across all LEED credits.
Campus Applicable
No
Internationally Applicable:
No
4/14/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the text with "Breathing zone is the region within an occupiedspace between 3 and 6 feet above the floor. Note that this definitionvaries from that of ASHRAE 62.1-2007, which states that the breathingzone is between 3 inches and 6 feet from the floor, and 2 feet from thewalls as well as fixed air conditioning equipment."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Rating System Correction
Description of change:
Update the footnote references in the section so the text becomes the following:Monitor CO2 concentrations within all densely occupied spaces (those witha design occupant density of 25 people or more per 1,000 square feet).CO2 monitors must be between 3 and 6 feet above the floor.?Provide a direct outdoor airflow measurement device capable of measuringthe minimum outdoor air intake flow with an accuracy of plus or minus 15%of the design minimum outdoor air rate, as defined by ASHRAE 62.1-2007(with errata but without addenda?) for mechanical ventilation systemswhere 20% or more of the design supply airflow serves nondenselyoccupied spaces.
Campus Applicable
No
Internationally Applicable:
No
11/1/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for nonoccupied spaces, "Nonoccupied spaces are defined as spaces designed for equipment and machinery or storage with no human occupancy except for maintenance, repairs, and equipment retrieval."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012 – Updated: 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
11/1/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for non-densely occupied space, "Non-densely occupied spaces are areas with a design occupant density of less than 25 people per 1,000 square feet (40 square feet or more per person)."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Re-number the footnotes so they become the following:? CO2 monitoring is required in densely occupied spaces, in addition tooutdoor air intake flow measurement.? Project teams wishing to use ASHRAE approved addenda for thepurposes of this credit may do so at their discretion. Addenda must beapplied consistently across all LEED credits.
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Update the footnote references in the section so the text becomes the following:Monitor CO2 concentrations within all densely occupied spaces (those witha design occupant density of 25 people or more per 1,000 square feet).CO2 monitors must be between 3 and 6 feet above the floor.?Provide a direct outdoor airflow measurement device capable of measuringthe minimum outdoor air intake flow with an accuracy of plus or minus 15%of the design minimum outdoor air rate, as defined by ASHRAE 62.1-2007(with errata but without addenda?) for mechanical ventilation systemswhere 20% or more of the design supply airflow serves nondenselyoccupied spaces.
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Rating System Correction
Description of change:
At the end of the paragraph, remove the footnote "?"
Campus Applicable
No
Internationally Applicable:
No
11/3/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the last two sentences of the paragraph with the following text:To satisfy the requirements of this credit, the measurement device mustbe capable of measuring the minimum outdoor air intake flow with anaccuracy of plus or minus 15% when the system is providing the designminimum outdoor air rate. When the measurement device generates ameasurement of outdoor air intake flow that is more than 10% below thedesign outdoor air minimum values, the monitoring system should beconfigured to deliver a visible or audible alert to the system operator toindicate that operational adjustments may be necessary.
Campus Applicable
No
Internationally Applicable:
No
11/1/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Revise the definition for densely occupied spaces to be, "Densely occupied spaces are areas with a design occupant density of 25 people or more per 1,000 square feet (40 square feet or less per person)."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
In the second paragraph of Case 1, replace "as defined by ASHRAE 62.1-2007 (with errata but without addenda )" with "based on the value determined in IEQ Prerequisite 1: Minimum Indoor Air Quality Performance,"
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In alphabetical order, add the following definition for occupied spaces, "Occupied Spaces are defined as enclosed spaces that can accommodate human activities. Occupied spaces are further classified as regularly occupied or non-regularly occupied spaces based on the duration of the occupancy, individual or multi-occupant based on the quantity of occupants, and densely or non-densely occupied spaces based upon the concentration of occupants in the space."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
At the end of the paragraph, remove the footnote "?"
Campus Applicable
No
Internationally Applicable:
No
1/16/2007
LEED Interpretation
Inquiry:
Residential projects without directly ducted makeup air typically get makeup air either from operable windows alone, from operable windows plus pressurized corridors, or from either or both of those sources, plus negative pressure created by bathroom fans and kitchen exhaust hoods (which may or may not be always on). For LEED NC 2.1 projects, it was asked whether CO2 monitors must be provided for low density residences. In the CIR ruling from 9/20/2004, it was confirmed that CO2 monitors for these residential spaces are not necessary to meet the intent of the credit. For LEED NC 2.2 projects, does this ruling from 9/20/2004 apply? Do residential units without ducted makeup air now require CO2 monitoring? If the ruling varies depending on the strategy by which the units receive makeup air (operable windows, pressurized corridors, bathroom and kitchen fans alone or in combination), can you indicate which scenarios require CO2 monitoring and which do not?
Ruling:
The applicant is requesting clarification on the applicability of a LEED NC 2.1 CIR ruling for LEED-NC 2.2. Under LEED-NC v2.2, EQc1 has been modified to include two methods of compliance: 1. For densely occupied areas (25 persons/ 1000 SF) use CO2 monitoring 2. For systems serving all other spaces employ outdoor air delivery monitoring Based on the information provided in this inquiry, the first option described above does not apply to individual residential units. Therefore, the second option should be followed. If the outside air (OA) supply is through a pressurized corridor, the implementation of this credit is straight forward. If OA is introduced directly to a conditioning unit (for example- a heat pump or a fan-coil unit) it may be possible to monitor OA delivery to the unit individually. For all other modes of OA supply, this credit may not be applicable. If the residential project has any densely occupied spaces such as meeting rooms, CO2 monitoring should be provided for those specific spaces.
Campus Applicable
No
Internationally Applicable:
No
8/13/2007
LEED Interpretation
Inquiry:
To monitor outside air intake we propose to utilize the DDC controls to measure temperatures for the outside air, return air, mixed air, and supply air. The DDC calculations will result in the total CFM of outside air delivered well within the 15% accuracy required. Additionally, the controls configuration will provide alarms whenever the delivered amount of outside air is below the minimum threshold. As a secondary measure, CO2 sensors will be required for ALL building tenants per the LEED CI credit EQ 1. This project exceeds the minimum ventilation requirements of ASHRAE Standard 62.1-2004 by well over 30%. These three parameters will ensure that the minimum outside air will be delivered, monitored, and alarmed per the requirements of LEED CS EQ credit 1. Will our proposal meet the intent of this credit?
Ruling:
The applicant is proposing an alternative outside air delivering monitoring device which monitors temperatures of outside air. The EQc1 credit requirement states for mechanically ventilated spaces: "For each mechanical ventilation system, provide a direct outdoor airflow measurement device capable of measuring the minimum outdoor airflow rate with an accuracy of plus or minus 15% of the design minimum outdoor air rate, as defined by ASHRAE 62.1-2004." The system proposed does not directly measure outdoor airflow rates, as flow rate cannot be measured by temperatures; therefore this strategy would not meet the credit requirements. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
7/2/2008
LEED Interpretation
Inquiry:
A roof-mounted fan delivers 100% outdoor air into a dedicated shaft duct. The fan operates using a variable frequency drive motor to maintain a constant static pressure within the shaft duct. A variable-air-volume (VAV) terminal unit located in the mechanical room on each floor of the building controls the delivery of the outdoor air from this shaft duct to the mechanical room. This VAV terminal unit is ducted on its intake side to the dedicated outdoor air shaft duct. Only outdoor air passes through this VAV terminal unit. The mechanical room acts as a mixing plenum for the outdoor air and the return air from the floor before that mixed air is drawn into the air handling unit located in the mechanical room. The air handling system is a floor-by-floor design with a single air handling unit located on each floor and serving only that floor. This VAV terminal unit contains a pressure independent primary air volume controller that controls the supply air quantity to within 5% of the airflow setpoint regardless of changes in system static pressure. This VAV terminal unit measures airflow with a pitot-tube assembly. The independent controller converts the measured velocity pressure using the known cross-sectional area to calculate the actual airflow rate. This measurement and calculation is within 5% of the airflow rate setpoint. In the "occupied" mode, each VAV terminal unit controls to the design outdoor air flow setpoint for its respective air handling system. In the "unoccupied" mode, the control damper in each VAV terminal unit is closed. The VAV terminal units controlling outdoor air to each air handling system operate based on the following sequence of operation for the control, monitoring and alarming of the outdoor airflow provided to each floor\'s air handling system: - Outdoor air fan energizes when the Energy Management System (EMS) indicates the building is in "occupied" mode. - Each VAV terminal unit in the outdoor air delivery system opens upon energizing of the outdoor air fan. - A temperature sensor at each VAV terminal unit controls the electric heater to maintain a minimum of 50 degrees F in the mechanical room. - A VAV terminal unit fails closed in the event of power loss. - The VAV terminal unit controller shall monitor and trend the outdoor air delivered to each air handling system. - Each VAV terminal unit graphic displays the measured airflow and the airflow setpoint. - If the measured airflow at a VAV terminal unit varies by more than 10% of its setpoint, an alarm message is sent to the Central Control Panel (CCP) and a notification alarm is generated to alert the building operator of this condition. With respect to carbon dioxide (CO2) monitoring, a CO2 sensor is located in the return air transfer duct at each floor\'s mechanical room. This sensor has an accuracy of +/-3% over a range of 0-2000 ppm. Each floor\'s CO2 sensor is monitored and trended by the EMS. The EMS has no less than fifty (50) points available for future tenant use as inputs for CO2 sensors installed in densely occupied areas. Does the system as outlined herein meet the requirements of LEED-CS v2 EQ Credit 1 - Outdoor Air Delivery Monitoring?
Ruling:
The approach described above will satisfy the requirements of this credit. However, the project team should make sure that the VAV setpoint is established based on the minimum outdoor air requirements of ASHRAE Standard 62.1-2004, for each floor to comply with EQp1. Additionally, the roof-mounted fan which is stated to be maintaining static pressure in the shaft duct, should provide at least the minimum outdoor air requirement of ASHRAE Standard 62.1-2004, for the building to comply with EQp1. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
3/27/2007
LEED Interpretation
Inquiry:
Our facility\'s HVAC system consists of high-efficiency, packaged, direct-fired \'Cambridge\' Unit heaters, passive intake louvers and powered exhaust fans. There is no ducted air distribution system. We propose to install airflow devices at each of the exhaust fans, instead of the intakes. We feel that this makes sense because the exhaust fans will always be \'on\', whereas the \'Cambridge\' Unit heaters will not, when heat is not required. Furthermore, it follows that measuring air being discharged from the building would be equivalent to measuring fresh air being induced into the building, since fresh air will necessarily replace exhaust air in an equal amount. Considering that this building type can be somewhat porous (when the loading dock doors are open) and, per industry norms, always under negative pressurization, it is most logical to measure air where it is being exhausted (since this necessarily will happen in a controlled way at specific locations), rather than where it is being brought in (which would be variable and would happen throughout the building). In accordance with the requirements of this credit, the airflow metering devices will be tied to alarms to alert building occupants if the prescribed airflow pattern ever fails. Finally, the minimum outside air rate (OAR) will be considerably higher than the minimum prescribed by ASHRAE 62.1-2004. The standard prescribes a minimum OAR of 0.06 cfm/sf for this building type. The specified design OAR of 3 complete air changes per 8 hour interval exceeds this minimum by a factor of 3.66. This will also allow us to achieve EQc2 - Increased Ventilation. Is this allowed?
Ruling:
The applicant is requesting an interpretation of EQc1 and proposing to monitor exhaust air-flow rather than incoming air flow. Based on the project description and conditions, it appears that this credit is not applicable. The credit is specifically intended to address issues with ventilation in environments where a fixed amount of minimum outside air is provided through a specific incoming path. Since the path of incoming air in this project can vary significantly, it would be nearly impossible to trouble-shoot any problems in the ventilation system through the proposed monitoring system. Based on the project narrative, it appears that this project would be best served by a CO2/ CO monitoring system that has alarm triggers.
Campus Applicable
No
Internationally Applicable:
No
4/24/2008
LEED Interpretation
Inquiry:
Our office has two projects that have been struggling with the requirements of EQ Credit 1. Although very different in type, they have taken similar approaches to ensuring outdoor air delivery to occupants. 1) The first project is a historic renovation of a low-rise residential building with seven units. Fresh air is delivered to the building via an Energy Recovery Unit (ERU) that exchanges exhaust air from the kitchens and washrooms of the units for 100% outside air, which is delivered to fan powered boxes in each unit. The ERU does not have an economizer or an air damper. 2) The second is the renovation of an existing doubled loaded corridor school building, which does not have a central air conditioning system, but instead uses perimeter unit ventilators to provide and heat outside air. The dampers on these units are controlled by CO2 sensors located at the thermostat, and will meet the intent of the credit. However, a few non-perimeter classrooms and offices cannot accommodate these perimeter unit ventilators, and thus has a centrally located unit ventilator that provides fresh air to these particular rooms. This ventilator also uses 100% outside air, and also has no dampers. Our suggested approach to both of these projects is to use a current transducer to monitor the performance and status of the ERU and unit ventilators, instead of using an airflow monitor as the credit requirements call for. The current of the fan varies proportionally to the load so that if the unit is malfunctioning (decreased or no airflow) it will be clearly indicated by the power being consumed by the fan. The CT monitor would then report immediately to building management who would field verify the problem and determine if maintenance is needed. We feel this approach complies with the intent of this credit for the following reasons: 1. The units are designed to run at a fixed airflow rate at all times, never to be affected by damper positions, and thus the only instance where air is not being delivered at the appropriate flow is if there is a malfunction with the unit. 2. Monitoring the outdoor airflow of units that are equipped with outdoor air dampers is useful because the dampers can be adjusted based on outdoor airflow readings. Our systems, however, do not have an outdoor air damper because they use only outdoor air. If we directly measure the outdoor airflow, the unit has no way to respond or be recalibrated to address excess CO2 in the space. Outdoor air flow monitoring could be performed, but the results would be of little use. 100% outside air systems are an important tool in providing fresh and healthy interior environments. We believe that the CT monitoring approach is the best method by which 100% outdoor air units can be measured, and also addresses the intent underlying tenets of the credit. It can be argued that outdoor airflow monitors could also provide this level of measurement (on or off), but it provides no more value or functionality than the CT monitor suggested here in the case of 100% outside air units. Please comment on whether this strategy can be used in achieving EQ credit 1.
Ruling:
The CIR is asking if current transducer (CT) monitors are adequate devices to monitor outside air delivery. For a constant volume 100% outside air system similar to the one described by the proponent, the CT approach may satisfy the credit requirement for a direct outdoor airflow measurement device, provided the CT device has been properly calibrated during the installation and commissioning process. Properly calibrated, the CT device would alert the BAS to a change in the fan status, which would indicate a change to the amount of outside air being delivered. In order to satisfy the credit requirements the submittal must show how the CT has been calibrated, and must outline the monitoring sequence. If the system is not 100% outside air, or not constant volume, the CT device would not be adequate. Note that the CT device does not relieve the project of the requirement to monitor room CO2 levels in all densely occupied spaces. -NCv2.2 Requirements state clearly that densely occupied spaces (such as classrooms - mentioned in the CIR) must have CO2 concentrations monitored. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
LEEDuser expert
Dylan Connelly
Integral Group
Mechanical Engineer
