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A BAS is the best approach
Buildings with a building automation system (BAS)A building automation system (BAS) uses computer-based monitoring to coordinate, organize, and optimize building control subsystems, including lighting, equipment scheduling, and alarm reporting., or some level of existing outdoor airflow monitoring, have the best shot at this credit, which can help you to monitor and maintain adequate ventilation levels throughout the building. If your building does not have a BAS, compliance will be more challenging.
Most buildings don’t already have the proper monitoring devices, and device installation along with the configuration of the existing ventilation system may make this credit time-consuming, challenging, and costly. Parts and labor costs are directly related to the quantity of densely occupied spacesDensely 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)., and the number of sensors that must be purchased and installed.
Install permanent monitoring systems
This credit requires installation of permanent, continuous monitoring systems that alert building operators when outdoor airflow in the building drops more than 15% below the minimum set point. Generally, every building that uses mechanical ventilation must install and maintain permanent outdoor airflow measurement devices in the outdoor air intakes to comply with this credit. These sensors must provide continuous monitoring and trigger an alarm for the building operator if the minimum outdoor airflow rate falls more than 15% below the design minimum rate.
If your building contains any densely occupied spaces, you must also install CO2 sensors, but only in those spaces, to provide added indicators of reduced indoor air quality due to inadequate ventilation.
Follow each case in tandem
Many project teams need to follow the guidelines for Case 2 in addition to Case 1, if densely occupied spaces total more than 5% of total occupied square footage.
Common examples of densely occupied spaces include, but are not limited to:
- conference rooms,
- classrooms,
- presentation halls,
- cafeterias,
- and exercise facilities.
Case 2 requires CO2 sensors to be installed in these spaces. CO2 sensors are important here because they support the adjustment of the mechanical system to changes in daily use.
For example, a meeting room with five occupants may be adequately ventilated, but if the same room holds 25 occupants for another meeting, the ventilation may not be sufficient. A buildup of CO2 in a densely occupied space will trigger an alarm, alerting building managers or operators that the ventilation set points must be adjusted to maintain good occupant comfort.
Natural ventilation is possible
It is possible to earn this credit with a natural ventilation system, but there have not been many cases of it, simply due to the relatively low number of naturally ventilated buildings attempting LEED-EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. certification.
Natural ventilation is covered by Case 3, and any building has to follow this case if more than 5% of occupied spaces are naturally ventilated.
Consider these questions when approaching this credit
- Does your building have a history of problems with adequate outdoor air delivery, such as complaints of stale air, a “stuffy” feeling, or odors? If so, it would probably benefit from the use of these monitoring devices and practices.
- Does your building have variable ventilation loads due to changes in use from hour to hour or day to day? These buildings might see energy efficiency benefits from monitoring devices due to an increased ability to modulate loads.
- Does your building contain densely occupied spaces? These are areas that have a design occupant density of 25 people or more per 1,000 ft2. If so, does the total square footage of all densely occupied space exceed 5% of the total occupied square footage? If it does, you must follow the Case 2 guidelines in densely occupied spaces, in addition to the Case 1 guidelines, in order to earn this credit.
- Do you already use a BAS to manage HVAC in your building? If so, are you using sensors to monitor airflow rate and CO2 concentration in occupied spaces?
Legend
- Best Practices
- Gotcha
- Action Steps
- Cost Tip
USGBC
Excerpted from LEED 2009 for Existing Buildings: Operations & Maintenance
IEQ Credit 1.2: Indoor air quality best management practices - outdoor air delivery monitoring
1 point
Intent
To provide capacity for ventilation system monitoring to help sustain occupant comfort and well-being.
Requirements
Install permanent, continuous monitoring systems that provide feedback on ventilation system performance to ensure that ventilation systems maintain minimum outdoor airflow rates under all operating conditions.
AND
Case 1. Mechanical ventilation systems
Provide an outdoor airflow measurement device capable of measuring (and, if necessary, controlling) the minimum outdoor airflow rate at all expected system operating conditions within 15% of the design minimum outdoor air rate. Monitoring must be performed for at least 80% of the building’s total outdoor air intake flow serving occupied spacesOccupied 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..
The outdoor airflow measurement device(s) must take measurements at the system level (i.e., the air-handling unit). The device must be monitored by a control system that is configured to trend outdoor airflow in intervals no longer than 15 minutes for a period of no less than 6 months. The control system must be configured to generate an alarm visible to the system operator if the minimum outdoor air rate falls more than 15% below the design minimum rate.
All measurement devices must be calibrated within the manufacturer’s recommended interval.
Case 2. Mechanical ventilation systems that predominantly serve densely occupied spaces1
Have a CO2Carbon dioxide sensor or sampling location for each densely occupied space and compare it with outdoor ambient CO2 concentrations. Each sampling location must be between 3 and 6 feet above the floor.
Test and calibrate CO2 sensors to have an accuracy of no less than 75 parts per million (ppmParts per million.) or 5% of the reading, whichever is greater. Sensors must be tested and calibrated at least once every 5 years or per the manufacturer’s recommendation, whichever is shorter.
Monitor CO2 sensors with a system configured to trend CO2 concentrations in intervals no longer than 30 minutes. The system must generate an alarm visible to the system operator and, if desired, to building occupants if the CO2 concentration in any zone rises more than 15% above that corresponding to the minimum outdoor air rate required by IEQ Prerequisite 1.
CO2 sensors may be used for demand-controlled ventilation provided the control strategy complies with ASHRAE Standard 62.1-2007 ventilation rate procedure (see IEQ Prerequisite 1: Minimum Indoor Air Quality Performance, including maintaining the area-based component of the design ventilation rate).
Case 3. Natural ventilation systems
Locate CO2 sensors in the breathing zoneThe breathing zone is the region within an occupied space between 3 and 6 feet above the floor and more than 2 feet from walls or fixed air-conditioning equipment. (AHSRAE 62.12007) of every densely populated room and every natural ventilation zone.
CO2 sensors must provide an audible or visual alarm to the occupants in the space and to the system operator if CO2 conditions are greater than 530 ppm above outdoor CO2 levels or 1,000 ppm absolute. The alarm signal must indicate that ventilation adjustments (e.g. opening windows) are required in the affected space.
All monitoring devices must be calibrated within the manufacturer’s recommended interval.
Permanently open areas must meet the requirements of ASHRAE 62.1-2007, Section 5.1 (with errata but without addenda2).
Exemptions: If the total square footage of all space served by natural ventilation systems is less than 5% of total occupied square footage, the project is exempt from the requirements of this section. Rooms smaller than 150 square feet are also exempt.
Potential Technologies & Strategies
Install and maintain permanent ventilation monitoring systems that provide feedback on system performance to ensure minimum ventilation rates.
Organizations
ASHRAE
The ASHRAE website provides industry updates and standards. ASHRAE standards relevant to this credit include ASHRAE 55 2004: Thermal Comfort Conditions for Human Occupancy, and ANSI/ASHRAE 62.1 2007: Ventilation for Acceptable Indoor Air Quality.
Publications
Building Air Quality: A Guide For Building Owners and Facility Managers
This guide is for preventing, identifying and resolving IAQIndoor air quality: The quality and attributes of indoor air affecting the health and comfort building occupants. IAQ encompasses available fresh air, contaminant levels, acoustics and noise levels, lighting quality, and other factors. problems in existing commercial and public buildings.
Technical Guides
Standard Guide for Using Indoor Carbon Dioxide Concentration to Evaluation Indoor Air Quality and Ventilation, ASTM Standard D 6245-98, 2002
This standard from the American Society for Testing and Materials describes how measured values of indoor CO2 concentrations can be used to evaluate indoor air quality and building ventilation.
ANSI/ASHRAE 62.1 Users’ Manual Appendix A
This site provides information on CO2 sensors and demand-controlled ventilation.
IEQ Space Matrix
This spreadsheet categories dozens of specific space types according to how they should be applied under various IEQ credits. This document is essential if you have questions about how various unique space types should be treated.
Sample LEED Online Form
Use this sample LEED Online form with annotations to review how to properly document this credit.
LEED Online Forms: LEED-EBOM IEQ
The following links take you to the public, informational versions of the dynamic LEED Online forms for each EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems.-2009 IEQ credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.
Version 4 forms (newest):
- IEQp1: Minimum IAQ Performance
- IEQp2: ETS Control
- IEQc1.3: Increased Ventilation
- IEQc1.4: Reduce Particulates
- IEQc2.4: Daylight & Views
- IEQc3.2: Custodial Effectiveness Assessment
Version 3 forms:
- IEQp1: Minimum IAQ Performance
- IEQp2: ETS Control
- IEQp3: Green Cleaning Policy
- IEQc1.1: IAQ Management Program
- IEQc1.2: Outdoor Air Delivery Monitoring
- IEQc1.3: Increased Ventilation
- IEQc1.4: Reduce Particulates
- IEQc2.1: Occupant Comfort—Occupant Survey
- IEQc2.2: Controllability of Systems—Lighting
- IEQc2.3: Controllability of Systems—Thermal Comfort
- IEQc2.4: Daylight & Views
- IEQc3.1: High-Performance Cleaning Program
- IEQc3.2: Custodial Effectiveness Assessment
- IEQc3.3: Purchase of Sustainable Cleaning Products
- IEQc3.4: Sustainable Cleaning Equipment
- IEQc3.5: Chemical & Pollutant Source Control
These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictions for these forms; for more information, visit LEED Online and click "Sample Forms Download."
LEEDuser is produced by BuildingGreen, Inc., with YR&G authoring most of the original content. LEEDuser enjoys ongoing collaboration with USGBC.
23 Comments
Densely occupied spaces exemption
Hi All,
We have a project that has a lot of meeting rooms (area of each room is smaller than 150 square feet) that can accomodate 4 person per meeting room - therefore considered densely occupied and should be provided with CO2Carbon dioxide sensors. However, the reference guide states that individual rooms smaller than 150 square feet are exempted. Which will govern?
Hi Mary Ann
The exemption for rooms smaller than 150 square feet would be the overriding factor.
Thanks,
Hannah
It'd be nice if GBCI would apply this minimum to all project types not just EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems.. There are a number of credits across all the project types where a minimum SQFT would help take into account a reasonable ROI. Maybe in v4!
Hi Dylan
Did you see the 5th public comment for LEED v4 is open? I'd strongly recommend adding your comments here if you haven't already: https://new.usgbc.org/
CO2 Sensors
I'm trying to get an idea of where CO2Carbon dioxide sensors would be required on a project. It is an office building with one AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. per floor and one for a fitness center. The building contains several densely occupied spacesDensely 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). (conference rooms and the fitness center).
It is unlikely that any of the AHU's are predominantly serving densely occupied space (except for the fitness center AHU). Assuming that this is the case, I believe that the fitness center is the only space that would require a CO2 sensor. Is this correct?
Michael
From my understanding, you will need to take the following approach to meet the credit requirements:
For each AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork., you will need to determine if the densely occupied areas make up 5% or more of the total floor area for that floor. If this is true, then you will need to install CO2Carbon dioxide sensors in all of the densely occupied spacesDensely 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). served by that AHU. If not, then there is no need to install CO2 sensors on that floor.
I would take this approach for each AHU and then provide a table showing the 5% rule and if it's applicability for each AHU as a part of your supporting documentation.
Hope this helps,
Hannah
There is still some confusion on my end; reading through the reference guide, it seems that Case 2 is only applicable when an AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. is predominantly serving densely occupied spacesDensely 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).. But from reading on here, it looks like Case 2 is applicable in all cases where the densely occupied spaces account for >5% of total occupied building area.
The safe bet here is to apply the 5% rule and put sensors in all of those densely occupied spacesDensely 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). in your building. I'd especially urge you to go this route because I'd hate to see the credit denied after a large financial investment is made. Let me know how else I can help.
We found a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide regarding this: "All densely occupied spacesDensely 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). must include CO2Carbon dioxide sensors. If the AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. predominantly serves densely occupied spaces, outdoor airflow measurement at the AHU is not required. If the AHU predominantly serves non-densely occupied spacesNon-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).", outdoor airflow measurement at the AHU is required, in addition to CO2 sensors in the densely occupied spaces."
I've tried to answer this for my self with your conversation, but are there exceptions to these rules for densely occupied spacesDensely 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). that go through various configurations with air/movable walls (ie ballrooms). It would be impossible and ineffective to install sensors on temporary walls. the ceiling would be the only logical place but that is out of the breathing zoneThe breathing zone is the region within an occupied space between 3 and 6 feet above the floor and more than 2 feet from walls or fixed air-conditioning equipment. (AHSRAE 62.12007)
Outdoor Airflow Measurement with constant volume ventillation
Our building measures the outdoor airflow at the AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork.. As we have a constant volume system (fan-coils) with 100% fresh air, from that point onward the airflow is not varied. The balancing of the system was checked and confirmed as part of the commissioning process, thus the volume of fresh air delivered to each zone only changes if the outdoor air volume changes at the AHU.
Do we need to have separate outdoor airflow measurement devices for every zone, or is the installed system level measurement device sufficient to meet the credit requirements?
Measuring OSA at the AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. is sufficient. The airflow to the FCUs will be proportional from that point on based on the balancing.
Hi Dylan,
Just to confirm, if the entire building is conditioned with 100% OA, do we still require to measure it, even though we already know the volume of air entering the building with the system specs?
Yes you still need to measure the air by some means. Sonrisa Lucero pointed out that "LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. #2099 addresses using CTs (circuit transducers providing fan status) for constant volume and 100% OA systems as an alternative to the airflow station to comply with this credit."
CO2 testing
Need to know if I need to do a CO2Carbon dioxide test on Case 1 Mechanically Ventilated spaces.
No, you don't—see the flow chart and other information above.
Natural Ventilation
Our building is mostly naturally ventilated. One of the seven floors, however, has a central air system installed that serves three densely occupied conference rooms. Which case (or cases) do we need to follow? All 3?
In addition, we do not currently have a Building Automation System. Will this be required to achieve this credit? Is a BAS required for Case 3?
Any comments or suggestions would be greatly appreciated. Thank you!
Melissa, from what you say it sounds like cases 2 and 3 are appropriate here.
A BAS is not strictly required to earn the credit, but as discussed above, it helps. Given that the area subject to case 2 is relatively concentrated, though, perhaps it would be cost-effective to pursue the credit without a BAS.
Definition of Occupied Space
LEED EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. ed 2009, page 366, 1st paragraph, "if total SF of all dense space is less than 5% of total occupied SF for the project building, the requirement......."
what is the definition of occupied space? does elevator , restroom, lobby, storage room, etc, consider occupied space which has outdoor air flow served to these area?
Jason - I'd love to hear others input on this, but the Reference Guide doesn't seem to define either 'occupied square footage' or the related term 'REGULARLY occupied square footage.' I would assume that the former is effectively the actual interior space of the building (excluding walls, partitions, structural elements, etc...) while the latter further excludes portions of the occupied SF which are not actually occupied by people most of the time - I would exclude the elevator, storage rooms, mechanical rooms etc... and then waffle about what to do with bathrooms and lobbies. Any other ideas out there?
Does IEQp1 Case 2 qualify for this measure?
Our contractor is telling us we can not meet 62.1-2007 because we do not have the chiller capacity, but we can meet the 10 cfm/person requirement of case 2. If we go this route, does this disqualify us from attempting IEQc1.2?
I don't think that IEQp1 case 2 is necessarily counter to IEQc1.2. Do you think you can meet the IEQc1.2 requirements?
That is the plan. We hired this contractor to ensure we met IEQp1, and install monitoring for IEQc1.2. We are trying to ensure p1: Case 2 won't hinder our plans for achieving c1.2.
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