CS-2009 IEQc1: Outdoor Air Delivery Monitoring

  • Outdoor Air Delivery Monitoring requirements diagram for NC, CS, Schools, and CI

  • Fresh air and energy savings

    Outdoor air delivery monitoring ensures that the ventilation system, whether natural or mechanical, provides enough fresh air to occupants. The credit  requires carbon dioxide (CO2) and outdoor airflow monitors that signal when fresh air is needed according to minimum set points defined by ASHRAE 62.1-2007. Typical ventilation design (without monitors) tends to encourage increased ventilation that may result in increased energy use and added cost for conditioning increased amounts of outside air. However, the addition of sensors and monitors allows ventilation to be delivered on demand only when required, potentially saving a lot of energy during unoccupied hours in spaces with varying occupancy.

    Crowded auditoriumA space with high-density occupancy at different times of day can be a great fit for this credit.

    Good for buildings with varying occupancy rates

    For buildings with varying occupancy rates and centralized mechanical systems, like offices and schools, the added cost should be minimal, and the systems will probably reduce energy bills, offering good return on investment. High-density areas like conference rooms, theaters, and congregation spaces are a particularly good match for this credit.

    In multifamily or hotel projects, or any building with numerous isolated mechanical systems or natural ventilation, more sensors will be needed, making this credit relatively expensive to pursue.

    Use these questions to help explore this credit

    • Will the project have natural, mechanical or mixed-mode ventilation?
    • If the project is mechanically ventilated, will it be a centralized system? Centralized systems can achieve this credit more cost-effectively.
    • If naturally ventilated, will the project include designs that allow for adequate ventilation without human interaction?
    • Will the design include a BMS or demand control ventilation? These systems can make credit achievement easier.
    • What is the cost increase associated with CO2 sensors and outdoor air monitors?
    • Does the local utility offer any rebates on incentives on CO2 sensors, outdoor air flow monitors or demand control ventilation?
    • If the project is a hotel or multifamily, does installing CO2 sensors in each room seem cost-effective and beneficial?
    • If the project is a laboratory, can CO2 and other small particulates be monitored to provide ventilation only when needed? If so, this credit can be very cost-effective.
    • Are CO2 sensors or outdoor air monitors compatible with existing mechanical equipment and is the building owner willing to install these monitoring systems?
    • Which spaces are densely occupied and which are non-densely occupied?

    FAQs for IEQc1

    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?

    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, issued 4/24/2008, allows the use of circuit transducers that measure fan status of 100% outside air and constant volume fan systems as an alternative to an airflow measuring station for this credit. For constant volume and 100% outside air systems that have been accurately balanced, monitoring the fan status is adequate to maintain proper outside air volumes. This is not an appropriate strategy for variable volume systems.

Legend

  • Best Practices
  • Gotcha
  • Action Steps
  • Cost Tip

Schematic Design

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  • Determine the best ventilation strategy for your building: natural, mechanical, or mixed-mode ventilation. The choice of ventilation system is more likely to be shaped by the LEED minimum ventilation prerequisite (IEQp1) and increased ventilation credit (IEQc2), not this credit.

  • Consider incorporating CO2 sensors or outdoor airflow monitors into the building design, as required by the credit. Discuss with the project team the indoor air quality (IAQ) and energy benefits of installing monitoring devices in the project.

  • Outdoor airflow monitoring devices are the single most costly component of this credit, ranging from $1,000–$5,000 per monitor, depending on size of the ducts and product type. You can reduce this cost by minimizing the number of supply ducts coming into the building. Centralized systems minimize these ducts, thereby minimizing cost.

  • CO2 sensors are not standard practice and typically cost $500–$1000 per sensor including installation. Installing CO2 sensors is becoming more common and this price may come down, however. Costs can add up quickly if several sensors are required. In applications with many densely occupied spaces and isolated mechanical systems, like hotels and multifamily, providing CO2 sensors and the associated controls for each unit could become costly, without much added benefit. However, in applications with larger, densely occupied spaces served by centralized mechanical systems—such as office spaces—CO2 sensors become significantly more cost-effective, as ventilation demand is matched to occupancy and the HVAC system operates only when the room is occupied or to meet established set points.

  • CO2 sensors are not the same as CO sensors. CO (carbon monoxide) sensors are much more common, inexpensive, and do not need to be hard wired. Make sure this distinction is clear when talking with the owner, mechanical engineer, and building operator.

  • Consider the impact of monitoring devices on space and design requirements. Issues to consider include the location of CO2 sensors, the inclusion of outdoor air monitors when designing the mechanical system, and whether to use a building management system (BMS), which allows your ventilation system to automatically respond to changing indoor situations.

  • Demand Control Ventilation (DCV) in conjunction with CO2 sensors can serve the dual purpose of energy conservation and improved indoor air quality. They provide the option of additional ventilation only when CO2 sensors indicate that it is necessary.

  • Outdoor air can contain contaminants that lead to unhealthy working or living conditions. You may need to assess the quality of the local outdoor air before bringing it indoors. HHigh efficiency MERV filters (13 or higher) are one solution to treating poor-quality outdoor air before supplying it to the indoors. This can be part of a strategy for achieving IEQc5: Indoor Chemical and Pollutant Source Control.

  • CO2 sensors are not required in tenant spaces that are not included in the scope of work for the LEED project. However, in order to achieve credit compliance, the base building’s mechanical system and BMS must be capable of incorporating CO2 sensors into future tenant fit-outs. Including requirements for monitoring systems in tenant lease or sales agreements is recommended to help tenants earn a LEED for Commercial Interiors credit for CO2 monitors.

  • Continuous airflow and CO2 monitoring is required. Air balancing measures such as total airflow measurement and static pressurization measurements do not comply with the credit requirements.

  • Projects without ducted make-up air must follow Option 2 for natural ventilation, and should weigh the costs and benefits of installing monitoring devices. For example, in multifamily projects and hotels where outside air is only supplied through pressurized hallways and operable windows. Every apartment or unit will need one CO2 sensor per unit, and many projects find this to be too costly. Mechanically ventilated common areas such as hallways and lobbies will require outdoor airflow monitors instead of CO2 sensors.

  • CO2 sensors do not provide the same benefit in non-densely occupied spaces as they do in densely occupied spaces. It is important to remember that CO2 sensors measure only CO2 generated by human occupants and they are typically not a good way to indicate indoor air quality in non-densely occupied spaces. CO2 monitors cannot replace outdoor air monitors and are often incorrectly preferred because they are less expensive than outdoor air delivery monitoring.

  • Some utilities offer rebates for installing CO2 sensors in conjunction with demand-control ventilation. For example, the New York State Energy Research and Development Authority (NYSERDA) and Florida Power & Light have offered such incentives. Check with your local utility or DSIRE to see if rebates are available in your area (see Resources).

  • CO2 sensors will provide the highest return on investment in areas where the occupancy is intermittent or unpredictable. Examples include conference rooms and auditoriums, where ventilation rates will need to be high only when close to full occupancy and where ventilation rates can be low when the spaces are unoccupied.

  • Fees for engineering services may increase due to this credit, because of the need to develop controls sequences. That premium can be reduced if the engineer has experience with the credit in similar applications.

  • The cost of alarms and BMS equipment varies greatly and is dependent on the complexity of the system.

Design Development

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  • The project team and contractor work together to determine the feasibility and rough cost increase of including CO2 sensors or outdoor airflow measurement devices.

  • The owner, mechanical engineer and building operator should determine the best option for corrective action in the project. Options for corrective action include opening windows, adjusting air-handling units, alerting tenants, and increasing ventilation flow rates.

  • Use ASHRAE standard 62.1-2007 to determine outside air requirements.

  • The mechanical engineer and architect identify densely and non-densely occupied spaces as defined by LEED and determine the quantity and locations of all monitoring devices, and integrate them into the HVAC system. The mechanical engineer should verify that the monitors are designed to interface with a BMS system or trigger an audible or visual alarm if CO2 concentrations or ventilation rates fall outside of the required range.

  • All monitoring devices must be able to trigger an alarm or automated response when actual measurements vary by 10% or more in either direction from the design set points. The signal or alarm is most often relayed to a building management system that balances supply and return air volumes, monitors and controls minimum fresh air volumes, and provides a reliable reference point for commissioning of VAV systems. The alarm can be audible or visual and be relayed to building facility staff or directly to the occupants, to alert them to open windows.

  • The benefits of any monitoring device depend on the communication system, response and corrective action. Facility operators often find it very beneficial to automate the response by installing demand-control ventilation, which automatically regulates airflow as needed.

  • CO2 sensors can 1) measure the indoor concentrations of CO2 and compare them against ASHRAE 62.1-2007 limits or, 2) measure the indoor concentrations of CO2 and compare them against outdoor CO2 concentrations. If you choose the second option, you will need to install outdoor CO2 monitors as well.

  • Naturally Ventilated Buildings

  • All occupied spaces in naturally ventilated buildings require the installation of at least one CO2 sensor. The number of CO2 sensors depends on the project’s design and should be calculated by the mechanical engineer. Projects can use one CO2 sensor for multiple spaces only if the project is ventilated by an approved “engineered natural ventilation system” according to ASHRAE 62.1-2007 requirements and if it does not require occupant intervention. This type of ventilation system connects adjacent spaces via air pathways that utilize the stack effect, or passive air movement from openings at a lower level than the point of exhaust. A single CO2 sensor can be used in these connected spaces. To meet the credit requirement, an engineer must demonstrate that the natural ventilation system can maintain adequate ventilation rates.

  • Mechanically Ventilated Buildings

  • All densely occupied spaces in mechanically ventilated buildings require the installation of at least one CO2 sensor per space. Non-densely occupied spaces require an outdoor airflow (OA) monitoring device. For mechanically ventilated spaces, the CO2 sensor has to be installed for the zone being served by one ventilation system. The credit requires only one sensor per space, but installing multiple sensors within a large space helps measure varying concentrations of CO2.  For example, if the sensor is located in one location, while people are congregating in another corner of the same space, the sensor will not recognize the high CO2 concentrations. Spread the sensors out to accommodate for more uses of the space. Also, use at least one sensor per ventilated zone, for a large space being served by multiple zones. Consult the mechanical engineer on the quantity and placement of CO2 sensors.

  • For mechanical ventilated spaces that are installing a BAS or BMS, the system should be capable of integrating with the CO2 sensor and outdoor air flow monitors for immediate response with increased fresh air, such as demand-control ventilation.

  • Airflow measurement devices are installed as part of the air duct system and are designed to measure airflow and transmit a signal when airflow deviates from established set points. Two common types of these devices are those that measure intake volume directly by measuring air velocity (advanced thermal dispersion) and those that measure differential pressure across a fixed opening (pitot arrays and flow-rings). Both can provide the accuracy required for the credit. Advanced thermal diffusion is more accurate and requires less maintenance, but is more expensive.

  • CO2 monitors installed in return-air ducts (in the ceiling or floor) will not meet the credit requirements, as monitors are required to be placed 3–6 feet above the floor in all densely occupied spaces.

  • In laboratory and health care facilities, consider continuously measuring additional air quality factors such as TVOCs, carbon monoxide, and other small airborne particulates to reduce ventilation rates down to two air changes per hour (ACH), as conditions permit, in order to save energy.

  • Integrating an ERV or HRV into a system that meets the Outdoor Air Delivery Monitoring credit can be particularly cost-effective with large centralized systems.

  • Demand-control ventilation can help reduce peak load allow you to select smaller mechanical systems, minimizing upfront costs.

  • Not all conference rooms are densely occupied spaces! Densely occupied spaces are defined as having 25 people per 1,000 square feet of space.

Construction Documents

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  • Include CO2 sensors and outdoor air delivery monitoring devices on the project plans and Equipment Schedule. Also highlight the interface between monitors and BMS or alarm on project plans.

  • Review drawings to ensure that all densely occupied spaces contain CO2 sensors.

  • Detailed construction instructions with locations of monitoring devices help to ensure that these devices are installed correctly.

  • Outdoor airflow monitors may be integrated within AHUs and ventilation equipment specifications.

  • The monitoring and alarm systems need to be included in the commissioning plan for EAp1: Fundamental Commissioning with the appropriate sampling rate.

  • The outside air delivery monitoring device should be specified along with the Air Handling Unit (AHU) equipment package.

  • Ensure that monitoring devices are included in budget estimates from the beginning to avoid any surprises.

  • Document credit compliance on LEED Online. This credit has an LPE path for Professional Engineers where project plans, drawings, and other information is not necessary for upload. For the full documentation path you will need to complete the following:

    • Mechanical ventilation
      • Provide the completed ASHRAE 62.1-2007 calculator.
      • Provide controls drawings showing outdoor airflow measurement devices serving non-densely occupied spaces.
      • Provide detailed information on outdoor air ventilation rates (including required air flow rate, accuracy of devices and setpoints).
      • The controls designer will need to sign the LEED Online credit form stating that the monitoring devices meet the credit requirements.
      • Proivde drawings showing the location of CO2 sensors for densely occupied spaces.
      • Provide a list of densely occupied spaces
      • The controls designer will need to sign the LEED Online credit form stating the CO2 sensors are programmed to generate an alarm.
    • Natural Ventilation
      • Provide a drawing showing the zones, windows and location of CO2 sensors.
      • The controls designer must sign the LEED Online credit form stating that CO2 sensors are installed in all naturally ventilated spaces, are located in the breathing zone, and will generate an alarm.

Construction

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  • Contractor installs the monitoring devices as recommended by product manufacturer and mechanical engineer. Verify that all alarms have set points complying with ASHRAE 62.1-2007.

  • Verify that CO2 sensors are 3–6 feet off the floor.

  • The commissioning plan should include HVAC, monitoring, and alarm systems, with the appropriate sampling rate.

  • Integrating an automated BMS requires a highly skilled construction team. The BMS is a complex tool requiring skilled personnel who understand the controls and settings as applicable to the project.

  • Ensure that CO2 sensors and outdoor air monitors, and installation costs are incorporated into the detailed budget from the bid documents through final contracts. CO2 sensors are not common, and although the mechanical engineer is responsible for accounting for them on drawings, they could be a forgotten detail.

  • During the buyout phase, ensure CO2 sensors are included in the mechanical or controls contractor’s scope of work.

Operations & Maintenance

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  • Monitor and recalibrate the monitoring and alarm systems as specified by the product manufacturer.

  • Occupant behavior is likely to evolve over the first few months of occupancy. If the building has a BMS, the control sequence, timers, thermal setpoints and other parameters might need to be tweaked for some time. Use the outdoor air monitoring and CO2 sensors to maintain good indoor air quality as well as efficiency.

  • Train facilities personnel to use systems as intended. Facilities personnel should be given all appropriate product data.

  • When alarms are activated by CO2 monitoring devices, facilities personnel and building occupants, if appropriate, need to be aware of the needed corrective measures, such as opening windows or changing AHU settings. The alarm should be visible enough to be noticed.

  • Include the alarm system in the occupant survey for IEQc7.2: Thermal Comfort—Verification to determine its effectiveness.

  • CO2 sensors and outdoor air flow monitors will need recalibration and maintenance, which will bring a minimal additional cost. If they are not recalibrated, there is potential for overventilation or underventilation, and consequently, unnecessary energy consumption or reduced indoor air quality.

  • USGBC

    Excerpted from LEED 2009 for Core and Shell Development

    COPYRIGHT © 2009 BY THE U.S. GREEN BUILDING COUNCIL, INC. ALL RIGHTS RESERVED

    IEQ Credit 1: 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 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 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). 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 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).".

    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.

    Potential Technologies & Strategies

    Install CO2Carbon dioxide and airflow measurement equipment and feed the information to the heating, ventilating, and air conditioning (HVAC) system and/or 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. to trigger corrective action, if applicable. If such automatic controls are not feasible with the building systems, use the measurement equipment to trigger alarms that inform building operators or occupants of a possible deficiency in outdoor air delivery.

    Installation of CO2 sensors in tenant spaces is not required during core and shell construction, and tenants are not required to install CO2 monitors; however, they should be made aware of the capability of the core and shell system to monitor CO2. The core and shell systems must be designed with the capacity for CO2 monitoring. This entails a building automation system that can be expanded to include future tenant CO2 points.

    FOOTNOTES

    1 Project teams wishing to use ASHRAE approved addenda for the purposes of this credit may do so at their discretion. Addenda must be applied consistently across all LEED credits.

Technical Guides

ASHRAE 62.1-2007: Outdoor Airflow Monitoring Devices.

ASHRAE 62.1-2007 should be referenced when designing outdoor airflow monitoring devices.

Indoor Air Quality Building Education and Assessment Model (I-BEAM)

I-BEAM is a comprehensive tool for building professionals and others responsible for indoor air quality in commercial buildings; it provides state-of-the-art guidance for managing Indoor Air Quality in commercial buildings.

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.

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.

Energy Cost and IAQ Performance of Ventilation Systems and Controls Study

A study on the compatibilities and tradeoffs between energy and ventilation, which gives an idea of strategies that best meet both objectives.

Indoor Air: International Journal of Indoor Environment and Health

This journal presents research to help designers, owners and operators provide healthy buildings.

Organizations

Database of State Incentives for Renewables and Efficiency (DSIRE)

This database shows state-by-state incentives for energy efficiency, renewable energy, and other green building measures. Included in this database are incentives on demand control ventilation, ERVs, and HRVs.

Design Narrative

All Options

Use a narrative to describe how your project meets the requirements for outside air monitors and carbon dioxide monitors.

Compliant Products

Use manufacturer cut sheets to find credit-compliant products and to document compliance when necessary.

Design Submittal

PencilDocumentation for this credit can be part of a Design Phase submittal.

44 Comments

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Mary Ann Santos
Mar 12 2013
LEEDuser Member
1221 Thumbs Up

Lease Agreement an option to comply with the credit requirements

Hi,
We are currently documenting the requirements for this credit and our option in order to comply is to provide a Tenant/Lease Agreement. The LEED requirement says, "provide the legally binding document associated with the project, signed by both the developer and the tenant, explicitly stating the performance requirements for the tenant work." Since at this time, it is still unknown to the owner who will be occupying the tenant spaces and no one has to sign yet for the tenant. What other options can we do to meet the requirement? Please advise. Thanks a lot!

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Marcio Alberto Casado Pereira
Jan 10 2013
LEEDuser Member
999 Thumbs Up

Calculating CO2 Concentrations in a Zone

Hi!

I'm finishing a project and must indicate the levels to be configured in ppmParts per million. CO2Carbon dioxide sensor environments.

As an example, I have a training room with 8 people and an area of ​​497.29 sf. The project has a mechanical ventilation system with a flow rate of 254 cfm.

What value do I indicate the sensor? How do I know the ppm level as the project?
How do I calculate it?

Thanks!

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Michael Smithing Director - Green Building Advisory, Colliers International Jan 14 2013 LEEDuser Member 813 Thumbs Up

CO2Carbon dioxide sensor values are typically set relative to the outside environment. I found this table, which appears to be in line with most discussions I've had with experts:
- normal outdoor level: 350 - 450 ppmParts per million.
- acceptable levels: < 600 ppm
- complaints of stiffness and odors: 600 - 1000 ppm
- ASHRAE and OSHA standards: 1000 ppm
- general drowsiness: 1000 - 2500 ppm
- adverse health effects expected: 2500 - 5000 ppm
- maximum allowed concentration within a 8 hour working period: 5000 ppm

If you set the sensor for 600 ppm you should be OK.

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Michael E. Edmonds-Bauer Edmonds International
Dec 11 2012
LEEDuser Member
77 Thumbs Up

NO DENSILY OCCUPIED SPACE IS AT OUR PROJECT

Our project is a CS building with only a few areas within the reach of control of de developer, basically the building staff offices and they will never reach 25 people per 1000 sqft.

Does this mean that we are not required to install the CO2Carbon dioxide censor at 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. and by only providing the outdoor aire delivery monitoring will achieve the credit?

I was thinking having the owner signing a document stating that, in case the density of the CS building increases this CO2 monitors will be installed but for now since we do not have any densily occupied space no CO2 monitor will be on the project.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Dec 14 2012 LEEDuser Moderator

Michael, if there are no 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)., then you do not need CO2Carbon dioxide sensors to earn the credit. However, a CS building typicaly needs a tenant lease agreement to earn this credit—see CS Appendix 4 in the LEED Reference Guide.

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Adam Targowski Owner, ATsec Dec 17 2012 LEEDuser Member 577 Thumbs Up

Tristan, doesn't the lease agreement refer only to the outdoor air flow monitoring in case the tenant is in charge of installing his own ventilation system? I understood that we don't have to require tenants to install their own CO2Carbon dioxide sensors.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Dec 17 2012 LEEDuser Moderator

Adam, where did you get those ideas?

Keep in mind this is a credit and thus optional. If you don't plan to meet the requirements, then you don't need to try to earn the credit.

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Adam Targowski Owner, ATsec Dec 17 2012 LEEDuser Member 577 Thumbs Up

I got these ideas from the section "Checklists" above that says: "CO2Carbon dioxide sensors are not required in tenant spaces that are not included in the scope of work for the LEED project. However, in order to achieve credit compliance, the base building’s mechanical system and BMS must be capable of incorporating CO2 sensors into future tenant fit-outs." I got those ideas also from some comments below. One of them (the discussion started on Sep 14 2010) is quoting 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 answer: "Per the LEED Design and Construction Reference Guide, project teams may want to design control systems with the capability for future expansion to allow CO2 monitoring 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).; however, this is not required for compliance with this credit under the LEED Core & Shell rating system".
That is why I asked this question. The reference guide is not always clear about some requirements and very often I can hear different opinions from different people.

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Noriko Yasuhara CSR Design & Landscape Co., Ltd.
Dec 09 2012
LEEDuser Member
351 Thumbs Up

"tenants are not required to install CO2 monitors"?

From Leeduser.com, CS-2009/IEQc1, Credit Requirements, Potential Technologies & Strategies:
"Installation of CO2Carbon dioxide sensors in tenant spaces is not required during core and shell construction, and tenants are not required to install CO2 monitors; however, they should be made aware of the capability of the core and shell system to monitor CO2. The core and shell systems must be designed with the capacity for CO2 monitoring. This entails a building automation system that can be expanded to include future tenant CO2 points."

From LEED ONLINE:
"For all spaces where the scope of anticipated tenant work will include outdoor air delivery monitoring elements addressed in IEQ Credit 1, the tenant sales and/or lease agreement contains binding language specifying the minimum criteria for ventilation monitoring systems and monitoring
of mechanically and naturally ventilated spaces such that spaces within the scope of anticipated tenant work shall comply with the requirements of IEQ Credit1 when completed."

LEEDuser.com's text on tenant scope of work on outdoor air delivery monitoring seems misleading, please check and update it if necessary.

Thanks!

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Dec 14 2012 LEEDuser Moderator

Noriko, the LEEDuser content you are quoting is in fact the verbatim LEED credit language from the USGBC credit library. Any discrerpancy is between two different statements being made by USGBC.

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Tony Schafer
Mar 02 2012
Guest
158 Thumbs Up

Achieving IEQc1 with no ventilation as part of C&S project

Can this credit be achieved if there will be no ventilation as part of the C&S project? I know the requirements for tenants to comply can be covered with a lease agreement, but the form makes you select what type of ventilation the building will have; mechanical or natural. Since there is no ventilation as part of the C&S project I cannot check either box and the form cannot be completed. Even if I use special circumstances and enter a statement the form still cannot be completed due to not checking one of these boxes. How will I be able to demonstrate compliance using the lease agreement? Or can this credit not be achieved if the C&S project doesn't have ventilation?

Would greatly appreciate input anyone may have.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Apr 05 2012 LEEDuser Moderator

Tony, I think the answer to your question, or at least the best answer available, is specific in CS Appendix 4, Case 3, in the LEED Reference Guide—you need to rely on the tenant agreement.

If you feel that you just don't have any idea how the project will be ventilated, though, then perhaps IEQc1 is not a good fit for this project. As a side note, I'm surprised that a shell can be designed and built without taking into account good design for either natural ventilation, or an assumption of mechanical.

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Tony Schafer Apr 05 2012 Guest 158 Thumbs Up

Thanks Tristan, based on your response I think the answer is that we either need to incorporate natural ventilation in the C&S project, or assume mechanical ventilation for the tenant build-outs and incorporate that requirement into the lease agreement. If we choose the mechanical ventilation option, we can check that box in the form since that is our requirement for the tenants, even though the C&S itself will not be ventilated. Does that sound right?

Also, one other question - for the case of a warehouse C&S project, would it be adequate to require the tenants to ventilate the office spaces only, and not the warehouse itself? Warehouses tend to have high infiltration through dock doors and other openings and sometimes do not have any other method of ventilation. Will LEED require that we have a means of ventilating the warehouse space other than infiltration?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Apr 05 2012 LEEDuser Moderator

Tony, that does sound right.

Regarding the warehouse, LEED pretty much relies on ASHRAE 62 for expectations in this credit. And I believe that ASHRAE 62 will have some minimum ventilation rates for a warehouse that is used as a workplace. If you want to go with natural ventilation, then I would make sure you have enough infiltration by formalizing a design for that.

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BH .
Aug 23 2011
LEEDuser Member
607 Thumbs Up

summary for mechanically ventilated spaces

So briefly (for C&S mechanically ventilated spaces):

For densly 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. we need: CO2Carbon dioxide monitors and i.e. air flow monitoring located in the outdoor intakes of each central HVAC

For non-densly occupied spaces we need: i.e. air flow monitoring located in the outdoor intakes of each central HVAC (without any CO2 monitors)

For tenant spaces : we can (but don`t have to) include future expansion for CO2 monitors.

That is the simplest solution, but I`m not sure if I`m right?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 21 2011 LEEDuser Moderator

Mostly right—you do need to required tenants through lease agreements to comply with the credit as well, so that would imply the need to provide infrastructure supporting this.

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Michael E. Edmonds-Bauer Edmonds International Nov 15 2012 LEEDuser Member 77 Thumbs Up

So, when a tenant install its own CO2Carbon dioxide monitor, is there any requirement for the alarm?

I mean, can this alarm be provided at the tenant own space, or does the C&S building's BMS need to be notified too?

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Michael Smithing Director - Green Building Advisory, Colliers International Nov 16 2012 LEEDuser Member 813 Thumbs Up

We install these regularly in CI projects. The CI credit language says that an alarm needs to sound either to the building operator OR the occupants. As I don't think the building operator will actually take action on the alarm, I make sure the monitor can make a visual alarm to the space occupants who can open the window or door.

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Adam Targowski Owner, ATsec Dec 06 2012 LEEDuser Member 577 Thumbs Up

I'm working on a C&S shopping mall project. If I understand well it's enough to install CO2Carbon dioxide sensors only in a core and shell areas (if there are 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).). We don't have to require future tenants to install CO2 sensors, is that correct?
Regarding airflow monitoring - if some tenants will install their own ventilation systems then we should require that they install airflow monitoring devices, right?

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Michael E. Edmonds-Bauer Edmonds International Dec 11 2012 LEEDuser Member 77 Thumbs Up

Hello Adam,

If I am not mistaken, from the conversation before, there is no need to "REQUIRE" the tenant by a leasing agreement to install the CO2Carbon dioxide censor, they can provide them if they want to, in order to apply for this credit in a CS building the BMS must be capable of expand to accomodate censor monitoring and to call attention to building users in case CO2 levels are exceeded.

Michael, Tristan, please correct me if I am wrong.

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Adam Targowski Owner, ATsec Dec 11 2012 LEEDuser Member 577 Thumbs Up

Thank you for your reply. Is it really required that the BMS system is capable of expansion? Isn't it enough if the sensors give visual alert to the space occupants?
Moreover, my concern is that there will be a CAV vetilation system in this shopping mall and CO2Carbon dioxide sensors won't be of much use for future tenants (since that are no windows or doors that could be opened to allow more air).

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William Wong
Jul 10 2011
Guest
498 Thumbs Up

How many CO2 sensors are required per space?

Credit requires to monitor CO2Carbon dioxide level 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).. Is there any requirements for the minimum no. of sensors per space / sq ft?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 20 2011 LEEDuser Moderator

William, there is no specific requirement for this, no.

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William Wong
Jun 09 2011
Guest
498 Thumbs Up

CO2 sensor in area designated for F&B (C&S project)

Our core and shell commecial development involves designation of one floor of the builidng for F&B and design density is higher than 25 people per 1,000 sq ft. Shall we provide CO2Carbon dioxide sensors in such spaces in our core and shell construction when project scopes don't include fitting-out of the area ?

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Susann Geithner Director of Sustainability, HSB Architects & Engineers Aug 24 2011 LEEDuser Expert 7764 Thumbs Up

You only need to have a system in place, which allows for the installation of CO2Carbon dioxide sensors and demand controlled ventilation. Just like the thermal comfort control (thermostats) for rooms you may not know yet, how this is going to be built out. So you will need for instance VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. boxes (no constant volume) with the possibility to connect to the CO2 sensors. Also the main outdoor air intake need to be monitored.

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Michael Smithing Director - Green Building Advisory, Colliers International Nov 23 2011 LEEDuser Member 813 Thumbs Up

I don't see any requirement in the credit language (for my CI project) for the CO2Carbon dioxide sensors to actively control ventilation levels. Is this a difference between the CS and CI credits or am I missing something.

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Omar Katanani
Jun 08 2011
LEEDuser Member
5163 Thumbs Up

Typical Design CO2 Level

Dear all,

I understand that LEED doesn't require you to specify a maximum CO2Carbon dioxide level for this credit. The requirement is to monitor whatever the design CO2 level is, and make sure it doesn't vary by more than 10%.

That being said, can anyone advise of a typical CO2 design level for a Food Court area and a circulation area?

Many thanks,

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Jean Marais b.i.g. Bechtold DesignBuilder Expert Jun 08 2011 LEEDuser Member 5224 Thumbs Up

Are you sure the circulation area needs to be monitored? It's not regularly occupied space where there are people working, is it?

Usually 800-1000 ppmParts per million. are normal upper bounds. Depends on the outside air condition as well. I think the difference becomes important. I read a good article in ASHRAE Journal on this, but can't remember for sure what the numbers were. Outside normal is about 400 ppm as the standard. 600 ppm would be for offices if the outside is at 400 ppm (I think)...is there not something in the ref guide about this?

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G B
Mar 13 2011
Guest
72 Thumbs Up

CO2 sensor issue

Hello all,
I would kindly ask for an information please.
My HVAC multizone system, looks like this. VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. 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. system (with sensible heat recovery, no mixing) + Fan Coil Units (FCU). Primary cooling/heating is achieved via FCU (eliminates sensible cooling/heating loads). Conditioned air supplied by AHU serves for ventilation purposes only and is controlled by volume control dampers (regulate airflow rates based on amount of fresh air needed for each zone). AHU is selected based on total airflow as per ASHRAE 62.1 for all zones. I am introducing 30% more fresh air than min. required by referenced standard to achieve IEQc2 (Increased ventilation). Several CO2Carbon dioxide monitors installed in densely occupied areas , sense high CO2 levels (higher than set values). It will alarm occupants and via BMS (building monitoring system) trigger appropriate corrective action (e.g. opening dampers, or AHU's external louvers) to increase outdoor fresh air delivery to the zones to eliminate high levels of CO2.

My concerns are:
1) How can HVAC system deliver more fresh air when AHU is selected based on total airflow rate as per ASHRAE 62.1. Does it mean that I have to add a safety margin e.g. 10-15% to a design flow rate to accommodate such scenario ?
How can I calculate the value of safety margin that will mitigate CO2 levels below 800ppm for example?
2) How can I deliver more air in case of constant volume systems? The air rates are fixed.
3) How to approach the problem in case of all air VAC systems (where air supplied by AHU is used to eliminate loads)?

Thanks muchly.

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Jean Marais b.i.g. Bechtold DesignBuilder Expert Jun 01 2011 LEEDuser Member 5224 Thumbs Up

CO2Carbon dioxide sensor issue

Those are indeed top notch questions.
1)

If you have automated variable volume control dampers elsewhere in the building, you could program them to turn down airflow to non-CO2 effected zones to say 50% to give you enough air to shortly "flush-out" CO2-effected zones. Remember that normally it takes a long time for CO2 to build up in a large space.

If you have only constant dampers, you could ask the manufacturer if you could increase the max fan speeds for a short flush-out period on the main 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..

How can I calculate the value of safety margin that will mitigate CO2 levels below 800ppm for example? ---Luckily LEED doesn't ask you to calculate this. There are simulation programs like CONTAM and EnergyPlus that can do this with considerable effort, but I would go on the fact that the AHU / system in place is only capable of delivering an absolute maximum of X and would not over design a system for a scenario that is likely never to happen. That's what smoke exhaust systems are for. The CO2 sensor credit is about alerting to a problem, more than over designing a AHU to fight smoke.

2)see the second part of 1)

3)If you do the american thing and try and combat loads with air from the AHU, you usually end up with huge ducts transporting a mixture of fresh and the much larger volume of recirculated air, meaning the AHU is large enough for transporting 800% the required fresh air if it had to run on 100% outdoor air...so basically you'll tell the system to ignore space loads during the "flush period" and just run as much outdoor air as you can suck in through the ducts to outside.

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Omar Katanani
Sep 14 2010
LEEDuser Member
5163 Thumbs Up

Do these requirements apply to tenanted areas too ?

Hello,

I was wondering if the design team must specify CO2Carbon dioxide sensor and outdoor air flow measurement devices for tenanted areas too ? Or do these requirements only target C&S occupied areas ?

Our project is a Core & Shell office and it is not known which areas will serve as conference room, private offices or open plan office. It will all depend on the future tenant layout.

Many thanks,

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Allison Zuchman Green Building Consultant, Fore Solutions Sep 17 2010 Guest 486 Thumbs Up

CO2Carbon dioxide sensors and outdoor air flow monitors are not required in tenant spaces that are not within this scope of work. However the base building mechanical system must be designed so that these sensors can be added during the tenant fit-out. It is recommended to include requirements for monitoring devices in tenant guidelines or lease agreements.

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Omar Katanani Sep 17 2010 LEEDuser Member 5163 Thumbs Up

Hi Allison,

Many thanks for the reply.

We will definitely include the requirement in Tenant Guidelines, but could we get the point even if all main occupied areas are tenanted?

The only place I could think of that would be considered "occupied" and C&S is the entrance lobby. Would that be enough to get the credit ?

Thanks,

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Allison Zuchman Green Building Consultant, Fore Solutions Sep 21 2010 Guest 486 Thumbs Up

Sorry for not getting back to you sooner. I would think that you can get the credit with your scenario above, though I am not absolutely positive. I know in CS 2.0 you could get the credit by obligating all tenants through lease agreements to follow the credit requirements, but I have not yet submitted a CS 2009 project. I did a little searching and it is a bit vague whether that path is acceptable for CS 2009. I would think so, but maybe submit 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 to be sure?

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Omar Katanani Jan 12 2011 LEEDuser Member 5163 Thumbs Up

Hi Allison,

So I followed your advice and submitted this as 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. The following is the answer I got from the USGBC:

"The applicant is requesting clarification regarding compliance with the credit for spaces with tenant fit out. The applicant notes that it is not yet clear which spaces will be densely occupied. Details for Core and Shell projects with tenant fit out spaces can b e found under the Core and Shell Appendix 4 of the LEED Reference Guide for Green Building Design and Construction. Outdoor air flow measurement devices are required for all mechanical ventilation systems serving the Core & Shell project unless the Core and Shell scope of work includes installing CO2Carbon dioxide monitoring for each regularly occupied area in the space. Per the LEED Design and Construction Reference Guide, project teams may want to design control systems with the capability for future expansion to allow CO2 monitoring 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).; however, this is not required for compliance with this credit under the LEED Core & Shell rating system.
--------------------

Note the following in their answer: "Outdoor air flow measurement devices are required for all mechanical ventilation systems serving the Core & Shell project unless the Core and Shell scope of work includes installing CO2 monitoring for each regularly occupied area in the space". In my opinion, this means that we only need to install the CO2 sensors and Outdoor measurement devices in C&S areas only. They do not mention the need to have a tenant lease agreement requiring tenants to install CO2 sensors and outdoor measurements devices. I welcome your comments on this.

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Val Fan May 24 2011 Guest 26 Thumbs Up

When it is mentioned: "Outdoor air flow measurement devices are required for all mechanical ventilation systems serving the Core & Shell project", does it mean we shall install these devices 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. or each end-user devices (such as Chilled beams) ? Thanks

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Petr Lhoták Technologist, Sustainability Consultant, Skanska Czech Republic Oct 27 2011 Guest 1050 Thumbs Up

Val,
you only need to install those devices for AHUs providing at least 20% air supply to nondensely 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..

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Lucie Sancova May 31 2012 LEEDuser Member 54 Thumbs Up

Hi George,

in our project all the mechanical ventilation systems serving tenant office spaces are equipped with the outdoor air flow measurement devices. In tenant sales and lease agreement there will be requirement that 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). (meeting rooms and open offices) the tenants must install CO2Carbon dioxide sensors. We have an office building with 5 floors of tenant office spaces with the same floor area and the final layout is not known. Is it sufficient to provide representative floor plan for one - the most probable tenant layout with the CO2 sensors location or is it necessary to provide plans of all of the floors to show compliance?

Thanks!

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Omar Katanani
Aug 11 2010
LEEDuser Member
5163 Thumbs Up

CO2 sensors in non-densely occupied spaces

Hi there,

The design team of a project we are working on, would like to install CO2Carbon dioxide sensors in every occupied area, including the non densely occupied. Will this satisfy the credit requirements? In other words can CO2 sensors replace outdoor air rate monitors in Non densely occupied areas?

We realise the above would be very costly, but it does not seem to be a particular issue in this case.

Many thanks

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Allison Zuchman Green Building Consultant, Fore Solutions Aug 11 2010 Guest 486 Thumbs Up

CO2Carbon dioxide monitors cannot replace outdoor air monitors. CO2 sensors do not provide the same benefit in 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)." as they do in densely occupied spaces. CO2 sensors measure only CO2 generated by human occupants and they are typically not a good way to indicate indoor air quality in non-densely occupied spaces.

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Jose Salinas Mr, Poch & Associates Aug 27 2010 LEEDuser Member 550 Thumbs Up

I have the same problem: the project is a Comercial Interiors on three floors of a non-LEED building.
The project is reusing the central HVAC form the building which comply with more than a 30% rate of Outdoor Air.
The air flow is constant. The HVAC expert installed CO2Carbon dioxide sensors all over the place with the folowing rationale:
CO2 sensor would indicate the air quality while the flow sensors would measure the air flow, but they do not assure the air quality of that flow. This apparently will jeopardize this credit, however other technicians agree with the criteria. Really, there are no "special circumstances" in this case?
Thank you

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Allison Zuchman Green Building Consultant, Fore Solutions Aug 31 2010 Guest 486 Thumbs Up

It sounds like you have both outdoor airflow measurement devices and CO2Carbon dioxide sensors. Is that correct? If so, CO2 sensors are redundant from a LEED perspective if they are also installed in the non 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).. Though your project will meet the LEED criteria if both are installed.

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Jose Salinas Mr, Poch & Associates Aug 31 2010 LEEDuser Member 550 Thumbs Up

Allison, thanks for your answer, but no, unfortunately I have only a lot of CO2Carbon dioxide sensors. The HVAC engineer discarded the option of flow meters because of the constant flow from the AHUs and the 30%+ calculated rate of outdoor air. he says that the flow meter is unnecesary because the flow is assured at a constant rate, and the flowmeter will not ensure the "quality" of this flow.

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Allison Zuchman Green Building Consultant, Fore Solutions Sep 01 2010 Guest 486 Thumbs Up

CO2Carbon dioxide sensors cannot replace outdoor air flow monitors in 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).". And per the July 2010 LEED addenda, it appears that both CO2 sensors and outdoor air flow monitors are required in densely occupied spaces. I can understand your rationale, and we have had an ongoing conversation in our office about this issue, but I think that the value of the outdoor air flow monitors is to confirm that the system is operating as designed and to problem solve later on if any maintenance issues arise.

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