NC-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.

  • 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.

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

  • 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.

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 New Construction and Major Renovations

    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.

    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

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.

ASHRAE 62.1-2007: Outdoor Airflow Monitoring Devices.

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

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.

LEED Online Forms: NC-2009 IEQ

The following links take you to the public, informational versions of the dynamic LEED Online forms for each NC-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):

Version 3 forms:

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."

Design Submittal

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

135 Comments

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Amanda Thomas Associate Gensler
Jan 21 2013
LEEDuser Member

CO2 sensors in areas smaller than 150 sf

In the LEED EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. reference guide, spaces smaller than 150 sf do not have to provide CO2Carbon dioxide sensors, according to California Mechanical Code Title 24. It is my understanding that this is only applicable to LEED EBOM, not LEED NC. I've seen discussions under this forum that question whether it can be applied to LEED NC, but no resolution so far. Does anyone have more information? Thanks!

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John McFarland Director of Operations, WorkingBuildings, LLC Jan 21 2013 LEEDuser Expert 265 Thumbs Up

Hi Amanda,
I don't think you can exempt spaces smaller than 150sf from the CO2Carbon dioxide sensor requirement in LEED-NC. The LEED-NC credit is written very differently than the LEED-EB credit. The LEED-EB credit limits the requirements based what the system is serving (either predominantly 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)." or densely occupied spaces). The LEED-NC credit applies to both the individuals spaces ("Monitor CO2 concentrations within ALL densely occupied spaces") and systems ("Provide a direct outdoor airflow measurement device...for mechanical ventilation systems where 20% or more of the design supply airflow serves nondensely occupied spaces"). So, in short, you must install a CO2 sensor in each space deemed to be densely occupied, no matter how small. Hope this helps clarify things. Good luck!

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Thomas Hellmann Director of Architecture Hixson
Dec 20 2012
LEEDuser Member
31 Thumbs Up

Table IEQc1-2 Outdoor Air Ventilation Rate

According to IEQc1, I am to complete table IEQc1-2 for all systems where 20% or more of the design supply airflow serves non-densely-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.. In my specific circumstance, I have 5 systems each with multiple zones. I have both densely and non-densely occupied zones with all but one system, and all 5 systems meet the 20% requirement.

My question is this: Do I need a line item for each non-densely populated zone in the table? i.e. RTU-1 will appear for 5 zones? Then would I do the same for RTU-2, etc?

Or can I create one line item for each system and simply list the entire outside air intake of that unit?

The reason I ask is because we are monitoring the outdoor air intake at each roof top unit, and not at each individual fan-powered supply box. We have also used the MZ calculation to size our roof top units, so it's not simple to determine our design outdoor air intake flow for each individual zone.

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Helena Larsson Environmental Certifications Engineer, Skanska Sweden Dec 21 2012 LEEDuser Member 44 Thumbs Up

Hi Thomas,
In the IEQc1 forms that I have filled in it has been important that the IEQc1-2 table (non-densely occupied space) is demonstrated in correspondence with the IEQp1 form zoning. If you have filled in each floor etc or each space individually in IEQp1 then I would most likely do the same in IEQc1-2. However, I know others have filled in this table not being as specific and still been eligble for credit compliance I.e. AHU1 floor 1, AHU1 floor 2 and so on. It would be interesting to see what your outcome is once you decide what to do so post it on here if possible. Personally I have chosen to fill in each AHU system and each zone individually and then taken the OA values directly from the IEQp1 form where they are generated automatically. You should be able to see a generated OA flow for each zone in the 62MZ calc as well.
Good luck and happy holidays!

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Devani PERERA Green Building Consultant ELAN
Nov 26 2012
LEEDuser Member
99 Thumbs Up

Types of alerts for OA monitoring

Until now, I have only seen monitoring systems connected to a BMS that generates an alert to the Facility Manager.
One of my clients is however asking if this alert could be generated by a LED or audio device located on 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. itself (on the roof). Although this does not seem reasonable as the FM would need to be on the roof to hear or see the alert, it is not clearly specified in the reference guide that such a solution is not acceptable (from a certain perspective, it is a visible or audible alert).

What other types of alerts could be accepted for OA monitoring if there is no BMS for the project?

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BR+A LEED Nov 26 2012 LEEDuser Member 28 Thumbs Up

The spefic language for the credit is "Configure all monitoring equipment to generate an alarm when the airflow values or carbon dioxide (CO2Carbon dioxide) 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." Therefore I would not think that a device located on 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. itself would meet the credit. Unless the LED or audio device was located in the space, so that the occupants where made aware.

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Barbara McCrary Mechanical Engineer, PE, LEED AP BD&C HHB Engineers, P.C., Prattville, AL
Oct 18 2012
LEEDuser Member
625 Thumbs Up

Requirement for CO2 sensor and OA measurement device

I found a thread from 2011 discussing the Addendas released 5/9/11 removing the footnote that was previously changed under Addenda reliease 9/19/10. Can someone set me straight if i'm not interpreting the 5/9/11 addenda correctly? I interpret the new requirement as: Case 1) If I have a system that serves only 1 space that is densely occupied, the only requriement of this credit is a CO2Carbon dioxide sensor. An OA measurement device is not required. Case 2) System that serves 20% or more 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 has one densely occupied conference room. I will need to provide a CO2 sensor for the Conference room AND an OA measurement device on the system, since i'm serving 20% or more densely occupied spaces. Thanks!

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Andrew Mitchell Mechanical Engineer / LEED Coordination Manager, Moses & Associates Oct 18 2012 LEEDuser Expert 623 Thumbs Up

Barbara, you are correct for both cases. Just one note; remember that the 20% refers to 20% of the supply airflow serving 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).". It does not refer to 20% of the floor area.

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Vamshi Gooje Associate Thornton Tomasetti Fore Solutions
Oct 02 2012
LEEDuser Member
3 Thumbs Up

OA air flow monitoring

At the beginning of this page, Option 1, Case 2 (for 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).") specifically indicates that the airflow monitors are required in each space to measure against the design rate, as defined by ASHRAE 62.1-2007. My interpretation of this credit requirement was that the monitors need to be installed at the outdoor intake of the ventilation system and not in the duct to each space. For a non-100% OA system serving multiple zones (non-densely occupied spaces), the monitors in each space cannot measure ventilation air alone (it's mixed air) and will not meet the credit intent. Any thoughts?

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Dylan Connelly Mechanical Engineer, Integral Group Oct 02 2012 LEEDuser Expert 3002 Thumbs Up

Vamshi,
You are correct and I've asked for the bird's eye view image to be updated.
The credit language says:
“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 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..”
The Birds Eye View image says "space" it should say "system." I’d recommend revising the sentence to say:
“At least 20% of system’s design airflow serves not densely occupied spaces”
Then underneath that replace the statement with:
“Install outdoor airflow monitors to measure the minimum outdoor air rate of the mechanical ventilation system”

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Tatiana Machado
Sep 14 2012
Guest
10 Thumbs Up

CO2 sensors in mechanically and naturally ventilated spaces?

I have a non-densely occupied space with a mechanical ventilation system and with operable windows (natural ventilation system).
According to the diagram above: all natural ventilated spaces and only densely occupied mechanical ventilated spaces require CO2Carbon dioxide sensors.
What does this space require?

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Dylan Connelly Mechanical Engineer, Integral Group Sep 14 2012 LEEDuser Expert 3002 Thumbs Up

Credit Language: "Monitor CO2Carbon dioxide concentrations within all naturally ventilated spaces."
Did you mean that you have mechanical conditioning and natural ventilation? Or do you have mix mode in this space with natural ventilation during parts of the year and mechanical ventilation during other parts of the year.

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Ante Vulin Sustainability Manager, YR&G Sep 14 2012 LEEDuser Expert 354 Thumbs Up

CO2Carbon dioxide sensors will be required if there are times during normal operation when the space is occupied and the mechanical ventilation system is not functioning (i.e. the natural-ventilated mode). If the mechanical ventilation system will operate consistently whenever the room is occupied, then no CO2 sensor is required.

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Jiri Dobias
Sep 04 2012
LEEDuser Member
452 Thumbs Up

Retail and CO2 sensors

Do we have to install CO2Carbon dioxide sensor in each retail unit if they will be considered as densely occupied areas according LEED definition? There will be only one employee in each unit but several customers.
Thank you for any suggestions.

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Andrew Mitchell Mechanical Engineer / LEED Coordination Manager, Moses & Associates Sep 04 2012 LEEDuser Expert 623 Thumbs Up

Jiri, For this credit I always use the same occupant load that I use to determine minimum OA flows in accordance with ASHRAE 62.1 - 2007. See the link below to the ASHRAE Addendum page. Download Addenda g, r & t to ASHRAE 62.1 - 2007. In adendum t paragraph 6.2.1 is altered and a new paragraph 6.2.1.1 is added. 6.2.1.1 defines your design zone population as the "largest (peak) number of people expected to occupy the ventilation zone during typical usage." If your peak load is more than 25 people per 1,000 sf then CO2Carbon dioxide monitors will be required to comply with this credit.

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Maura Adams Environmental Stewardship Manager
Aug 28 2012
Guest
1636 Thumbs Up

CO2 sensors in return ductwork?

The CO2Carbon dioxide sensors for this science building are in the return ductwork, not 3-6' from the floor. I'm telling the team that this is clearly not in compliance, but the Honeywell rep insists otherwise. He writes: "Most schools do not have the capability to utilize return air. The location of the CO2 sensor at your building provides a better representative reading in all areas. This sensor location has been approved on all of our LEED installations to date." Any thoughts on this?

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Dylan Connelly Mechanical Engineer, Integral Group Aug 29 2012 LEEDuser Expert 3002 Thumbs Up

C02 Sensors in the return ductwork can be very informative to your system's operation when serving large 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). with a central return duct. However, it does not meet the requirements (of this credit) for CO2Carbon dioxide sensors in each densely occupied space.

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Sonrisa Lucero Owner / Energy Engineer / Sustainability Consultant, Sustainnovations, LLC Feb 27 2013 LEEDuser Member 858 Thumbs Up

Maura, what did you end up submitting for this credit? Have you received your review back and did it pass with the sensors in the return air ducts?
Thanks!

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chris buntine
Aug 22 2012
LEEDuser Member
20 Thumbs Up

Placement of CO2 sensors in a stadium bowl?

A sports stadium bowl exceeds the occupant density threshold and therefore would require CO2Carbon dioxide sensors. Placing the sensors between 3 and 6 feet above the floor doesn't make sense in a high volume space like this. How do we go about meeting this requirement?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Aug 31 2012 LEEDuser Moderator

Chris, I would discuss it with your mechanical engineer and have them make a sensible proposal that addresses CO2Carbon dioxide concentrations 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 62.1–2007). Then, present that to GBCI with a narrative explaining how it does the best possible job of meeting the credit intent and requirements. Then, hope for the best.

Sorry to not be of more help on the technical details, but it seems like a question for an engineer.

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Victor Avedano Principal JALRW Eng. Group Inc.
Aug 16 2012
LEEDuser Member
102 Thumbs Up

CO2 sensor alarm when conditions vary 10%

The credit template requires the CO2Carbon dioxide sensors to be programmed to generate an alarm when the conditions vary by 10% or more from the design value. Currently we are designing a facility 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. and 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 that requires 4 rooms to have CO2 sensors, but wouldnt this requirement only apply to constant volume systems since the ventilation of the rooms would depend on the CO2 sensors therefore it would most of the time not be at full occupancy and most of the time below the minimum outdoor air required?

Thanks

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BR+A LEED Aug 17 2012 LEEDuser Member 28 Thumbs Up

According to the credit language the CO2Carbon dioxide sensor only requires an alarm either from the building automation
system to the building operator, or as a visual or audible alert to the building occupants. It does not have to be tied to the HVAC system.

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Helena Larsson Environmental Certifications Engineer Skanska Sweden
Aug 07 2012
LEEDuser Member
44 Thumbs Up

CO2 sensors applicable to non regularly occupied space?

I have a question in regards to non-regularly occupied lunch/breakrooms. Default occupancy density for break rooms/ lunch rooms is 25 / 1000sf but break rooms are also considered non regularly occupied space. Does this mean that these type of rooms are exempt from the CO2Carbon dioxide sensor requirement in IEQc1?

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Yetsuh Frank Director, YR&G sustainability consulting, education and analysis Aug 07 2012 LEEDuser Expert 281 Thumbs Up

That's correct, no CO2Carbon dioxide sensors in non regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building. like lunch rooms. As noted in the LEEDuser checklist for this credit, CO2 sensors are actually a poor air quality measurement tool in places that are not densely occupied because they are designed to measure CO2 generated by humans. Better to ensure delivery of fresh air through direct monitoring of OA.

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Dylan Connelly Mechanical Engineer, Integral Group Aug 08 2012 LEEDuser Expert 3002 Thumbs Up

Helena,
I am not so sure that break rooms/lunch rooms are excluded from this credit (or even should be considered non-regularly occupied).
The credit language does not specifically say "regularly occupied" anywhere, but rather says "Monitor CO2Carbon dioxide 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).."
IMO you would be pushing your luck on this credit if you don't provide CO2 sensors in break rooms/lunch rooms.
Yetsuh,
Yes, CO2 sensors in places that are not densely occupied are not required, but the question was regarding densely occupied spaces that are only occasionally occupied.
The CO2 sensors used in densely occupied spaces for this credit need only generate an alarm and not necessarily be used to dictate the amount of OA.

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Yetsuh Frank Director, YR&G sustainability consulting, education and analysis Aug 08 2012 LEEDuser Expert 281 Thumbs Up

I happily defer to the engineer among us. We have excluded these types of spaces previously without a problem but, per your reading, it is probably best for Helena not to push her luck.

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Dylan Connelly Mechanical Engineer, Integral Group Aug 08 2012 LEEDuser Expert 3002 Thumbs Up

All experiences and opinions are welcome!
I think this regularly occupied space business could use a clarification from the LEED folks. We wouldn't exclude break rooms/ lunch rooms from our Ventilation Calcs, but it does seem to not fit into the definition of:
"Regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building. are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building."

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Helena Larsson Environmental Certifications Engineer, Skanska Sweden Aug 09 2012 LEEDuser Member 44 Thumbs Up

Yetsuh and Dylan, thank you for your thoughts on this subject!
If we were early in the design phase I would definitely not take any chance at this but as the building is already in place we might consider installing the type of sensor that doesn't regulate OA but only generates some type of alarm. In the IEQ space Matrix that you can find on usgbc's webside, all types of spaces are presented and defined whether they should be considered regularly occupied or not, pretty useful when filling out the PIf3 template etc. According to this sheet, break rooms are not considered regularly occupied. Again, thank you both for your input!

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Hernando Miranda Owner, Soltierra LLC Sep 24 2012 Guest 2776 Thumbs Up

To be safe use the one-hour rule, intended for schools, but applicable to any LEED project.

LEED 2009 BD+C Reference Guide
> IEQ Overview
> Compliant Space Types for Indoor Environmental Quality Credits
> Other Regularly Occupied SpacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building.

"This category includes all nonlearning spaces that are used by occupants for 1 or more hours per day to perform work-related activities: ...."

Included in the list above are: kitchen and staff lounge.

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John McFarland Director of Operations, WorkingBuildings, LLC Oct 02 2012 LEEDuser Expert 265 Thumbs Up

Hi everyone,
I think Dylan is exactly correct that the credit makes no exception for densely occupied areas if they are not regularly occupied. In fact, these are the best candidates for monitoring CO2Carbon dioxide in a demand controlled ventilation strategy. Since the design outdoor air is only needed when the space is fully occupied, there is a likely a huge opportunity to save energy while ensuring adequate ventilation when the space is either unoccupied or partially occupied. Care should be taken in determining the proper CO2 setpoint (note, it's likely not 1000 ppmParts per million. or even 700 ppm above ambient - refer to Appendix C of ASHRAE 62.1-2007). Also remember that you cannot reduce the ventilation rate below the "building" component (Ra in Table 6-1) except when the air handling system is in the "unoccupied" mode. Other considerations include using accurate CO2 sensors, calibrating them at regular intervals and making sure the modulating outdoor air dampers are well-maintained.

Perhaps the irony of this credit is 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 are regularly occupied at design rates, then Yetsuh is absolutely correct that the best means of ensuring a ventilation rate that meets 62.1 is to directly measure the outdoor airflow and compare the measurement against the design setpoint. A CO2 sensor in this case really doesn't help you much, but that's not how the credit requirement is worded. Maybe we can change that in the next version.

So in summary, stick to your plan and put the CO2 sensors in the lunch/break rooms. Consider using demand controlled ventilation (DCV) strategies to save energy. If done correctly, we can have our cake (good 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.) and eat it too (save energy)!

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Rudolph Carneiro HVAC consultant Sustentech
Jun 21 2012
Guest
158 Thumbs Up

CO2 sensors in naturally ventilated spaces

The footnote at the bottom of the page states that cO2Carbon dioxide sensors are required in densely ocupied spaces. Is it correct to assume, therefore, that non-densely ocupied spaces dont require CO2 sensors?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jun 21 2012 LEEDuser Moderator

Rudolph, that's correct. I'd recommend reviewing the diagram and other info above for more detail on what's required in each space type.

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Rudolph Carneiro HVAC consultant, Sustentech Jun 21 2012 Guest 158 Thumbs Up

The diagram at the top of this page seems to be incorrect then. Should there not be a box below the "naturally ventilated" option stating that a naturally ventilated space needs to be densely occupied in order for CO2Carbon dioxide sensors to be required?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Jun 21 2012 LEEDuser Moderator

Rudolph, checking against the credit language (also above), the diagram is correct about CO2Carbon dioxide sensors being required for all naturally ventilated spaces.

I apologize, in my original response I assumed you were asking about mechanical ventilation.

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susan eguia
Jun 11 2012
Guest
937 Thumbs Up

IEQc1_Densely and Nondensely Occupied Spaces

Hi,

How do we define nondensely spaces? To satisfy LEED requirements for this credit, do we really need to install CO2Carbon dioxide sensors for densely and OA Measurement Device for nondensely? What is the difference between CO2 sensors and OA measurement device? Since nondensely is less than 25 people or non regular occupied space, why do we need the OA device? What are they trying to monitor.

Any inputs on this area is highly appreciated.

Regards,
Susan

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Andrew Mitchell Mechanical Engineer / LEED Coordination Manager, Moses & Associates Jun 12 2012 LEEDuser Expert 623 Thumbs Up

Susan, here are some responses to your questions. I hope they help:

1. A non-densely occupied space is any space with a density of less than 25 ppl/1,000 sf. Divide the space area by the number of people who regularly occupy the space and if that number is more than 40 (sf/p) then it is a 'non-densely occupied space'.

2. Yes we do need both CO2Carbon dioxide for densely and OA measurement for 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).".

3. A CO2 sensor is mounted in the space and measures the CO2 content in the air (in ppmParts per million.). An OA measurement device is a flow measuring station in the OA duct/intake of the system serving one or more zones. There are other alternatives for certain applications that can be found in the LEED Interpretations database but typically a monitoring station is used.

I hope that helps. Remember that for non-dense spaces the intent is to measure the ventilation air to the system to make sure it stays at design airflow.

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susan eguia Jun 12 2012 Guest 937 Thumbs Up

Hi Andrew,

Thanks for responses. Just a follow-up question please to understand o of identifying densely and non-densely spaces:

1. For densely occupied space e.g. main entry lobbies with 3,252 SF, should i divide it by 25 and get 130? Or apply 25 ppl/1,000 sf. i have 75 ppl. Is this correct?

2. For non-densely, e.g. breakrooms (130 sf), i divided it by 40sf = 3 ppl. Is it considered non-densely space?

3. What do you mean by " for mechanical ventilation system where 20% or more of the design supply airflow serves 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."? Does it mean if i have 3, 280 CFM Design OA intake flow, and 20% of it (656 cfm) is non-densely, then it requires direct outdoor airflow measurement device?

Pls. clarify.

thanks,
susan

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Andrew Mitchell Mechanical Engineer / LEED Coordination Manager, Moses & Associates Jun 13 2012 LEEDuser Expert 623 Thumbs Up

Susan, I think for the first two questions you might be thinking about it backwards. Don't try to figure out the space population based on whether or not you think it should be densely populated. You should have the area and population based on the plans and discussions with the owner/architect. Use those two variables to then figure out if it's densely populated or not. As for number 3, you are correct.

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susan eguia Jun 13 2012 Guest 937 Thumbs Up

Andrew,

those values are based on the plans, i just want to make sure if my approach/understanding to identify densely and non-densely is correct.

thanks,
susan

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susan eguia Jul 05 2012 Guest 937 Thumbs Up

Hi,

I have question for the following:
1. In reference to above diagram, under OPTION 1 - Mechanical Ventialtion, we can satisfy either/Or for Case 1 or Case 2?
2. Or we need to satisfy both requirements for Case 1 and 2?
3. What do you mean by " for mechanical ventilation system where 20% or more of the design supply airflow serves 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."? Does it mean if i have 3, 280 CFM Design OA intake flow, and 20% of it (656 cfm) is non-densely, then it requires direct outdoor airflow measurement device? Then, if its less than 20% (120 CFM) for non-densely we don't need OA measurement device and explain it to narrative?

Appreciate clarification of requirement for this credit.

Regards,
Susan

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susan eguia Jul 10 2012 Guest 937 Thumbs Up

Hi,

Can someone help me on this. If my non-densely space is less than 20% design OA intake flow, we don't need to provide OA measurement device? Likewise, my project consists of densely space only and we will provide narrative to support this.

Please advice, just want to clarify if both CO2Carbon dioxide sensors and OA measurement device are really needed. What is the guideline to determine that CO2 sensors and/or OA measurement device is needed.

Appreciate quick assistance.

Regards,
Susan

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Andrew Mitchell Mechanical Engineer / LEED Coordination Manager, Moses & Associates Jul 10 2012 LEEDuser Expert 623 Thumbs Up

Susan, in order for you to be exempt from providing a monitoring station your non-dense space supply airflow will have to be less than 20% of the total airflow. You do not calculate the 20% as if it were only the fraction of required OA. For example, if you have a 10,000 CFM air handler and less than 2,000 CFM serves non-dense space then you do not need a measurement device. This is regardless of the required OA flow to the non-dense space. If you are still confused then please reply with actual design numbers and it will be apparent which situation you fall under.

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susan eguia Jul 10 2012 Guest 937 Thumbs Up

Andrew, so it's not always BOTH (CO2Carbon dioxide and OA) to satisfy the requirements? It really depends what is applicable to project as long as it was explained in narrative, right?

thanks for clarifying the requirements. This is so confusing.

Regards,
Susan

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susan eguia Jul 10 2012 Guest 937 Thumbs Up

Andrew, another thing, is there any references or statement that i could use as a reference to justify that my project doesn't require OA for my narrative?

thanks, again.

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Andrew Mitchell Mechanical Engineer / LEED Coordination Manager, Moses & Associates Jul 10 2012 LEEDuser Expert 623 Thumbs Up

Susan, yes to the first question. As for the second, I never said that anything we discussed justifies not using OA, just not monitoring the OA. If you want to justify not monitoring the OA just quote the verbiage directly from the LEED Reference Guide.

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susan eguia Jul 10 2012 Guest 937 Thumbs Up

Andrew, sorry Im still confused. Could you please explain this statement " Provide a direct OA measurement device capable of measuring the minimum OA intake flow with an accuracy of +/- 15% of the design minimum outdoor air rate, as defined by ASHRAE 62.1-2007 for mechanical ventilation system where 20% or more of the design supply airflow serves 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.".

Does it mean if i have 3, 800 CFM Design OA intake flow, and 20% of it (760 cfm) is non-densely, then it requires direct OA Measurement device, right? What if we've only identified less than 20% (155 CFM) for non-densely space, do we still need to provide OA measurement device?

This is what makes us confused. If we need to provide or NOT.

thanks,
Susan

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susan eguia Jul 10 2012 Guest 937 Thumbs Up

Andrew, if we decided not to use the monitoring OA device due to less than 20% design OA, do we still need to input this to the template? if so, then USGBC will still require us to provide this device or we can just explain it to our narrative? Any suggestion please. thanks - susan

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Andrew Mitchell Mechanical Engineer / LEED Coordination Manager, Moses & Associates Jul 11 2012 LEEDuser Expert 623 Thumbs Up

Susan, I think you are making this much more complicated than it is. It's very simple. Follow this process for your situation:
1. Add up the total SUPPLY airflow to all 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)." (for each system).
2. Divide that flow by the total system flow (for each system).
3. If your fraction is less than 0.20 then you don't need to do anything further. If it is 0.20 or higher go to the next step.
4. Provide an OA monitoring system capable of measuring the OA flow (this is the first time you will be looking at OA flow).

It's that simple. If you are still confused then please click on my name and go to my website to get my contact info. Call me at my office and I will be more than happy to explain this to you.

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susan eguia Jul 11 2012 Guest 937 Thumbs Up

Andrew, are you saying that we still need to provide OA measurement device for non-densely eventhough we have less than 20% design supply airflow? By the way, we have CO2Carbon dioxide sensor for densely spaces. My only concern is for non-densely. I will try to call, i think we have time difference since Im from LA.

Once again thanks for being patient with my never ending question.

susan

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Andrew Mitchell Mechanical Engineer / LEED Coordination Manager, Moses & Associates Jul 11 2012 LEEDuser Expert 623 Thumbs Up

Susan, I don't know if you need it or not because I don't know your actual design numbers. Call my office at 10:15 PST and ask for me.

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susan eguia Jul 11 2012 Guest 937 Thumbs Up

Our total design supply airflow for all system is 3,955 cfm and for non-densely is 155 cfm only. So, it's less than 20% which means no need to provide OA measurement device for non-densely spaces.

thanks,
susan

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Regina Ng
May 29 2012
LEEDuser Member
677 Thumbs Up

Airflow Monitoring Devices

The contractor has proposed to use 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. box as a airflow monitoring sensor. Is this acceptable to USGBC?

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Dylan Connelly Mechanical Engineer, Integral Group Jun 05 2012 LEEDuser Expert 3002 Thumbs Up

If the 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. box has an airflow sensor (which many of them do), then it would be acceptable. Typically a VAV box will incur a higher pressure drop and be noisier then a separate airflow sensor, so take that into account. Also, each type of airflow sensor has a limited airflow range that they work in, so be sure to properly size the sensor/VAV box for the maximum and minimum airflows serving your spaces.

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Emil Andersson Green Certification Coordinator Skanska Sweden
Apr 18 2012
LEEDuser Member
210 Thumbs Up

Heat-triggered sensors vs. CO2-sensors

For a system with 100 % outside air, would it be possible to fulfill the credit intent by the utilization of heat triggered sensors? So instead of adjusting the intake air flow in 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). using CO2Carbon dioxide the ventilation rates are adjusted when the temperature from the users reach a trigger level.

The system would of course be connected to the heating/cooling system to avoid system interference effects.

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Samantha Harrell LEED Project Reviewer certificate holder Apr 18 2012 Guest 1412 Thumbs Up

Hi Emil, this approach would work for CI v2009 EAc1.3 to meet the requirement to install active controls capable of sensing space use and modulating the HVAC system in response to space demand. However, the requirements for this credit are pretty stringent regarding CO2Carbon dioxide sensors.

You could request in your submittal 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. 5731 be considered for alternative compliance (the Applicability tab indicates that it hasn't been considered for 2009 projects yet, but also that it hasn't been marked as 'not applicable'). This LI allows an alternative to providing CO2 sensors in areas where 100% outdoor air is provided: "The primary intent of the credit is to provide indoor air quality monitoring to sustain long-term occupant health. Your project's HVAC system is intended to provide the maximum outside air volume, but would require some instrumentation to report on the resulting 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. conditions to capture the point. CO2 sensors per se may not be required, but a monitoring system for the lab spaces should provide feedback in a form that affords operational adjustments. By providing a monitoring system that can give feedback on the space ventilation performance, operational adjustments (to outside air volumes, air changes, mixing boxes, distribution etc., either automatic or manual) can be made to correct problems."

A project-specific 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 may be the best option.

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Andrew Mitchell Mechanical Engineer / LEED Coordination Manager, Moses & Associates Apr 19 2012 LEEDuser Expert 623 Thumbs Up

Emil, it sounds like you are proposing utilization of a 100% OA multizone 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. system in lieu of monitoring CO2Carbon dioxide. Modulating space airflow based on temperature is a good idea and is very common but it does not replace CO2 monitoring. I do believe you will need to provide CO2 sensors to achieve this credit. Furthermore, there is no requirement that the ventilation rate must be changed in response to the space CO2 level, only that an alarm is generated if it is 10% low or more. I hope that helps. Also, just as an aside, if you have non-densley 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 are using a 100% OA VAV system you can use the VAV flow rings to monitor the ventilation air flow and simply program the alarms. That will save money on purchasing a system total AMS.

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Guillermo T. Adamo Architect Sursolar
Apr 11 2012
Guest
461 Thumbs Up

CO2 sensor in kitchen & others

Hi, we are working in a Gas station with three different type of spaces.

1) Individual offices with one or two employees, naturally ventilated. For this spaces we will install CO2Carbon dioxide sensors with a audible alarm so users could regulate windows. This comply with credit intent?

2) The minimarket and cafeteria areas 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). mechanically ventilated. The HVAC equipment is a heat pumpA type of heating and/or cooling equipment that draws heat into a building from outside and, during the cooling season, ejects heat from the building to the outside. Heat pumps are vapor-compression refrigeration systems whose indoor/outdoor coils are used reversibly as condensers or evaporators, depending on the need for heating or cooling. In the 2003 CBECS, specific information was collected on whether the heat pump system was a packaged unit, residential-type split system, or individual room heat pump, and whether the heat pump was air source, ground source, or water source. rooftop. For these spaces we will install the same CO2 sensors from the offices, that will generate an audible alarm but without interfering in rooftop´s outdoor air flow quantity. Is this acceptable? Or we should have an automatic system that regulates outdoor air flow ir order to comply?

3) The kitchen is a non-densely occupied space mechanically ventilated. With several hoods that exhaust the air. Due to the type of activity, should we have CO2 sensors in the kitchen? Are we required to monitor outside air flow?

Thanks for the suggestions

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Dylan Connelly Mechanical Engineer, Integral Group Apr 12 2012 LEEDuser Expert 3002 Thumbs Up

1) Yes
2) Yes, you need a CO2Carbon dioxide sensor in each densely occupied space. You also need an outdoor airflow measurement device on your heat pumpA type of heating and/or cooling equipment that draws heat into a building from outside and, during the cooling season, ejects heat from the building to the outside. Heat pumps are vapor-compression refrigeration systems whose indoor/outdoor coils are used reversibly as condensers or evaporators, depending on the need for heating or cooling. In the 2003 CBECS, specific information was collected on whether the heat pump system was a packaged unit, residential-type split system, or individual room heat pump, and whether the heat pump was air source, ground source, or water source. with an alarm if OA drops 10% below design. You do not need an automatic system to modulate the OA in order to comply. You system does not need to react if the CO2 alarm goes off, just need the alarm.
3) You don't need a C02 sensor in the kitchen if it is not densely occupied, but you do need an outdoor airflow measurement device on your make up air unit with an alarm if OA drops 10% below design (assuming you have a make up air unit to balance out the exhaust hoods).

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Guillermo T. Adamo Architect, Sursolar Apr 25 2012 Guest 461 Thumbs Up

Hi, we've been analyzing the LEED-on line form for this credit and we realized that measurement of outdoor air flow for mechanically ventilated in 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. is not necessary. Is this correct? there is no place in the form to document this and in the LEED reference guide we just found that the only requirement for these places is to install a CO2Carbon dioxide sensor, and airflow measurment is necessary just for non-densly mechanically ventilated spaces. Is this correct?

Regards,

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Dylan Connelly Mechanical Engineer, Integral Group Apr 29 2012 LEEDuser Expert 3002 Thumbs Up

Guillermo,
You are correct. Per the credit language, you only need to measure the minimum outdoor air intake flow for mechanical ventilation systems where 20% or more of the design supply airflow serves 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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Christian Brücher LEED AP / LEED AP BD+C ARCADIS Deutschland GmbH
Mar 14 2012
LEEDuser Member
369 Thumbs Up

Only one room non-densely occupied

Hi,

following situation: We have a ventilation system which serves only 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). except one small office room for one person which is occupied perhaps 1-2 hours a day (so I would call it regularly occupied). Do we really need to install a direct outdoor airflow measurement device due to the one single office room? Or would it be also ok to install a CO2Carbon dioxide-monitor there (as we will do in all the densely occupied spaces)?

Any idea?

Just found the answer myself: "where 20% or more of the design supply airflow serves nondensely occupied spaces"...

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Francisco Sanchez Arroyo hexxan
Feb 20 2012
LEEDuser Member
66 Thumbs Up

Arduino and CO2 Sensor

We are pursuing IEQc1 and we would like to use CO2Carbon dioxide sensors connected to an Open Source Arduino micro controller in order to manage the alarms, interface with other systems and publish to Pachube (http://www.pachube.com). Would it be an acceptable solution? Thanks in advance

Here you are the solution we'd like to use:

http://cdn.shopify.com/s/files/1/0019/5952/files/Senseair-Arduino.pdf

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Dylan Connelly Mechanical Engineer, Integral Group Feb 27 2012 LEEDuser Expert 3002 Thumbs Up

Francisco,
As long as you are able to meet the credit's requirements (alarms, measurement accuracy, etc), the equipment you use is up to you.

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Maria Porter Environmental Certification Engineer Skanska Sweden
Jan 25 2012
LEEDuser Member
867 Thumbs Up

Definition of densely occupied spaces

The definition 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). is “spaces with a design occupant density of 25 people or more per 1000 sf”. A conference room for example is a room that would have to have CO2Carbon dioxide monitors. But this also means that every small meeting room with only two people in it has to have a CO2 monitor too, if the density is like above. But it’s not really reasonable is it? I would say that if it’s a conference room of maybe 10 or 12 people a CO2 monitor would be good, but for just a small conversation room it’s a bit too much? Where should one draw the line? Anyone have experience on which room types should be included? Or do you put monitors in every small meeting room too? Opinions?

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Emily Catacchio Sustainability Specialist, Wight and Company Jan 25 2012 LEEDuser Moderator

Maria,

In order for a room designed for two people to require a CO2Carbon dioxide sensor it would need to be 80 sq ft or less. Just want to make sure we're clear on that point first.

If the spaces are designed as small meeting rooms and they meet the criteria above, then yes they do need CO2 sensors.

If the spaces are offices for one peron (who will regularly occupy it) and that person occationally meets with others in their office than they do not need CO2 sensors.

Basically it's about the intended use of the space.

That being said, CO2 sensors are relatively inexpensive and a good best practice.

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Dylan Connelly Mechanical Engineer, Integral Group Jan 27 2012 LEEDuser Expert 3002 Thumbs Up

Maria,
I ran into a very similar situation. See my comment on June 27th. I don't have an answer yet, as the project is still waiting for LEED review comments. However, we did do a quick energy saving ROI calc and found it would have taken over 100 years! to recoup the costs of installing all those CO2Carbon dioxide sensors. The client decided not to put in the C02 sensors.

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Maria Porter Environmental Certification Engineer, Skanska Sweden Jan 30 2012 LEEDuser Member 867 Thumbs Up

Dylan
That is very interesting! (I didn't realize that your question was about the same thing). Please do let us know how it turns out. I also have a large amount of smaller “chat-rooms”. Hasn’t anybody tried 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? I think that less than 150 sf or 10 people is quite a reasonable limit.

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Emmanuel Pauwels Owner, Green Living Projects s.l. Feb 07 2013 LEEDuser Member 932 Thumbs Up

and what about toilets? Occasionally there will be more then 25p/1000 ft2 but most of the time there is no-one present. When you consider people that "regularly" occupy the space, there are less then 25p/1000ft2. Is it correct to assume that, in the "regular" condition, it is not densily occupied?

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BR+A LEED Feb 07 2013 LEEDuser Member 28 Thumbs Up

Per USGBC's IEQ Space Matrix, restrooms are not required to be considered densely occupied:

http://www.usgbc.org/ShowFile.aspx?DocumentID=10539

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David Eldridge Project Manager, Grumman/Butkus Associates Feb 13 2013 LEEDuser Member 254 Thumbs Up

Emmanuel -- the restrooms also are likely to have a dedicated exhaust to maintain the required airflow. The potential for multiple people to occupy the space at one time isn't the driver, so CO2Carbon dioxide isn't a key measurement.

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