This prerequisite establishes a baseline for providing a minimum amount of outdoor air to buildings in order to maintain good indoor air quality and keep occupants comfortable and healthy. This prerequisite references ASHRAE 62.1-2007 (with errata but without addenda) and is often more stringent than local building codes, although it is not likely to entail any added costs.
The compliance paths for mechanically ventilated and naturally ventilated spaces, Case 1 and Case 2, are somewhat different and you may need to follow both paths for the same building on a space-by-space basis. Spaces served only by natural ventilation must follow the distinct requirements set out in Case 2, even if other spaces in the same building are mechanically ventilated and are following Case 1. Mixed-mode spaces which alternate between natural or mechanical ventilation must follow the compliance path for mechanical ventilation, Case 1.
For additions and major renovations, confirm that all ventilation systems serving the project meet the ventilation rates required by ASHRAE 62.1 2007, even if the ventilation system design itself is outside the scope of the project. If base building systems do not meet the standard’s requirements, you will need to either increase ventilation rates to comply or provide detailed analysis documenting the constraints and explaining why the base building systems cannot be upgraded.
There’s some confusion in this language on whether mixed-mode refers to a ventilation design with both natural and mechanical ventilation all the time, which needs to be divided up to show compliance, or to a system where either is optional, in which case the worst-case design conditions are for when only the mechanical systems are used and window are shut.
Commercial interior projects will need to confirm that any ventilation systems serving the project meet the ventilation rates required by ASHRAE 62.1-2007, even if the ventilation system design itself is outside the scope of the project. If base building systems cannot be modified to meet the standard’s requirements, you will need to provide detailed analysis documenting the constraints and explaining why the base building systems cannot be upgraded. Systems must be able to provide at least 10 cfm per person to meet this prerequisite.
The 2007 edition of ASHRAE 62.1 combines 62.1-2004 and the eight approved and published addenda to the 2004 edition. The new edition does the following:
If the building relies on the fans for daily ventilation, it is considered a mechanically ventilated building.
Testing in naturally ventilated spaces is not required per 62.1-2007 Sections 4-7 if the outdoor air quality adequately meets 62.1-2007, Table 4-1.
Both operable windows and vents can be used, but only the operable area within those elements can be counted towards the minimum percentage (4%) of net occupiable area.
Local codes may be used to meet the prerequisite if the project team can show equivalency with Sections 7 through 7 of ASHRAE Standard 62.1-2007. Projects outside the US can now also choose to comply with the minimum requirements of Annex B of CEN Standard EN 15251:2007 Ventilation for Nonresidential buildings.
Teams may choose to substitute ASHRAE 62.1-2010, Sections 6.4.1-6.4.2, for ASHRAE 62.1-2007, Section 5.1.1, to document compliance with IEQp1 for naturally ventilated buildings. ASHRAE 62.1-2010 adds geometric requirements that extend the allowed naturally ventilated floor area based on ceiling height and opening configuration.
For CI projects, calculations must be done at the system level for any 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. providing outside air to the tenant spaceTenant space is the area within the LEED project boundary. For more information on what can and must be in the LEED project boundary see the Minimum Program Requirements (MPRs) and LEED 2009 MPR Supplemental Guidance. Note: tenant space is the same as project space..
Determine likely ventilation strategies during preliminary programming: natural, mechanical, or mixed-mode ventilation. This prerequisite is attainable with any of these strategies.
This prerequisite is paired with IEQc2: Increased Ventilation. If ventilation rates are targeted above the 30% ASHRAE requirement, projects can gain both the prerequisite and a point for EQc2. Projects pursuing IEQc2 may follow the compliance path for natural ventilation found in Chapter 2 of The CIBSE Applications Manual 10 (AM10) for both the prerequisite and for the credit.
Many of the strategies that contribute to meeting this prerequisite also support earning other indoor environmental quality credits and should be explored as integrated solutions. See LEEDuser's guidance on the rest of the IEQ section for ideas.
Natural ventilation strategies can reduce costs. Natural ventilation in particular can reduce the need for mechanical equipment as well as operational costs. Displacement ventilation, in which air is delivered at or near floor level at a low velocity, can also reduce ducting and improve equipment efficiency. In choosing a system, analyze life cycle cost tradeoffs.
Check local building codes to determine requirements. The project must either meet ASHRAE 62.1-2007, or local codes if they are more stringent. Since ASHRAE 62.1-2007 is often more stringent than local codes, be sure to review and be familiar with its requirements.
This prerequisite is not likely to require added costs.
Review the Ventilation Rate Procedure methodology in ASHRAE 62.1-2007 Section 6.2 and the associated Table 6-1.
ASHRAE 62.1 recognizes two procedures to prove IAQ compliance: the IAQ Procedure methodology and the Ventilation Rate Procedure. The Ventilation Rate Procedure is easier to apply and is the prescribed path for this LEED prerequisite. Documentation using the IAQ Procedure requires the quantification of contaminant source emissions rates and their reduction, and has historically not been accepted for this prerequisite because it is performance-based and difficult to compare across projects.
If you are pursuing IEQc5: Indoor Chemical and Pollutant Source Control, you must incorporate MERV 13 filters into your filtration system. These relatively tight filters may affect the fan power and fan sizes necessary to provide the required quantities of air. Involve the engineer early if pursuing IEQc5.
Demand-controlled ventilation can greatly reduce energy use while providing large amounts of fresh air to occupants.
Determine whether natural ventilation is feasible based on the project type, use, and climate. Study the natural conditions of the site, such as prevailing wind direction, and orient the building to maximize airflow.
Review the prescriptive requirements for natural ventilation in ASHRAE 62.1-2007 Paragraph 5.1 (with errata but without addenda).
An integrated design meeting will help determine whether natural ventilation is a high priority and should be a primary driver of the design process.
Airflow modeling early in the design process can help teams by evaluating which space planning and envelope design strategies will create effective natural ventilation. An airflow modeling professional may add some upfront costs, while likely improving system efficiency.
Airflow modeling can also help to determine compliance for an engineered natural ventilation system outside the prescriptive measures of ASHRAE 62.1-2007.
Consider the cost implications of natural ventilation. Passive strategies may reduce or eliminate the need for fans and HVAC equipment, but they may also require high quantities of operable windows and a floor plan that is conducive to passive ventilation. Natural ventilation often requires the cooperation of occupants, to open and close windows when appropriate, for example, be sure that your project is likely to succeed in this respect.
Determine the required ventilation rates for indoor spaces based on occupancy and space types. ASHRAE 62.1-2007 tables 6-1 and 6-4 list minimum requirements for particular spaces.
Separately evaluate each space to determine air requirements and what type of ventilation will be best. Metabolic rate of the space activities and the occupant density are factors that determine the amount of fresh air needed in a space. For example, exercise rooms and conference rooms require more fresh air than offices.
An integrated design approach among the mechanical engineer, architects, owners and occupants will facilitate design decisions that impact the HVAC design. For example, space planning decisions will impact the architectural programming of the space as well as access to natural ventilation.
Increasing a project’s ventilation rate brings long-term cost benefits. Good indoor air quality can lower operational costs by increasing occupants’ health and productivity as well as the value and marketability of the building.
For mixed-mode and naturally ventilated spaces, the mechanical engineer should calculate the outdoor airflow rate and communicate the area requirements for operable wall or roof openings to the architect.
The mechanical engineer begins preliminary ventilation rate calculations during project programming in order to set ventilation quality goals for particular spaces and occupancies. The area of a given multi‐zone system should be broken down by ventilation zones, and all zones within that system must meet the minimum breathing zone ventilation air requirements as per ASHRAE 62.1‐2004. For a typical office space, the mechanical design consists of multiple ventilation zones for which compliance would need to be shown on an individual basis.
For mixed-mode ventilation, zone the plan into areas—mechanically ventilated and naturally ventilated—and follow separate compliance calculations for each area.
Determine the applicable floor area for operable wall or roof openings according to ASHRAE 62.1-2007 section 5.1.
Consider using Computational Fluid Dynamics (CFD) modeling to determine proper opening sizes and ensure proper airflow. Some energy modeling programs also have CFD analysis capabilities.
Expect upfront modeling fees for Computational Fluid Dynamics (CFD), but also consider the benefits of CFD modeling: a better-designed natural ventilation system that can bring short-term payback from reduced mechanical systems, and long-term operational savings.
At the first integrated design meeting during schematic design, develop a detailed natural ventilation strategy involving goals for windows, building orientation, space planning, use of atriums, and other access to natural ventilation. Natural ventilation systems may require a more robust and intense integrated design process, of several focused workshops analyzing several alternatives. Computer modeling may be necessary to test various design alternatives to determine which is most effective and efficient.
Hotel and multifamily projects may have difficulty achieving this prerequisite if they are naturally ventilated and have interior spaces that are further than 25 feet from an operable wall or roof opening. These projects might consider increased window areas, shallower floor plates, or using mixed-mode ventilation so that mechanically supplied outdoor air can support areas outside the 25-foot natural ventilation boundary.
The mechanical engineer continues to run ventilation rate calculations during the mechanical design process to inform design development and confirm compliance with this prerequisite. The ventilation rate procedure is explained in section 6 of ASHRAE 62.1-2007. See the attached 62MZ calculator.
Continuing to use an integrated design approach among the mechanical engineer, architects, owners and end users will facilitate design decisions that impact the mechanical design. For example, space planning decisions will impact the architectural programming of the space as well as access to natural ventilation.
Strategically locate air intakes for mechanical or natural ventilation systems to avoid taking in contaminants and odors like vehicle exhaust from parking lots or fumes from garbage storage areas.
Incorporating operable windows into the design for natural and mixed-mode ventilation can help with an additional LEED point for EAc6.1: Controllability of Systems—Thermal Comfort.
Continue running ventilation rate calculations during the mechanical design process to confirm compliance with this credit and to inform the design. The ventilation rate procedure is explained in section 6 of ASHRAE 62.1-2007. See the 62MZ calculator.
Implement energy recovery systems, economizers, low-pressure-drop design, and efficient fans as appropriate to support ventilation rates meeting or exceeding the referenced ASHRAE standard without compromising energy performance.
Avoid oversizing mechanical equipment. Oversized equipment will often increase operating costs and reduce operational efficiency. The correct equipment size will depend on a number of factors, including local climate, total building area, insulation levels, air filtration medium, number of windows and doors, and occupant comfort preferences.
Spaces served by the same VAV (variable air volume) controller can be grouped together in the 62MZ calculator, but grouped spaces should have similar exterior exposure. For example, you can group two perimeter spaces that share a VAV controller, but would want to separate a non-perimeter space even if it shares the same VAV controller.
Laboratory facilities generally require very high ventilation rates. Consider installing separate mechanical systems for lab spaces to maximize return-air mixing. Other strategies may include using a heat exchanger to capture energy from laboratory exhaust, using low-flow or variable-flow fume hoods, minimizing ventilation rates during unoccupied times, or using a dedicated outdoor air system.
Integrating building automation systems can control mechanical systems efficiently and maintain desired ventilation rates while minimizing unscheduled maintenance.
The Ventilation Rate Procedure calculation includes occupancy counts based on space types.
Continue to run calculations and develop flow diagrams to inform the design process and confirm compliance. If you are using a natural ventilation modeler for the project, use the model as a tool to inform design development.
The calculation for operable openings will only apply to the floor area adjacent to the window—25 feet to either side and in front of the opening.
The surface area of window openings must, for compliance with ASHRAE 62.1, be equal to or greater than 4% of the occupied floor area that the design considers naturally ventilated. Multiple windows in aggregate can provide the operable area needed to meet the requirements.
In naturally ventilated multifamily buildings, air infiltration from a pressurized hallway or corridor can contribute to the Ventilation Rate Procedure calculation for areas that do not meet the requirements of ASHRAE 62.1, as long as the corridor is pressurized with outdoor air.
For mechanically ventilated spaces, run ventilation calculations to verify that the final design meets the minimum outside air rates equal to or exceeding the ASHRAE 62.1-2007 minimum.
For naturally ventilated spaces, confirm compliance with the requirements of ASHRAE 62.1-2007 section 5.1.
If natural ventilation strategies are integrated into the design, ensure that key elements of the natural ventilation system, such as operable windows, window actuators, controls, operable atrium elements, and solar chimneys, are not compromised during value engineering. Educate decision-makers about the natural ventilation design and the importance of maintaining all the key components. If these elements are altered in a way that compromises natural ventilation rates, the mechanical system may no longer be sized appropriately.
Fill out the LEED credit form and upload all supporting documents to LEED Online.
Use this checklist for naturally ventilated spaces prior to construction to review plans for prerequisite compliance:
Use this checklist for mechanical systems prior to construction to check prerequisite compliance:
Coordinate the installation of ventilation systems with the project’s commissioning process.
Use commissioning to confirm that installed systems are providing the outside air rates specified in the design.
Monitor outdoor air delivery periodically to confirm that minimum ventilation rates are being maintained. Implement a maintenance program to ensure that mechanical system components are functioning properly.
Test all dedicated building exhaust systems including chemical areas, bathroom, shower, kitchen, and parking exhaust systems to confirm proper fan speed, voltage, control sequences, and set points as applicable. Provide operations and maintenance personnel with manuals and educate them about any atypical maintenance requirements.
Getting feedback on ventilation performance from occupants through surveys can help to identify potential problems that may become expensive if they go unnoticed.
A documented ventilation performance plan can help ensure that systems reach the expected ventilation thresholds.
In projects with operable windows, occupants may not know when conditions are best for opening the windows. Implement a system so that occupants are informed of when to open and close the windows to achieve designed performance and optimal comfort.
Maintain a building operating plan (BOP) that establishes operating schedules and set points and regularly review these parameters against actual building needs. When developing these parameters, consider both time-of-day and time-of-year variations in optimal temperature requirements and be careful to avoid over-conditioning the building spaces with more ventilation, heating or cooling than is necessary.
Adjust reset and setback temperature settings and calibrate controls and sensors. A Building Automation System (BAS) will allow building managers to adjust, monitor and control temperature set points and air volumes throughout the building from a central location. Direct digital controls (DDC) utilized by the BAS will function more efficiently than older pneumatic controls and help to avoid unnecessary use of HVAC equipment during non-business hours and holidays.
Develop and implement a comprehensive Indoor Air Quality Management Plan using the EPA’s “Indoor Air Quality Building Education and Assessment Model” (I-BEAM).
Following the initial audit, the IAQ manager must make periodic inspections to uncover new IAQ issues and monitor the status of previous issues. The I-BEAM tool supplies inspection forms that can be tailored to the project building to facilitate this process.
Establish protocols to manage all significant pollutant sources referenced in I-BEAM that are applicable to the project building.
Ensure that procedures are in place for receiving and responding to IAQ complaints from building occupants. The I-BEAM tool provides sample forms and logs for fielding and recording occupant complaints as well as information about key principles for developing effective communication with building occupants regarding IAQ issues. Strategies for investigating and resolving the issues that trigger occupant complaints are covered by a variety of I-BEAM guidelines.
Excerpted from LEED 2009 for New Construction and Major Renovations
To establish minimum indoor air quality (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.) performance to enhance indoor air quality in buildings, thus contributing to the comfort and well-being of the occupants.
CASE 1. Mechanically Ventilated Spaces
Mechanical ventilation systems must be designed using the ventilation rate procedure as defined by ASHRAE 62.1-2007, or the applicable local code, whichever is more stringent.
Meet the minimum requirements of Sections 4 through 7 of ASHRAE Standard 62.1-2007, Ventilation for Acceptable Indoor Air Quality (with errata but without addenda). Projects outside the U.S. may use a local equivalent to Sections 4 through 7 of ASHRAE Standard 62.1-2007.
Projects outside the U.S. may earn this prerequisite by meeting the minimum requirements of Annex B of Comité Européen de Normalisation (CEN) Standard EN 15251: 2007, Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics; and the requirements of CEN Standard EN 13779: 2007, Ventilation for nonresidential buildings, Performance requirements for ventilation and room conditioning systems, excluding Section 7.3 – Thermal environment, 7.6 – Acoustic Environment, A.16, and A.17.
CASE 2. Naturally Ventilated Spaces
Naturally ventilated buildings must comply with ASHRAE Standard 62.1-2007, Paragraph 5.1 (with errata but without addenda). Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.
Design ventilation systems to meet or exceed the minimum outdoor air ventilation rates as described in the ASHRAE standard. Balance the impacts of ventilation rates on energy use and indoor air quality to optimize for energy efficiency and occupant comfort. Use the ASHRAE Standard 62.1-2007 Users Manual (with errata but without addenda1) for detailed guidance on meeting the referenced requirements.
1 Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.
This updated version of the 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. Up to date, 2nd Edition.
ASHRAE 62.1-2007 should be referenced when designing outdoor airflow monitoring devices.
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. This is the 1st edition.
This Rocky Mountain Institute publication is a case study of the connection between worker productivity and indoor air quality.
This manual provides information on the technology and techniques for the design, operation, servicing, and balancing of environmental systems.
ASHRAE publishes widely used standards and publishes the ASHRAE Journal.
Labs21 is a voluntary partnership program dedicated to improving the environmental performance of U.S. laboratories.
IAQA is a nonprofit organization dedicated to promoting the exchange of indoor environmental information through education and research.
MSCA is a national trade association that provides educational resources and training programs on sustainable service and maintenance practices for HVACR contractors.
Located in London, this organization publishes a series of guides on ventilation, including natural ventilation.
This website contains reports from an extensive EPA modeling study that assessed the compatibilities and trade-offs between energy, indoor air quality, and thermal comfort objectives for HVAC systems and formulated strategies to achieve superior performance.
This is a Microsoft Excel calculator that accompanies the ASHRAE 62.1 reference standard. The calculator allows users to plug in variables for specific project types and run the Ventilation Rate Procedure.
Public domain software from NIST (National Institute of Standards and Technology) that has natural ventilation sizing tools, and flow models to analytically predict room-by-room airflows.
Public domain software from NIST (National Institute of Standards and
Technology) that has natural ventilation sizing tools, and flow models
to analytically predict room-by-room airflows.
ASHRAE released an app for iPhone, iPod touch, and iPad that allows you to perform comprehensive minimum ventilation calculations for a wide variety of commercial buildings based upon Standard 62.1, using either I-P or SI units. This app is based upon the 62MZCalc.xls. Now, you can make calculations at a meeting and know if your project meets IEQp1 or IEQc2.
This example ventilation rate table from 23 High Line provides guidance when developing prerequisite compliance documents for your project.
This example air riser diagram from 23 High Line shows the mechanical ventilation supply for the building. It is the ducted diagram showing how air will be supplied to building occupants. Use this as an example for how to document ventilation effectiveness compliance.
Use this example mechanical schedule created from 23 High Line for guidance when developing ventilation effectiveness compliance documents for your project.
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."
Documentation for this credit can be part of a Design Phase submittal.
Hello in a Museum, we have an uderground open space, that, on our understanding is an exterior space, as it is outside the Access vestibule. It has a roof overhang but have a completely and permanently open side, with more than 40ft and the total height of the space, in which there are the acces stairs and a water feature. However there will be two people in this space working in an info booth. In our undesrtangind, this is an exterior space with the shadow of the overhang, and therefore have no thermal conditioning or mechanical ventilation. Is this space is required to be included in the Ventilacion calculations of the ASHRAE Standard 62.1 (Natural or mechanical) and in the Thermal comfort requirements (ASHRAE Std. 55). We thing it's excluded as an outdoor space, but want to confirm.
Hi, I just received the feedback from reviewer. We have 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. to supply 100% OA to the space and FCUs for secondary recirculation. Reviewer said:
"The design system primary supply air flow volume (Vps) don't match the supply air flow of AHU in equipment schedule. + Calculation must be performed at the worst-case condition when 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 is at minimum flow."
I'm try to figure out where is the error in my calc. I'm checking Vdzd, Ds, Vpz, Vps. For example, Vdzd = 1,400 (OA /SA by AHU) + 10,000 (recirculated by FCU) = 11,400 cfm. How can I adjust (Ds). I had set Ds = 100% beforehand. I think that had made supply airflow by AHU was much larger than that in equipment schedule. And I just check that Vdzd * Ds = Vpz (supply airflow by AHU) = 1,400 cfm. So is it correct that I adjust Ds = 1,400/11,400 = 12%
I think the error is in "Vdzd". You should enter here the total air supplied by all the FCU located in the space. This number must match that showed in the mechanical schedule. You shouldn't add OA, since it is already mixed in the FCU.
"Ds" is ok in 100%. You can lower this percentage in case you now that all spaces cannot be fully occupied at the same time, for instance: workers can be either at the cafeteria or at their workstation, but they cannot be at both places at the same time (as long as string theory is not proven right).
I would like to know if there's any way I can consider walk-in closets in a residential building as unoccupied spaces. The IEQ Space Matrix lists them as occupied, but this seems silly, since nobody spends any significant time there. According to 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. (1 hr per person per day), walk-in closets are definitely unoccupied.
Furthermore, 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 #1888 states, "Note that walk-in closets are excluded from the Standard, since they cannot be considered as "occupiable space" by the Standard's definition (page 4 of ASHRAE Standard 62.1-2004)." So it seems like the CIR and ASHRAE 62 both disagree with the IEQ space matrix. Also, NYC Mechanical Code, where this project is located, classifies walk-in closets as unoccupied.
So if I take this all together, it seems like there may just be a typo in the IEQ Space Matrix, since the CIR, ASHRAE (and NYC Code) all disagree. Has anyone had any experience with walk-in closets? Can I get away with not ventilating them? Thanks in advance.
Wow, I am glad you brought this up because I wouldn't have even thought of a walk in closet as being occupiable.
You point out a serious discrepancy between ID #1888 and the IEQ Space type matrix. I'd email firstname.lastname@example.org about this otherwise you might have trouble during your LEED review.
I think they are just changing their tune on this since the 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.. Even though it is not regularly occupied the "equipment retrieval" (getting clothes) is not "occasional" since presumably people get dressed every day.
Therefore according to note #14 they would want you to ventilate it.
I think "regularly occupied" only applies to IEQc8, IEQp1 relates to "occupied" vs "non-occupied" spaces.
Thanks Kathryn...I emailed that address; I'll let you know what happens!
I noticed, I cannot enter rooms that require exhaust like restrooms and lockers. Do I exclude them on the excel spread sheet?
which is the correct abbreviation for a single duct constant volume system with fresh air introduced at the fan?
I am calculating the ventilation requirements for a conference room. From the ASHRAE Table 6-1 I selected .06 cfm/ft2 and 5 cfm/person. The room has occupancy of 8 people. Since the room is not regularly occupied, do I uses 0 people for the actual occupancy when I do the Leeds compliance?
Would this be the same for a file storage room, copy room and library?
You should use the peak occupancy, which is 8 people.
There are some allowances for time averaging in spaces with variable occupancy, but you wouldn't apply that here. Just use the peak occupancy. The LEED reviewers want to know that the system can provide sufficient ventilation for worst-case conditions at peak occupancy.
I am having troubles understanding what is a single zone system and a multiple-zone system and how to fill out the forms. Example: I have a zone with eight individual offices and corridor on a air handler and another zone with restrooms, library, records and corridor fed from a different air handlers.
1.A single zone is when a fan is providing outdoor air for a unique zone, for instance a dinning room. In this case you should complete the ventilation calculator in the LEED form.
2.A multiple zone is when a fan is providing outdoor air for different spaces at the same time (restrooms+library+records+corridor...). In this case you should use the excel calculator (.xls file) downloadable from this web and upload it to LEED online.
we are trying to file compliance for both IEQ P1 & C 1,it would be great if someone could help me clarify on the below:
1)if a meeting room is served by a dedicated FCU;
Does the meeting room require both the airflow measurement device as well the CO2Carbon dioxide sensors or just the CO2 sensor will do?
2) We have CO2 sensors in the return air duct that modulate the airflow based on occupancy. When there is less/no occupancy if modulates the damper to close In order to save energy.
Now when we program the airflow device serving the same space to maintain a minimum airflow, it does not complement each other. As airflow devices are programmed to maintain a minimum airflow even with no occupancy. How to resolve this?
I can hep you with (1): If your meeting room is mechanically ventilated, then you need to install an airflow measurement device in the duct providing outdoor air. If your meeting room is naturally ventilated, then the CO2Carbon dioxide sensors will do.
For (2) I would say that you can use your demand controlled ventilation instead of the airflow measurement device required by the credit. Since this is out of the credit requirements, I would submit an inquiry through the USGBC web-site for your particular case.
Thanks for the comments. We have a project where some area are served by 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.'s and some areas served by constant flow FCU's with individual outdoor air supply fans. Now we are providing airflow measurement device for all AHU's. Since the number of FCU's are quite many & are constant volume, can we just provide CO2Carbon dioxide sensors within the rooms for all spaces served by FCU? instead of airflow measurement device (including non-densely occupied zones)so that we are in compliance with both IEQp1 & IEQc1.
Hi Stella, I guess your concern is about the cost associated with installing many measuring devices. We usually drop this credit when there are many outdoor air fans. However, if you read carefully the credit you only need to install this device "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 concern is not the cost rather the use of the Airflow stations; the FCU’s are constant flow and doesn’t have any damper to modulate the airflow, even if there is an alarm by the AFS. Hence I don’t see the point of installing one. To answer your question, the FCU’s servers non densely occupied zones as well. So I would rather put in a CO2Carbon dioxide sensor within the room to generate the alarm. Please advice.
We are working on a project with 418,000 sf with mechanical ventilation of OA in most of the spaces and a non-24 hours chiller.
There is a small space with 110 sf and one person, with 24-hour occupancy and a independent HVAC system.
We are pursuing credit IEQc2 and IEQc5, then it's not practical to use a fan with 30 ft long duct and MERVMinimum efficiency reporting value. 13 for 20 cfm OA flow rate.
For this reason we want to use natural ventilation for this space.
The space doesn't have a direct opening to the outdoors but there is a shaft with an opening to the outdoors on the top that runs alongside the space.
Can we design an opening connecting the space with the shaft with an opening of 4% of the net occupiable floor area and comply with the section 5.1.1 from ASHRAE 62.1-2007?
We would be assuming the shaft as outdoors with this approach, since it has a free opening to the outdoors on top.
If the opening in question is permanantly open (or easily able to be opened by occupants while the room is occupied), at least 4% of the floor area and within 8 meters of the floor area being served by the opening... it will comply.
The standard allows either the wall or roof to be used as the opening.
Hope this helps.
Thank you, David.
I appreciate your response.
I have a Pantry zone in an office building that is conditioned spearetely by a FCU. This zone has refrigerator, coffee maker, and recycling bins. The zone is supposed to be used an occupant or by an office boy only to prepare drinks. Knowing that I didn't include this zone on the forms during preliminary design submittal and didn't get feedback regarding it; should I include this zone on the LEEDOnline form during final design submittal or not? if so, and I'am ventilating this zone by a window, should I mark that "The project building is naturally ventilated, in part or in whole" only because of this zone?. I'am using V.03 forms.
Do centrifugal closed-circuit cooling towers have to comply with table 5-1, of ASHRAE 62.1-2007?
In our project, the closest distance from the cooling tower to the DOAS is 6 meters (horizontally) and the discharge is on the top of the tower (3 meters tall).
Are we complying with 62.1-2007?
Thanks in advance.
You need to be 25 ft from the exhaust and 15 feet from the intake. These are areas of moisture laden air with chemical contaminants. The distance is actual distance in space, not horizontal projection.
A hotel project that the kitchens have independent ventilation and outdoor air system , whether the ventilation of kitchens should be included in the calculation?
Yes, you should include these in the credit documentation.
We have a project with 3 lobbies located in basement parking. The lobbies are not 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., but are circulation spaces connecting to the main reception and lobby on the Ground floor via lifts and a staircase. The main reception and lobby are being supplied with outdoor air. Do we need to supply outdoor air to the basement lobbies?
Your description does not really illustrate how the basement lobby is connected to the ground floor or to the parking garage itself. Based on the description above though, you should comply with ASHRAE 62.1-207 requirements for lobby ventilation.
Hi Andrew, thank you for your reply. The lobbies in question are linked with a communication staircase that leads all the way up to the roof so there will be adequate ventilation of these lobbies through the upper ventilated levels,also these basement lobbies have self-closing doors installed on each basement level .The basements are being CO2Carbon dioxide monitored to ensure that there is no build-up of toxic gasses and is ventilated accordingly. The basements where the small lift lobbies are located are purely for parking and as I understand ASHREA only addresses 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.. So in essence we are debating the definition of Lobbies?
Can u suggest the Ventilation rates for the Production / manufacturing areas for a Pharmaceutical clients because ASHRAE doesn't mention any for the Production in the Table 6-1
Sriram, ASHRAE would not define ventilation rates for your application. You need to refer to the U.S. Pharmacopoeial Convention applicable standards.
Thanks for the reply,
We are using the in house standards of the Pharmaceutical client Which are More stringent than ASHRAE, But From LEED point of view and to compare with ASHRAE base case can we assume the Ventilation Rates of Wood / Metal Shop given in Table 6.1 of ASHRAE- 62.1?
Andrew, can you please share the link for the US Pharmacopoeial Convention Standards?
Also can anyone give the reference from the LEED Reference guide / Addenda, that justifies the use of above standard as a baseline for IEQc2 credit?
In one of our project we have a Main corridor that is completely open with just a parapet wall and roof overhang. Now we have another small corridor that is connected to this Main corridor. The ventilation for this small corridor is through the Main corridor. The farthest point on this small corridor is more than 25ft from the main corridor wall/opening. Can it still be considered as naturally ventilated?
not per ASHRAE 62.1 definition, you may need to include a fan at the farthest point.
If it is not an enclosed space then it does not need to be included. Also, corridors can be considered non-occupiable spaces according to the 62.1 users' guide, therefore they would not need ventilation.
This gets to be a little tricky, the use of the corridor will dictate if ventilation is required.
"corridors that are used primarily for emergency egress do not have to be ventilated. Corridors that are more frequently occupied, such as those used for the delivery of merchandise in a retail mall, must be ventilated." per ASHRAE User Manual Example 6-E.
Also, review the IEQ Space Matrix located at: http://www.usgbc.org/resources/eq-space-type-matrix
This spreadsheet provides guidance when applying this IEQ prereqs/credits to various occupancies.
Thank you for the response. The main corridor of this building is along the external facade and hence it is semi open with just a roof and a parapet wall (completely naturally ventilated). There is a small internal corridor that branches from this main corridor. Now this internal corridor has walls on the three sides and the fourth side is open connecting to the main corridor. This internal corridor has roof and is used for access to open office spaces and meeting rooms.
Will it be acceptable to claim this space as non-regularly occupied space?
If not what kind of fans do we need to provide as it is not a completely enclosed space? Can we just use a normal ceiling fan/wall fan to comply? Or do we need to provide MV?
Appreciate your inputs.
Corridors are considered nonregularly 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. however that does not exclude them from the ventilation requirements.
I'd use the 62MZ to calculate the ventilation required for this corridor and size the fan accordingly. The fan can exhaust out the wall or roof.
I am not sure what you mean by "MV".
Thanks David. I am not sure if we can include exhaust fans as all the three walls are internal walls and cannot have any opening. There are floors above the corridor and hence cannot have any opening on roof either. Can just using a domestic ceiling fan/wall fan suffice, as it’s not a completely enclosed space?
Thank you for the additional info.
A ceiling fan, also known as a destratification fan, would not suffice since it mixes air rather than transfers air. A wall fan should suffice since it transfers air.
How long is your corridor and what are the dimensions of the opening to the outdoors? Natural ventilation requirements are meant for "openable" areas, not permanently open areas. If your corridor communicates directly outside without any obstruction, then you likely do not need mechanical ventilation to satisfy ASHRAE 62.1.
Thanks Andrew & david.The corridor is “L” shaped with a total length of 18m and 1.8m wide. There are no operable windows and it is permanently open. The upper part of the corridor opens to the exterior (no wall-permanent opening 4m X 1.8m) and the lower part of the corridor leads to various room. So it has opening at one end and rooms at the lower end. Can it be considered as a unenclosed space and could it be exempted from Natural ventilation calculations?
Hi, would Appreciate your comments
ASHRAE 90.1 defines "enclosed space" as a volume substantially surrounded by solid surfaces such as walls, floors, roofs, and openable devices such as doors and operable windows.
From your description I believe the corridor to be substantially surrounded and thus would define it as an enclosed space.
Our project has some of the areas that are mechanically ventilated (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./FCU) and some spaces that are naturally ventilated. We have provided the details for both. Though the “Table IEQp1-A5. Natural Ventilation” shows “Y” for Compliance with IEQ Prerequisite 1; the “Table L-17. Natural Ventilation AHU Summary” shows “N” for Compliance with IEQ Prerequisite 1. Please advice!
Does anyone have a clue?
click "calculate" after any or all data is entered. both "calculate" buttons should be clicked for Table IEQp1-A5 and Table IEQp1-A6 for Table L-17 to display correctly.
If the tables are not linking correctly note this within a narrative when submitting.
If what David says does not work, then you will need to provide more information. Your post is quite vague as far as pointing out what might be a potential problem.
Although I read almost all the comments related with the ventilation requirements of the storage rooms, I could not find the exact answer for my question.
In our project we have a storage room (definitely will be visited maybe once a month for 10 min and will store no chemicals etc..), with just a small operable window, which is not providing %4 area condition.
Some comments say that "Storage Rooms" can be excluded from VRP calculations, but also some refers to ASHRAE 62.1-2007 table for Ra rate to be provided. So my question:
Should I exclude this area with a strong narrative for this prerequisite? or
The natural ventilation with small window for a storage room will be enough although it is not %4 by area?
My understanding is that a storage room that is visited only once a month for 10 minutes can be classified as "Inactive" Storage. Spaces such as these do not need to be included (per the 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. matrix spreadsheet), because they are considered unoccupied spaces.
Whether there is a window or not is irrelevant for compliance because the space does not have to be included at all.
Thanks Julia for your comment. Seems like no LEED User experts are replying any questions here any more...
I concur with Julia's comment.
Inactive storage is further defined as "unoccupied space" thus not requiring ventilation per IEQp1. Be sure to describe the function/use of the room to reviewer when submitting your project.
A data center is applying for LEED-NC v2009. There are 5 PAUs (Primary Air Unit). 4 of them will serve the equipment rooms. One will serve the equipement rooms and office areas. Now, I am doing the calculation of mechanical ventilation. Should I only calculate the office areas (staffs work in these rooms), or should I do the calculation cover all the 5 PAUs?
if the equipment rooms can be defined as "inactive storage" than only the office areas need ventilation calcs.
How do you show compliance with case 1 for GBCI, mixed-mode ventilation? Copied from the Reference Guide: "Project teams can use any acceptable engineering calculation methodology to demonstrate compliance." That does not sound very clear and like GBCI can reject any calculation.
Any experiences with this part?
Thanks alot in advance,
What is the difference between breathing zoneThe breathing zone is the region within an occupied space between 3 and 6 feet above the floor and more than 2 feet from walls or fixed air-conditioning equipment. (AHSRAE 62.12007) outdoor airflow and room outdoor airflow rate? How do I find the room outdoor airflow rate for bedroom/living room type spaces
We work on a private office building where toilet facilities are composed of several individual toilet rooms.
Reading the ASHRAE 62.1, we are not sure about the occupancy category of these spaces : is it private or public toilets ?
It sounds like these would be considered private. Note E says that the rate is for a toilet room intended to be occupied by one person at a time.
So we can considere that "public toilets" are only urinals area, and toilet room partition with partial height-cubicle panels ?
In IEQp1 i already Upload 62MZcalc and Results from a Simulation Software and Fill the narrative Tab and all other but my check compliance is still indicate (Y)
so my Doubt Whether we need to fill Appendix or not
and Our Project Location is Outside US
Is it a compulsory to design mechanical ventilation by using local code even if ASHRAE Standard is more stringent in order to score IEQ Credit 2: Increased Ventilation?
I got a problem to score IEQ c2 because of this. Although in IEQ p1 it showed that i have complied with IEQ c2 for all mechanical ventilation AHUs (by complete and uploaded AHSRAE Calculator 62MZ), but when i want to complete IEQ C2 form, it showed the opposite result.
The forms are in the same version?
We had a similar problem and realized the IEQp1 was a version 4, while IEc2 was version 5.
Yes. Both forms are in the same version.
I never face this problem before. So what have you done to overcome the problem?
I haven't submitted for IEQc2 recently, but you should be able to base IEQc2 calculations on ASHRAE 62. I don't believe you will be required to show 30% greater than local code as long as you can show 30% greater than ASHRAE 62.
If there is something in the template that seems to be calculating improperly, you can try submitting an explanation under the Special Circumstances section.
We asked for an update of IEQp1 form to version 5.
Last time i didn't showed the calculation for 30% of local code requirement. I just showed the calculation from 62MZ and had complied everything. Now, it didn't appeared the same result as my last project even in the same form version. However, will try to submit an explanation under Special Circumstances section.
Thanks Julia and CT G
Can please someone give his/her suggestion on the question I have below ?
I received a comment for (Design Preliminary Submission) ventilation calculations indicate a total area (3,055 sqf) significantly less than plf2 (6219 sqf) for the IEQp1
Our response is;
The areas have been revised to match those of table EAp2-1 and to more closely match the architectural floor plans. 3055 sqf was brought up to 4429 sqf and the areas where are not included are the elevator, stairs, jan closet, small restroom, elect & mech spaces and storages (sum of non-ventilated areas is 1489 sf).
My questions is;
Plf2 shows 6219 sqf
Energy model is based on 5812 sqf
IEQp1 - ventilated area is 4429 sqf ( is this sqf reasonable for resubmission ? Does it need to be same as the energy model ? )
Principal, Director of Sustainability
Westlake Reed Leskosky
Mechanical and natural ventilation designs must comply with requirements to mitigate environmental tobacco smoke.
The amount of fresh air the HVAC system is designed to process has a direct correlation to the buildup of carbon dioxide.
Increasing the ventilation rates 30% above the ASHRAE standard will help teams gain IEQp1.
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