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. Naturally ventilated spaces 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 (with both mechanical and natural ventilation) must follow the compliance path for mechanical ventilation, Case 1.
New construction additions 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 do not meet the standard’s requirements, you will need to either modify the base building system or provide detailed analysis documenting the constraints and explaining why the base building systems cannot be upgraded.
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.
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.
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 create a more effective natural ventilation design. If the data is used early in the design to help inform team on such thing as space planning and building envelope design. An airflow modeling professional may add some upfront costs, while likely improving system efficiency and effectiveness.
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.
I am working on a data center and not sure about ASHRAE 62.1-2007 outside air requirement. Table 6.1 list 2 types: Computer lab at 10 CFM/ person and 0.12 CFM/Sqf and Computer no printing at 0.06 CFM/Sqf only.
it is not really clear where the data center will fall.
Any help will be appreciated.
When you say data center it is unclear what type of room you are referring to. The first thing that comes to my mind is a server room. For the most part, these are unoccupied spaces and do not require ventilation; much like an electrical room. You need to pay special attention to whether or not you have a UPS system in the same space and also if you determine that there are any local contaminants that will need to be exhausted from the room.
I am working on a Tier III data center with the same question. Our server room will be occupied for a few years with between 1 to 5 FTEFull-time equivalent (FTE) represents a regular building occupant who spends 8 hours a day (40 hours a week) in the project building. Part-time or overtime occupants have FTE values based on their hours per day divided by 8 (or hours per week divided by 40). Transient Occupants can be reported as either daily totals or as part of the FTE. Residential occupancy should be estimated based on the number and size of units. Core and Shell projects should refer to the default occupancy table in the Reference Guide appendix. All occupant assumptions must be consistent across all credits in all categories.'s working on daily basis. FTE's will taper off over time as server space is leased. I am therefore wondering what is correct CFM? Our UPS is outside the space.
yes its a server room, UPS is located in a separate room with its own system.
the room will be unoccupied just for maintenance. we have decided to bring outside air for pressurization. that will be close to the 0.06 CFM / Sqf.
Kimberly, in your case I would use the same rates as a computer room without printing.
Houcine, you will be fine with a small amount of pressurization air. You are simply doing more than what is required.
We are working on a multifamily building with naturally ventilated interior kitchens located next to the living/dining rooms that have operable windows. The kitchens meet 62.1-2007 section 5.1.1, having unobstructed openings to the living/dining rooms exceeding 8% of kitchen area and 25 SF. However, IEQp1 form v5.0 doesn't have a table where these rooms can be entered. There is a table for naturally ventilated rooms within 25 feet of operable windows, but not for the interior rooms that are ventilated through adjoining rooms. How can these areas be represented in the LEED form? Thanks.
Are the kitchens themselves also within the 25'?
Joseph, the kitchens themselves aren't within 25 feet of the windows. From the wording in Section 5.1.1, it doesn't seem it's required that the interior rooms need to be within 25 feet, but do you think that is a requirement?
Erika, I have always considered the language to mean that all spaces must be within the 25'. I have seen LEED review comments that agree with this interpretation.
Erika, I am in agreement with Andrew. The way I see it is that it wouldn't totally make sense if an "adjoining room" outside 25' could comply, but spaces beyond 25' within the same room wouldn't comply because they were beyond 25'. I too have seen reviews where this was interpreted like this.
Joseph, Andrew, thank you for your responses. I do have some interior rooms that are within 25' from the window, how would those be entered in the LEED form? I am thinking of entering both the interior room and it's adjoining room with the window as one large room in Table IEQp1-A5 and provide a narrative explaining that they are two separate rooms. Do you think I can submit something better?
I think that would be fine as long as you have the narrative. Remember that you are sure to get a comment along the lines of "The 25' dimension may not be impeded by walls." I always upload a plan showing a dimensioned line from the openable area to the furthest occupied corner.
We have a multifamily building where the naturally ventilated kitchens are interior rooms, located next to the living/dining rooms that have operable windows. The kitchens meet the requirement of 62.1-2007 Section 5.1.1, having unobstructed openings to the living/dining rooms with free area exceeding 8% of kitchen area and 25 SF+. However, we are not sure how to input this information in the LEED IEQp1 form v5.0. Under natural ventilation in that form, there is a table to input the rooms that have operable windows within 25 ft, but no table for the interior rooms that are ventilated through adjoining rooms, like the kitchens in our project. How should these kitchens be entered in the LEED form? Thanks.
I'm working on the certification of a completed project in Russia. Russian standards for OA requirements are 60 CFM/person, so I know that there is 'enough' total OA for the occupants (both for IEQp1 and c2). Our challenge arises in a couple of corridors that are designated 'critical zones' in the 62MZ calculators. In most cases, these corridors are only used by service people to access electrical closets and other service/'back of the house' areas.
The building is already built, so putting in additional ductwork, etc. ain't gonna happen. (BTW, the design and as-builts showed the necessary equipment in place, but during Cx1. Commissioning (Cx) is the process of verifying and documenting that a building and all of its systems and assemblies are planned, designed, installed, tested, operated, and maintained to meet the owner's project requirements.
2. The process of checking the performance of a building against the owner's goals during design, construction, and occupancy. At a minimum, mechanical and electrical equipment are tested, although much more extensive testing may also be included.--now on pause--we found the discrepancy)
First question, Do these seldom-used areas need to comply with the p1/c2 requirements?
Second question, What are folks' thoughts about suggested fixes?
One idea is to install some louvers in doors of adjacent rooms that have net negative air flow so that the corridors will receive the necessary air flow. If we use this strategy, would the use of louvers affect the air flow & how would we account for this?
Another idea is to install a small exhaust fan at the end of the corridors to pull additional air in. In all cases, the corridors are partially adjacent to spaces with significant 'extra' supply air.
Thanks in advance for any ideas.
Non-occupiable spaces do not require ventilation. The best description for this is provided by the ASHRAE 62.1 User's Manual. From the 2007 Manual:
Only "occupiable spaces" are required by the Standard to be ventilated. By definition, this excludes "those spaces intended primarily for other purposes, such as storage rooms and equipment rooms, that are only occupied occasionally and for short periods of time." So if an equipment room, for example, is expected to be occupied only occasionally (e.g. for servicing equipment), ventilation is not required...stairs and corridors that are used primarily for emergency egress do not have to be ventilated...
Thanks, Hernando, I think we should be able to demonstrate that these spaces should qualify as 'non-occupiable' by the ASHRAE definition.
Rob, your claim the corridors are not regularly occupied would be strengthened if you can provide a plan view showing that no access is provided to any 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.. I included the statement about emergency egress stairs and corridors from the ASHRAE 62.1 User's Manual (2007 version) because that could prove to be useful to you and other people who use LEEDuser.com.
The quote from the User's Manual I provided comes from: "Example 6-E—Occasionally Occupied Spaces" on page 6-14.
in this project, each regularly occupied space have ventilation grill and OA grill - separately.
in the LEED form, should i determine the Vdzd are both the ventilation CFM and OA CFM?
Your question is quite confusing. What is the make-up of the air coming out of each grille?
sorry to confuse you. for example, in a meeting room, we have dedicated FCU unit and dedicated OA grille .
Even when FCU were off, the OA still fill up the room.
Is the value for Vdzd are the combination of FCU and OA CFM?
No, you should use the OA flow as the Vdzd. It seems from your description that if you require anything less than 100% OA using that method then you are fine. Make sure that your Ez is 1.0 if you are not supplying hot air through the dedicated vent.
I'm confused with two items on table 6-4: "Locker/dressing rooms" and "Locker rooms". The later requires twice the exhaust rate of the first item. Would it be accurate to say that locker rooms at sport facilities would require more exhaust while locker rooms at offices would require less exhaust?
Thanks in advance.
It isn't exactly clear in the minimum exhaust rate table what the difference between a locker room and a locker/dressing room is, is it?
I would interpret it as a Locker Room (with the greater exhaust rate required) as being a locker room with showers. Whereas a locker/dressing room would be a place for changing clothes but not for showering. This would explain the difference in the two exhaust rates, and I notice there is no separate line in the table for shower rooms.
Thank you very much!
Did anyone had ever to explain to the reviewers discrepancy between the area documented in IEQp1 and the total area in PIf3?
We had 33% of the total area that were NOT documented in IEQp1. Which is quite a lot and we are now listing all the unoccupied spaces in our response:
- this project is a manufacturing plant with large inactive and unoccupied areas that represent 20% of the total area.
- There are "unfinished spaces" that are unoccupied and represent 3% of the total area
We are dealing with a remaining of 10% that represent elevators, stairs for egress, small mechanical shaft and rooms etc...
We are unsure if a 10% discrepancy is ok? has anyone had experience with this type of comment?
Yes, I have listed all of the space in the building that were not included in the calculation and then demonstrated that the left over discrepancy area is walls and such since PIf3 is gsf and EQp1 is nsf. Explain it clearly and you will be fine.
Thanks Andrew, do you remember the difference in % you had between gsf and nsf?
I think it was around 5%.
Dear LEED Team,
just calculated the ventilation rate according the ashrae 62.1.2007 for a office building and now really wonder about the low outdoor air rate:
Density: 100 ft²/person (net occupiable area in zone)
OA per person: 5 cfm
OA per m²: 0,6 cfm/ft²
Combined OA per person: 5 cfm + 0,06 cfm/ft² x 100 ft² = 11 cfm/person
Compared to the European standard with around 20 cfm this seems to be very less. In cubicle offices with lower density it even gets worse. At the same time the ASHRAE recommends a CO2Carbon dioxide level of 1000ppm - which is not reachable with the given 11 cfm/person.
So, how can this be explained?
Although still widely cited, the 1,000 ppmParts per million. CO2Carbon dioxide concentration is an old ASHRAE reference from 62.1-1989.
I don't believe 62.1-2007 refers to that CO2 level. ASHRAE has converted to a dual component method of recommended minimum ventilation rates, based on air flow per unit area plus air flow per person. Apparently, the new ventilation rates recommended are considered adequate even though they can result in CO2 concentrations well above 1000 ppm.
Marco, you calculated Vbz, but you need to calculate Vot to determine how much OA is needed for compliance.
We are looking to certify a naturally ventilated project NC-v2009 (bus terminal) that is located in a Hot and Humid zone. The building complies with ASHRAE 62.1-2007 minimum conditions for operable windows and beyond.
Nevertheless, we understand that optimal indoor thermal comfort conditions would be difficult to accomplish, but the client is determined not to invest in any mechanical equipment.
Is there any part of ASHRAE standards or LEED requirements to support our position to help ventilation with mechanical equipment in order to ensure the thermal comfort inside the building?
Note. The client only wants to fulfill the minimum requirements for the prerequisite "IEQp1. Minimum 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", not credits related with thermal comfort (IEQc7.1).
There is nothing requiring them to have mechanical ventilation or conditioning. I do not think that your question relates to USGBC or LEED. You may want to write a letter of recommendation for the system that you think should be installed so that you can refer back to it in the future if comfort issues arise.
I'm working on a project for a deposit. On site there is a large exhaust fan on the roof.
This deposit have a small bathroom with mechanical exhaust however, is not possible to have this air outside due to the type of envelopment site.
Can I exhaust this air into the deposit so that the exhaust fan of roof send outside? That would be a mixed ventilation?
It sounds like your "deposit space" is going to be either class1 or 2 air. In that case, you cannot exhaust Class 2 (bathroom) air into it. See ASHRAE 62.1-2007 paragraph 188.8.131.52.
But I if I consider that my storage is class 4, as shown in Table 6-4?
In this case I can transfer air to the storage, and the exhaust fan of storage releases this air to the outside.
Is it a chemical storage space?
We don't have this information. The client does not know yet.
The storage is very large.
The bathroom is very small in relation to storage. Maybe with a narrative explaining you think would work?
In my opinion, you should duct the bathroom exhaust to the outdoors. It is up to you how you want to document your design but I would personally never err on the side of a code deficiency just to allow a LEED prerequisite to be achieved a little bit easier. Unless you know that it will be Class 4 storage then this is the only advice I can give you.
Ok, thanks for this advice Andrew.
Dear LEED Users,
I have a question regarding the prerequisite 1 of IEQ Section: Minimum Indoor Air Quality Pollution.
According to the Ventilation Rate Procedure of ASHRAE Standard 62.1-2007, the design outdoor air flow in the breathing zoneThe breathing zone is the region within an occupied space between 3 and 6 feet above the floor and more than 2 feet from walls or fixed air-conditioning equipment. (AHSRAE 62.12007) should be determined in order to remove contaminant from both people related sources and area-related-sources (coming from materials).
Our project validates the following credits (under LEED 2009 NC):
- IEQ Credit 3.1 – Construction IAQ Management PlanA construction IAQ management plan outlines measures to minimize contamination in a specific project building during construction and describes procedures to flush the building of contaminants prior to occupancy. – During construction
- IEQ Credit 3.2 – Construction IAQ Management Plan – Before occupancy
- And IEQ Credits 4.1 to 4.4 – Low-emitting materials
Considering that these credits are met, especially the fact that only low-emitting materials will be installed and that a flush-out will be conducted before occupancy, is it coherent to say that they are no area-related-sources?
If so, is it OK to only take into account the outdoor airflow required per person ?
Thank s for your help.
No it is not. You need to include the ventilation requirements for Rp and Ra.
OK, but 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. Procedure allows credit to be taken for design technique such as Low-emitting materials, right? Would it be a better option for us to use this path for this credit?
Another question is for large spaces with low occupancy density. For example we have a hotel guestroom of 96m² (~1033 ft²) that will host only 2 persons whereas default occupancy value is 10 persons per 100 m (so basically 5 time higher than ours).
in addition, considering a ceiling height of 2,5m (8.2ft) it represents a volume of 240m3 (~8475 ft3). Therefore human pollution is diluted so much that we should be able to neglect it. Isn't it ?
LEED has traditionally not allowed 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. procedure for this prerequisite. Although there are ASHRAE papers showing that the IAQ procedure results in lower energy use and better indoor air quality, this information has fallen on deaf ears at USGBC.
LEED 2009 Text:
“Meet the minimum requirements of Sections 4 through 7 of ASHRAE Standard 62.1-2007, ...
CASE 1. Mechanically Ventilated Spaces
Mechanical ventilation systems must be designed using the ventilation rate procedure or the applicable local code, whichever is more stringent.”
Note that this requirement specifically calls out the ventilation rate procedure.
The following 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 only technically applies to LEED 2.2. I'd love to see someone post a CIR asking if it is still applicable to LEED 2009 and LEED V4, but I expect that the answer is yes, it does apply and no, they won't allow the IAQ procedure.
"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.
MPR/Prerequisite/Credit: IEQp1: Minimum Indoor Air Quality Performance
Posting Date: 5/15/2007
ID Number: 5053
Primary Rating System: New Construction v2.2
The CIR is inquiring if the IAQ Procedure, as described in Section 6.3 ASHRAE Standard 62.1-2004, can be used in place of the Ventilation Rate Procedure of the same Standard to document compliance with the requirements of this prerequisite. The Ventilation Rate Procedure methodology found in Section 6.2 of ASHRAE 62.1-2004 is the required approach in EQp1, since it is prescriptive and therefore more straightforward to apply. The Ventilation Rate Procedure is based on contaminant sources and source strengths that are typical for common space types listed in the Standard. The Indoor Air Quality (IAQ) Procedure methodology found in Section 6.3 of ASHRAE 62.1-2004 and proposed by this project team is performance-based and relies on identification of contaminants of concern, sources for those contaminants, concentration targets, and perceived acceptability targets. The project-specific nature of the IAQ procedure methodology makes it less commonly used and more difficult for USGBC to evaluate. Therefore USGBC cannot allow its use to show compliance with LEED NC v2.2 EQp1. Please note that the intent behind this prerequisite is to encourage designers to take the most stringent and conservative prescriptive approach to providing fresh air. The language of the prerequisite asks designers to compare the rates recommended under Ventilation Rate Procedure with that required by their local code and to pick the most stringent. As for the project team's legitimate concern with energy efficiency, the "additive" Ventilation Rate Procedure adopted in the ASHRAE Standard 62.1-2004 reflects concerns for energy consumption with elevated ventilation rates. The recommended rate under the Ventilation Rate Procedure in ASHRAE Standard 62.1-2004, in many important occupancy types and projects can result in lower ventilation rates than those required by the earlier version of the Standard - Standard 62.1-2001."
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. procedure is absolutely allowed to be used if done correctly. The problem is that to correctly use it, you need to have an active contaminant reduction system such as gas phase filtration. Documenting the use of an assumed lower source material to meet this procedure is more than likely going to be rejected.
For your second question, the answer is that you should use actual occupancy and do not neglect the Rp variable. If you feel that the volume is so large that it dilutes the contaminants then do a short-term condition based on volume (paragraph 184.108.40.206), however I think you will find that it will not benefit you for such a small volume.
Andrew - Are you sure that this statement is correct, based on an actual LEED reviewer accepting 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. procedure on one of your LEED projects? For in the past they have categorically rejected the IAQ procedure (as of LEED 2.2) as I stated above, in 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 ID Number: 5053. I am really hoping you are correct, because I have an Engineer really wanting to use the IAQ procedure, but everything we find in the CIR database points to rejection.
Lawrence, I have never attempted to use 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. procedure on a LEED project. My comment is based on someone at American Air Filter telling me that they have used their gas phase filtration products to achieve the prerequisite and that the IAQ procedure would comply with LEED v3.0 since it is an acceptable means of ventilating a building according to ASHRAE 62.1-2007. If I were to attempt this method I would submit a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide and have a very well documented case for contaminant control. The documentation in 62.1 is very weak and I would not recommend using it alone. I would not assume that it is impossible based on a 6 year old CIR from a previous version of LEED.
I am using the "Offline Calculator" option to upload the 62MZCalc on LEEDOnline.
I noticed an input box requiring a narrative:
"For projects using ASHRAE 62.1-2007, provide a narrative describing how critical zones are selected and how all occupiable zones are accounted for in the determination of the critical zone. A critical zone is defined as the zone which requires the largest fraction of outdoor air in the primary air stream."
Any idea on what should be written here? My understanding is that 62MZCalc determines the critical zones automatically and accounts for it in calculating the required Outdoor Air.
The principles of LEED webinar for IEQ says "Project teams should choose several ventilation zones (these are DIFFERENT from thermal zones) per system in order to accurately determine which zone is the critical zone. [...] For a 10,000 square foot office 3 zones is usually enough to sufficiently determine the potentially critical zone. The calculator itself highlights the critical zone by turning the room title purple. DO NOT enter only 1 zone, this is not sufficient to determine the critical zone. " I think there is more information in the "directions" tab of the ASHRAE calculator supplied in the "credit resources" tab of IEQp1 in LEED Online.
Does your air handler have variable zone flow? Do some zones have heating coils that reduce the zone ventilation effectiveness to 0.8?
If so, you have the discretion to set these variables in the calculation, which can affect which zone the calculator chooses as the critical zone.
On our LEED submissions we are often entering every zone into the calculator and then tweaking the zone airflows to minimum heating positions to get critical zones calculated.
Once we've completed this task, we describe that process to let the reviewer understand why it was done.
It is feasible to simplify the calculation and enter less than every zone. ASHRAE 62.1-2007 Normative Appendix A has a systematic description of why this is possible and how you might go about picking which zones to enter in to the calculator. See "Selecting Zones for Calculation" section of Appendix A. That should help you understand why a zone is critical and give you a template for a potential response to the entry field you mentioned.
Kathryn & Aaron, thank you!
So I understand that if I enter ALL the zones served by my 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. in the excel sheet, I can be confident that the calculator will properly determine the critical zones and consequently the required ventilation rates?
I have 4 big AHUs in my project, each assigned to ~30-40 zones. The Engineers already inputted all the project zones into the respective sheets (4 sheets, one for each AHU).
The HVAC Engineers specified the AHUs (their supply / ventilation rates) as per the output of the ASHRAE Calculator.
Am I good to go?
an AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition)
2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. with no return air supplies 100% OA to an office and a conference room with FCUs, the OA supply ducts connected to the FCU supply ducts. can the entire system be considered a 100% OA system for both zones?
No, you should consider each FCU as a mixed air unit serving each zone. Also, it is bad practice to connect the OA supply to the FCU supply. It should be connected to the FCU return.
Andrew, many thanks. in that case, several FCUs serving one zone can be considered a larger sized single-zone system to make the calculation easier, can't they?
You can go that route and explain it in the form or you can divide them up into different zones. It's up to you but you need to explain what you are doing either way.
We have an apartment building with the valve air infiltration in studio, and also we have a mechanical bathroom and kitchen exhaust.
Can anyone please, clarify, how do we need to classify our project? Is this Natural ventilation, or a mechanical ventilation, or do we need to choose both options?
Please elaborate on the valve infiltration method. Can you provide a link for the product you plan to use?
So, this is the link for the product: http://www.flaktwoods.com/9fc438d3-d7ba-412e-9907-8543bd2b3fe4
These valves we set into the wall near the window for fresh air.
It looks like your design is based on a pressure differential from outside to inside. I think you would need to use the alternative compliance path to demonstrate how you are inducing the ventilation air since this is not technically a mechanical ventilation design and it also would not meet the free area requirement of natural ventilation.
Thank you for your response.
To clarify, I will start from the beginning.
So, we have:
1) A mechanical bathroom and kitchen exhaust. (fan-assisted)
2) A compensation exhaust air through valves infiltration (in studio).
3) We also have an openable windows (in studio), which meet ASRAE 62.1-2007 paragraph 5.1
How to classify our project?
If the window covers the studio under 5.1 completely then do natural ventilation for the studio. If the kitchen is part of that space then you would have no other mechanical ventilation. If the kitchen is separate and the exhaust is all you are using then do mechanical with an Ev of 0.5.
We are in the initial design of an office building. The Project team has planned to provide top hung window & the building will have more naturally ventilated spaces.
How to calculate the effective opening area / operable area to check 62.1 compliance & also the opening angle will vary based on its direction.
Is there any procedure or table to calculate the opening area considering the angle.
Also please let me know the same for side hung windows.
For an awning type window like you describe I have seen projects use 100% of the area that is movable and this was accepted by USGBC. I would not use this as the case if the window does not open at least 45 degrees. If it is less than that then you should do a geometrical representation to show what area you are using. That is how I would approach it.
For side hung (swinging) windows I believe they can open 90 degrees and thus 100% is definitely applicable.
How to do geometrical representation to show openable/operable area?. Because in our project, the angle is 30 degree. Please help to proceed further?
Is there any standard to follow at this kind of situation?
I would draw the window open in both plan and elevation view and show the actual area open to the outside. This would be a rectangle for the bottom horizontal plan and a triangle on each side for the vertical plane.
We have a mechanical ventilation system that continuously supplies
OA air into each apartment. Each apartment has a fan coil unit that conditions the apartment. OA is provided into the mechanical closet where the FCU mixes it with return air and delivers it throughout the apartment from a ducted system with ceiling or high side wall register. The toilet exhaust runs continuously. The LEED reviewer feels that because the FCU cycles to maintain temperature that the bedrooms are not getting OA when the unit is cycled off. (i.e. air will be short circuited to exhaust fan). Note that OA is entering the apartment via transfer grilles from the mechanical closet when the FCU is off. GBCI wants us to change our Ez from 1 to .5 to account for when the FCU is cycled off. Our supply is not close to the exhaust and changing the EZ will double our ventilation rate. We feel that ASHRAE 62.1 - 2007, Table 6.1 only requires outside air to be supplied to the dwelling unit and not to each individual room within the dwelling unit. We feel we have met the intent of 62.1 by providing continuous OA and exhaust from the apartment. What do you think - have we complied with 62.1? Do you agree with using the ,5 Ez (building is occupied so this one change will mean the project does not become LEED certified) Only other option is to run FCU continuously which tends to over heat or over cool the apartment and make it less efficient.
I would have to agree with USGBC here. I think they are being generous in allowing you to use 0.5 Ez when the fan is off. I think your best solution here is to allow the fan to run continuously while allowing the cooling coil and heating coil control valves to control to maintain temperature. I have designed many projects where I use this strategy simply because you have to comply with 62.1. If the bedrooms have openable fenestrations then you could use natural ventilation.
We have an apartment building in which we have both mechanical ventilation and natural ventilation. In a number of units the natural ventilation does not meet ASHRAE 62.1 for the open area or distance from the operable windows. As such we planned on breaking those apartments into zones supplied by natural and mechanical ventilation. The intent in the LEED program is to show apartments supplied by both mechanical and natural ventilation in both sections (mechanical and natural) with square footages for both equaling up to the total for that apartment. Based on some information found online it appears that if an apartment does not meet all of the natural ventilation requirements we are required to design the mechanical ventilation system as if the apartment has no natural ventilation available versus reducing the mechanically ventilated square footage for the area served by the operable windows. Are we allowed to enter the systems as indicated or do we have to design the system as if we have no natural ventilation?
I have achieved this prerequisite on many occasions using a mix of natural and mechanical ventilation in a single dwelling unit. I never mix the two in any single space but adjacent spaces separated by walls should be fine.
The questions is in regards to the LEED Reference guide for green building design and construction, 2009 Edition, IEQ Prerequisite 1 - Minimum indoor air quality performance (pg 407), Case 1 - Mechanically Ventilated Spaces states "Meet the minimum requirements of sections 4 through 7 of ASHRAE 62.1, 2007 Ventilation for acceptable indoor air quality". In ASHRAE 62.1 section 5.9, Particulate Matter Removal, it states "Particulate matter filters or air cleaners having a minimum efficiency reporting value (MERVMinimum efficiency reporting value.) of not less than 6 when rated in accordance with ANSI/ASHRAE Standard 52.215 shall be provided upstream of all cooling coils or other devices with wetted surfaces through which air is supplied to an occupiable space. The question is on Mini Split units (Wall mounted recirculating type with no outside air and Ceiling Cassette type with pre treated outside air) are these units required to have a minimum of a MERV 6 filter. My interpretation is that ASHRAE 62.1 is meant to provide a standard for filtering the outside air being brought into the building for ventilation. Therefore, if the dedicated outside air unit is filtered per ASHRAE, does the minimum MERV 6 filter rating apply to mini split systems which are really recirculating air and supplying pretreated/prefiltered outside air if any? Residentially Per ASHRAE 62.2-2010, ducted mechanical systems are those that supply air to a space that can be occupied through ductwork exceeding 10 feet in length and through a thermal conditioning component, except for evaporative coolers. Systems that do not meet this definition are exempt from this requirement. Also, mini-split systems typically do not have MERV-rated filters available for use and are, therefore, also exempted under this version of the guidelines. Commercially I could not find anything in which spells out the above for residential applications. Thank you for your time
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.
Do you know which LEED credits have the most LEED Interpretations and addenda, and which have none? The Missing Manual does. Check here first to see where you need to update yourself, and share the link with your team.
LEEDuser members get it free >
LEEDuser is produced by BuildingGreen, Inc., with YR&G authoring most of the original content. LEEDuser enjoys ongoing collaboration with USGBC. Read more about our team
Copyright 2014 – BuildingGreen, Inc.