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 received this question in IEQp1:
"The ventilation calculations indicate that the value of the flow rate of air projected under the condition tested (DS) was modeled as 100% level for each of the areas system; however the DS system is typically much lower for systems including 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. terminal units in the worst possible case. For the worst case, the DS can be determined for each area by dividing the minimum volume of the primary air VAV terminal during the worst possible case the peak volume of the VAV air terminal during the maximum cooling."
I'm working on a project, which has raised floor and fan coil air blowing underfloor. I've maded all analysis based on LEED Tool for multizones and considered the 100% Ds% in each zone.
How calculate this value "Ds%" for each zone?
I am working on a large project in Australia that has used local code. The local code is more stringent than 62.1 however needs to be documented for the submission. I was intending on working out some spaces which i deem to be worst case to show the outside air at the unit complies. However the LEED form asks for the required outdoor air intake and needs a baseline to show 30% better from. So I am wondering:
1) Has anyone documented the pre-requisite without doing the full 62.1 calculations to show equivalence
2) Has anyone documented the +30% credit without doing the full 62.1 calculations to show equivalence
Victoria, if you are complying with the more stringent requirements (which exceed ALL of the ASHRAE 62.1 requirements) then you should be fine with meeting the intent of the prerequisite and increased credit. That being said, meeting the intent, and documenting it are much different things. My recommendation is that you simply document using the ASHRAE 62.1 and LEED template. This is a much easier way to attain the credits since the LEED reviewers will be seeing the same thing they always do, and if you need to resubmit, you will be able to get more help.
A typical commercial kitchen has a large makeup air unit that provides air to a hood over the cooking surfaces, several exhaust fans, and (in our case) a large central cooling-only 0% OA 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. that provides cool air to the space.
I am puzzling over how to shoehorn this situation into the 62MZcalc spreadsheet.
Let's say I have 100% OA supply air at the hood of 1700 CFM, exhaust air at the hood of 2100 CFM. You can do the math and see 400 CFM of this exhaust air comes from "somewhere else" (Transfer air?). I am not sure how one handles transfer air in the 62MZcalc spreadsheet. Some fraction of the 1700 CFM hood supply air ends up in the kitchen, most of it gets swept up with the exhaust. 100% OA supply air is delivered at essentially room temperature, but right near the exhaust, so 100% Ez would not be appropriate.
What would you use for Ez zone air distribution effectivess? Would Supply air be "1700 CFM 100% outside air" in this case?
Would it be appropriate to use an Ez of 0.5, for "supply air near exhaust", counting the kitchen hood supply as the fresh air?
I've puzzled over the same thing before.
First, if the zones served are entirely commercial kitchen zones, my reading of ASHRAE 62.1 indicates the zones are only required to be exhausted, not supplied with outdoor air. I believe compliance with ASHRAE 62.1 is through satisfying the required amount of exhaust air (and making up the air per section 5), not by supplying a specific amount of outdoor air.
If there are non-commercial kitchen zones in the space (eg a managers office, active occupiable storage, etc), these would require their own source of outdoor air.
A second point - we have seen issues shoehorning 100% OA systems into the 62MZ calculator. The calculator is generally for systems that have some recirculated air; if the systems are 100% OA, then they may be documented either in the Appendices of the LEED EQp1 template (generally at the bottom, if the "100% OA" checkbox is selected) or in a custom spreadsheet. While it may seem counter-intuitive, in some cases we've seen the required amount of outdoor air increase when zones were first documented in the 62MZ calculator and then moved to a 100% OA calculator later. I believe this is because the MZ calculator uses equations that do not treat zone air distribution effectiveness in the same way as it is treated in the 100% OA system equations from 62.1.
Thanks, Aaron. I can find an entry for kitchens in Table 6-4 requiring exhaust, no entry for commercial kitchens (and other items from 6-4) in Table 6-1 requiring fresh air. It makes sense that exhaust would be the only requirement, but I haven't found a paragraph in the standard that just comes right out and says this. Maybe a sharper eye than mine can find it?
The closest I can find is paragraph 6.2.8 "... exhaust makeup air can be any combination of outdoor air, transfer air or recirculated air."
Yeah - I doubt the standard will have conclusive language that indicates "this and such space type does not require ventilation" - seems like it will be up to our interpretations of what the standard does say.
If you're looking at the 2007 version of the standard, I've relied on the language in section 5.10.2 to find the requirement that there be enough makeup provided to offset the exhaust, under certain conditions - "for a building, the design minimum outdoor air intake shall be greater than the design maximum exhaust airflow when the mechanical air-conditioning systems are dehumidifying."
I am working for a client who has a variable refrigerant HVAC system with a separate fully condition ventilator supplying fresh air. They are over budget and the contractor is proposing ducting the air into the back of the units in lieu of separate ducts for the ventilation system. We are worried that this would lead to them not meeting the LEED IEQ prerequisite. Would they not meet the prerequisite because it is already fully conditioned and not just a heat exchanger?
I am trying to understand how outside air loses effectiveness and would require more. In an effort to maximize the potential energy savings and minimize first costs (reduced unit size and main ductwork sizes as part of the shell package) the outdoor airflow quantity was based on a ventilation effectiveness of 1.0.
In this case that meant space delivered neutral air. If the air were ducted to the back of each unit it would be heated to a temperature that reduces the effectiveness to 0.8, thus requiring more total outdoor air.
Would this change of effectiveness hurt our chances of obtaining the LEED IEQ prerequisite related to ASHRAE 62.1?
Dustin, I believe you are correct. If the air is heated, the effectiveness would be reduced to 0.8. The outside air design requirement would need to be based on an Ez value of 0.8 instead of 1.0. You will need to update your calculations with 0.8 and see how much outdoor air is required with the new configuration.
Thank you Ilona. Would the change in effectiveness to 0.8 from 1.0 result in the loss of the LEED IEQ prerequisite? Would some sort of system change alleviate this issue and still maintain compliance with the prerequisite?
Dustin, I think you would have to run the numbers to confirm, but yes, if your outside air system was designed with an Ez value of 1 and you now switch to an Ez value of 0.8, you may not have enough outside air. This would hurt your chances of meeting the prerequisite. Your options are to a) ask the contractor to stick to the initial project design which requires direct delivery of outside air b), increase the volume of outside air provided by the AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition)
2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork.. If you are hunting for other options, I suppose you could try to change the supply air configuration to reduce temperature stratification. But at that point, you might as well just ask the contractor to install the system the way it was originally designed!
That's what I was afraid you would say. Thanks for your help.
Our project is located in Asia with a tropical climate. When we submitted our calculations for IEQp1: Minimum Indoor Air Quality Performance; the assessor came back with the following comment:
It appears that the calculations may not have been performed for the worst-case conditions. Generally, worst-case conditions are during heating mode;Provide revised Ventilation Rate Procedure calculations for zone air distribution effectiveness, Ez, of 0.8 (for an overhead distribution system in heating mode) and when the VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. system is at minimum flow.
My question is why we need to do calculations during heating mode as we do not use heating during any part of the year.
If your building does not have heating, then you just need to write a response to the reviewer that says your building does not have heating. An Ez value of 1.0 is appropriate if your system is only cooling.
However, if you have VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. boxes that vary the flow rate to the space, then you still need to make sure you evaluate the system at minimum expected flow rate.
Thanks for the info. Where do we input the minimum expected flow rate in 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. spreadsheet? is it Ep (Primary air fraction of supply air at conditioned analyzed) ?
If you have basic VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. boxes that modulate airflow from the air handling unit, then you would enter the percent airflow next to DS "Percent of total design airflow rate at condition analyzed."
Ep is only applicable for alternate systems such as induction units, where the supply air is a mix of recirculated air and primary air.
Thanks. Yes we do have VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. boxes and we had entered the percent airflow next to DS as 100%,since we are using VAV boxes & operated only by cooling mode.
so i am not sure of what the assessor means as "when the VAV system is at minimum flow"? do i need to need to change the percentage?where do i get that value from?
If you have VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. boxes, the supply air to your zone will only be 100% when you are at peak cooling on the hottest and sunniest day of the year when your space is fully occupied. During other times, say early in the morning or while the sun is blocked by clouds, your space won't need as much cooling. At that point, your VAV boxes will modulate to reduce the airflow to the space. Since the airflow to your space is reduced, the outdoor air to your space will also be reduced. That's why the reviewer wants you to evaluate the system at worst-case conditions. You need to determine the minimum setting on your VAV boxes and use that for the value of Ds.
Just to add to what Ilona said, the spaces that are not critical zones should be reduced as well. The 62MZCalc takes into account the unused OA that is recirculated from spaces that receive more OA than necessary. When those zones are reduced, the OA requirement is increased for the system.
Thanks Ilona & Andrew for your clarifications.
The VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. will be at the minimum setting when the occupancy load is less, as it is controlled by the CO2Carbon dioxide sensors. So if we require to do calculations when the VAV is set at the minimal supply, then do I need to alter my occupancy load too? Appreciate your help!
The VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. setting in the calculation should be altered based on the airflow to the room changing due to temperature. In almost all VAV applications, the aiflow changes based on a demand for more or less cooling. In the case of a cold day (no cooling load), and an occupied room, it is likely that you will be at minimum airflow and maximum occupancy.
Your calculation needs to represent your actual building use. If the above is not a true case then you need to write a narrative as to why it is not. In the past, I have had conference rooms on a middle floor in the center of the building (no envelope load) and have not decreased the supply flow since the cooling load is based on the occupants only.
So in order to compute the worst case scenario i understand that i need to change the value for Ds to reflect the minimum setting on the VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. box. Are there any other parameters that i need adjust in the 62MZCalc ? As i believe if i am going to change the Ds to a lower % the fresh air requirement will be more.Do i need to adjust the total design air supply too?
Forgive me for my ignorance. Thanks.
We are currently working on a project including an 100% OA 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 ventilation to 3 different areas.
The same people (110 people on peak) will be moving between those 3 areas during the day.
Using the table in the form for 100% OA is leading to a very large amount of outside air to provide since the number of people in each area for the calculation is 110.
Actually, we want to size the AHU to provide the required minimum OA for this zone composed of 3 areas and occupied by 110 ppl max. Depending on the need, the adequate volume of air will be directed toward each areas based on CO2Carbon dioxide sensors.
How are we supposed to document such a system in the form?
Thanks in advance,
Anyone with insights on this topic? Should just consider one single zone occupied by 110ppl?
You should input your three spaces with 110 people each (330 total) with a diversity of 33%. That will lower your OA requirement.
Andrew, thank you but there is actually no diversity as the Ahu1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition)
2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. will be 100% OA.
Ok. I thought that the 100%OA unit was providing preconditioned air to recirculating units. In that case, without demand contol ventilation or a recirculation mode, you will need to use the calculated flow.
If the areas will not be occupied often, and it's not an exhaust driven space, then it's a good idea to recirculate sometimes or use a time averaged ventilation rate.
I have a project that the system works with outside air demand according to the CO2Carbon dioxide sensor.
The outside air falls through a shaft and comes in line with the opening of the damper (opening according CO2 sensor).
What amount of air flow should indicate in IEQp1? The maximum flow passing through the damper?
I believe that the maximum airflow would be the correct value to use. The CO2Carbon dioxide sensor is designed to limit airflow when the space is unoccupied, and not needing any outside air. ASHRAE 62 vbentilation rates are based on maximum occupancy. The CO2 sensour is designed to sense maximum occupancy and turn on the outside air at that time, so it would make sense to analyze the peak airflow through the damper.
We are working on a residential core and shell project, and we are having some issues with the compliance of ASHRAE 62-1 ventilation requirements.
Basically, the building has apartments on each long side and a central corridor that goes all the way through.
All of the rooms include a operable window of 4% of the area within 25 feet, except a small service room that would only have a window to the corridor; therefore it would be ventilated through the adjoining space. Now, this central corridor is completely open to the outdoors on its sides; could we use the 4% rule, or do we need to go with 8% or 25ft2 minimum? The problem is that a 25ft2 window on that tiny space would be unreasonable.
Thank you for your comments.
Is the 'service space' an occupiable space that requires ventilation under ASHRAE 62.1? If it is a mechanical closet or non-occupiable storage closet, you may not be obligated to provide ventilation.
Yes, it is actually an occupiable space that requires ventilation,
The need to keep FTEs consistent through all credits is stressed though in the case of IEQp1 where for Mechanical Ventilation, table IEQp1-3, for code compliance based on square footage, the Pz (zone population) numbers provided by our Mechanical Designer are far greater than those anticipated for FTE.
In reality, the ventilation system is designed to meet code for far more occupants than will ever be expected. I am wondering if this inconsistency would flag consideration by a reviewer.
FTE=86, Total Peak Occupants = 226.
The requirement for FTEs to match goes back to an error made by the LEED v2 Reference Guide authors. The error creates a huge loophole for projects that do not actually meet the requirements of ASHRAE 62.1. It has been more than 10 years and the error still exists. Based on my 15 years of working with the USGBC, and 4 years as the vice-chair of the IEQ Technical Advisory Group, it will never be corrected.
Engineers should NEVER use LEED calculations as the basis for sizing a ventilation system. That would create a design liability problem.
For a 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. (multiple-zone) system should the Design System Primary supply Airflow (Vpsd) sum up the total supply (and not the outdoor) air of each zone? Accordingly, should the Vdzd figure for each zone of a multiple-zone system reflect the supply airflow of that particular zone?
If this is the case, the Vpsd figure should match the Supply Airflow figure entered in the EAp2 Spreadsheet – Table 1.4.7B.
Is the assumption described above correct? Thank you in advance.
Does anyone know how ASHRAE defines a "kitchenette" from a regular kitchen? I am trying to determine which value I should use from Table 6-4 of 62.1-2007. I know NYC code defines a kitchenette as less than 80 SF, but I didn't see any definition on 62.1 or 62.1 User Manual. Thanks!
ASHRAE does not define what a kitchen or a kitchenette is. Generally, if a small kitchen does not have an oven, and it is small in area, it can be called a kitchenette.
In a kitchen, you can do full food preparation because there is not enough room to do that; the countertop area is too small. In a kitchenette you basically store and reheat precooked food, or cook very simple meals.
I disagree. Kitchens and kitchenettes both have ovens. A kitchenette is not the same as a break room that requires outdoor air. Kitchenettes have small residential style ovens (usually just one) and kitchens have industrial equipment for mass food production. If you have a small room for food preparation (eg. with a microwave), I would consider it a break room and not require exhaust but require outdoor air.
Well I disagree back. Kitchenettes do not typically have ovens. The reason you need additional exhaust in a kitchen/kitchenette is to control humidity (5.10.1, Exception). Kitchens that have industrial equipment should be considered commercial kitchens.
ASHRAE does not define the differences between kitchenettes, kitchens (residential), or commercial kitchens, but each of these require a different exhaust rate in the standard. You are left to your own to figure these out, but an oven does increase humidity so should require special exhaust which is not required for a simple break room.
If humidity control is the method to evaluate wether or not to exhaust a space, then the table shows us that kitchenettes have ovens. Both need exhaust per table 6-4.
But humidity is not the criteria because 5.10.1 exempts kitchens from humidity limits.
Ovens in kitchens and kitchenettes produce significantly contaminated exhaust. Microwaves in break rooms dont.
Notice that showers dont have exhaust requirements.
Hernando, Rudolph, thank you for your responses. To clarify, my project in question are apartments, so the "Residential Kitchens" category is most applicable, but I was curious if ASHRAE clearly delineates kitchenettes like NYC code does. Seems like it doesn't, so it appears it is left to our judgement to determine which category to use.
Humidity is the criteria to determine whether a kitchen rate applies. Humidity is not a criteria for break rooms. If a break room has a microwave it should be okay to claim the space as a break room. If a break room has an oven or range top cooker, then use the ASHRAE required exhaust rates.
Microwaves do create odor and generate humidity. This is easy to observe if you wrap a meal in a ceramic container with clear plastic, like Saran Wrap. The wrap traps in the moisture, and if you open it after the food is cooked it releases a lot of steam (humidity). I believe it is okay to exclude microwaves from exhaust requirements because they not heavily used in break rooms.
In terms of showers, I have yet to see a project that did not include exhaust in shower rooms. ASHRAE 62.2 has an exhaust requirement for bathrooms. Bathrooms are any room containing a bathtub, shower, a spa, or a similar source of moisture. Controlling humidity in moisture generating spaces is not a requirement, as you noted.
Use your own judgement. Just be aware that the LEED reviewers might question your assumptions. Make sure your assumption are reasonable, and logical, and make some references to the ASHRAE Standard.
What is "the local jurisdiction approval"?
You know what this is? How do I get this approval? With the designer?
I've worked in other certificate were accepted sizing calculations showing the natural ventilation system only.
1) Show that the project complies with local jurisdictional, minimum ventilation requirements, if the local requirements exist.
2) Show that the project complies with the LEED/ASHRAE minimum ventilation requirements.
Since the project complies with both LEED and local requirements "whichever is more stringent" is proven. There is no reason to compare the two sets of requirements to each other.
The situation I have is that I have a project of a warehouse where there is natural ventilation in coverage.
This ventilation is "Enginnered Natural Ventilation System".
I showed all sizing calculations, and was asked about this approval of jurisdiction.
This ventilation is an exception from section 5.1 of ASHRAE 62.1 but do not know how to prove this, since the document submitted is the natural ventilation calculation description, considering all of the local climate parameters.
I need to ask something the ventilation designer, or just explain better what was considered?
You can compare the design air changes per hour (ACHAir changes per hour: The number of times per hour a volume of air, equivalent to the volume of space, enters that space.) to the Vot (zone outdoor air flow) calculated using the ASHRAE 62.1 calculations: Sections 6.2.2 (Vbz = [Rp x Pz] + [Ra x Az]; and then Voz=Vbz/Ez) and either 6.2.3 (Single-Zone) or 6.2.4 (100% OA). Vot will likely be equal to Voz.
Your Ez is probably 0.8 (see ASHRAE 62.1 Table 6-2). It might be 1.0 but claiming a lower Ez helps avoid further questions from the reviewers.
Ok! Now i know how to prove this. This helped a lot.
I am trying to understand the VRP Compliance Calculator at the end of the template. I have completed the 62MZCalc spreadsheet, and it comes up with one answer for 30% increased ventilation. Our project complies with this number. If I enter data into the VRP Compliance Calculator, it spits out a larger number for 30% increase, and our project does not comply. Is this VRP Calculator required if one has already proved compliance with 62MZcalc? Under what circumstances is it mandatory to use it? Is it optional?
Unless the ventilation efficiency of every zone served by a system is identical the OA required will not be 30%. The total OA is driven by the zone that has the lowest Evz. If one zone has an Evz of 0.80, and all of the others an Evz of 1.00, the ASHRAE standard uses the 0.80 value to determine the OA. The zone with the 0.80 Evz is the critical zone.
Check to see what the range of values of your Evzs are. If they are far apart then the ventilation flows to each zone need to be adjusted. One solution is to rebalance (redistribute) the airflows to the zones. Take reduce the ventilation air to the highest Evz zones and use it in the lowest Evz zone.
Sorry, I am not quite sure the question was clear. We are trying to achieve the IEQc2 30% increased ventilation credit. (This hasn't got anything to do with 30% outside air, it has to do with achieving the IEQc2 Credit). According to the 62MZcalc spreadsheet, we comply. Is the "VRP Compliance Calculator" located on the IEQp1 Template a required submittal or is it optional?
To achieve EAc2 with 30% OA at the zone level you will require more than 30% OA intake at the system level. The further away you are from 30% at the system level, the more out of balance the zones in the system are.
It's my understanding that if you're using the 62MZCalc spreadsheet you do NOT have to do the VRP Compliance Calculator or complete Appendix 1 of the LEED Credit Form. You upload your 62MZCalc files, fill in the end result values from 62MZCalc into Table IEQp1-2 on the LEED Credit Form for the "Offline Calculator," and I believe the only "logic" it has built in is simply the Yes/No evaluation -- no math, and no entries in Appendix 1.
Let us know if that doesn't work for you.
I'm a little confused about a review comment we received. We have rooftop AHUs supplying 100% Outdoor Air to multiple zones equipped with terminal fan coil units. The terminal fan coils mix the OA with locally recirculated air to meet heating and cooling requirements.
We used the 62MZCalc form to document compliance with ASHRAE 62.1 since it is a multiple zone system. Per the reviewer's comment, we cannot do this as the system is 100% OA.
However, the LEED form itself does not allow you to factor in diversity at the level of the AHU. This is a university building with a mix of uses and occupancy schedules and so it will never be 100% occupied at max occupancy. Will LEED reviewers allow you to use a population diversity factor when working with 100% OA systems?
The ventilation requirement has to be satisfied for each individual space. Therefore, if you are not recirculating "unused" outdoor air from some spaces, it doesn't seem that population diversity would be relevant for the individual room calculations. You would need to provide enough outdoor air through the 100% outdoor air system to satisfy the ventilation requirements for the design occupancy in each space.
For airflow at the AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition)
2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. level, if you have a way to reduce or shut off outdoor air to individual spaces when the room is at reduced or no occupancy (such as shut off or modulating dampers on the outdoor air duct to the room controlled by CO2Carbon dioxide sensors and/or occupancy sensors), then you could explain that your design cfm for the 100% OA AHU does not need to add up to the full OA design cfm sum of all the spaces due to occupant and scheduling diversity. If the LEED form does not provide for this, you can provide your own calculations and explanation under the Special Circumstances section.
Thanks! That is exactly our scenario - we have demand controlled ventilation and so airflow is adjusted to meet occupancy levels.
In our high-rise multifamily building project, we are trying to demonstrate IEQp1 compliance for living rooms & bedrooms by showing an engineered ventilation system whereby toilet exhaust fans draw enough outside air through operable windows in said rooms to satisfy 62.1 rates. However, the LEED reviewer is asking for documentation on how the required ventilation rates would be met when the windows are shut closed. From my understanding, simply having operable windows is sufficient to demonstrate 62.1 compliance, and since the windows can be opened or closed by the occupants when needed, it is not necessary to show compliance with windows closed. Can anyone add their thoughts on this? Thanks!
There are two paths for showing ventilation compliance for an individual space or ventilation zone:
Path 1 - Mechanical ventilation. In this case, you cannot take credit for opening windows. And this is where ASHRAE 62.1 mechanical ventilation rates apply.
Path 2 - Natural ventilation. In this case for NC2009, operable windows are sufficient, subject to area and distance requirements for the windows. You could probably make a special circumstances or alternative compliance case for extending the distance from the window due to the assistance of the toilet exhaust fan, but ASHRAE 62.1 ventilation rate do not really apply to the natural ventilation case.
I think you will get more traction by clearly identifying which path you are taking (either Mechanical Ventilation or Natural Ventilation) and sticking to that path. If you blend the criteria for the two paths together indiscriminately, it will be unlikely to be accepted.
For example, you could say for Alternative Compliance that you are using the natural ventilation path, show that you have the required percentage of operable window area, and then introduce the concept of "fan-assisted" natural ventilation to justify any areas farther than the 25 feet criteria away from the window.
We are working on a office building in which there is an openspace. The outside openings largely cover 4% of the total floor area. A small part of the open space areaOpen space area is usually defined by local zoning requirements. If local zoning requirements do not clearly define open space, it is defined for the purposes of LEED calculations as the property area minus the development footprint; it must be vegetated and pervious, with exceptions only as noted in the credit requirements section. Only ground areas are calculated as open space. For projects located in urban areas that earn a Development Density and Community Connectivity credit, open space also includes nonvehicular, pedestrian-oriented hardscape spaces. falls outside the distance of 7.6 m from the openings. For this part of space I have to provide an engineered ventilation dimensioned only on the area that falls beyond 7.6m? Or the engineered ventilation system shall be sized on the total openspace area?
I am working on a project which has an employee locker room, where truck drivers will come to change or shower after their shifts once a day. It isn't a heavy-use locker room like you'd find in a school. I'm not finding any spaces in ASHRAE 62 Table 6-1 that look very similar to this usage. What would be a reasonable People Outdoor Air Rate and Area Outdoor Air rate for such a space? The ASHRAE 62 Users Manual Table 6A might also shed some light.
After studying this for a while, I've understood that areas in Table 6-4 may simply require exhaust but no outside air. I haven't found anything in the standard that just comes right out and says that spaces requiring exhaust don't need any fresh air (perhaps a sharper eye than mine can find it?) however the spaces in table 6-4 requiring exhaust are not listed in Table 6-1. The IEQ Space Matrix from USGBC does list locker rooms as spaces requiring compliance with ASHRAE 62, but doesn't provide any more guidance.
Failing that, I could probably argue that the space should recieve 0.18 CFM/sft, and 10 CFM per person, among the higher rates int he table, as well as the required exhaust. I am not sure that would be the right approach.
We are working on a small building that will operates for conferences and private events.
There will be a kitchenette or coffee point (only microwave, coffe maker and refrigerator). The space will not have exhaust air since no food will be prepared in it.
For the purpose of this prerequisite, would be acceptable to provide recirculated air from the corridor to the Coffee point in order to satisfy the requirements of the Minimum ventilation rate?
Ie, does Ashrae 62.1-2007 requires that outdoor air is supplied directly to each single space or it allows the use of recirculated air, not mixed with any outdoor air?
I' m currently working on a school project where most of the corridors have an exhaust system, that induces make-up air from the adjacent classrooms and (eventually negligible) infiltrated air directly from outdoors (due to windows permeability). Does this situation allows to comply with ASHRAE 62.1 outdoor air requirements for corridors, consideringa a ventilation distribution efficiency of 0.5? Should all the transfer air be considered as outdoor air, or only the "excess" (outdoor air supplied in classrooms that exceed its outdoor air requirements) outdoor air portion of the total transfer air? Thanks.
I'm working on a distribution center project that intakes the air by docks and exhusts it through fans in the roof. Is it natural or mechanical ventilation?
Another question concerns the ASHRAE requirement which says that Air Intake Minimum Separation Distance from the truck loading area or dock should be 25 feet. In my case it's impossible as the dock is the air intake. Is there any exception to this requirement?
What is the difference between storage room and warehouse in table 6-1 of ASHRAE 62.1-2007? Storage rooms need twice the ventilation required for warehouses. Is it correct to say that the difference is mainly in area, storage rooms being smaller and warehouses being larger? Both spaces are marked with a "B" meaning that the ventilation may depend on the type of material stored ("rate may not be sufficient when stored materials include those having potentially harmful emissions.").
Thanks in advance!
The difference is area. Warehouses are meant to have a lot of operational space which decreases storage density.
Another factor is that a warehouses' vertical height is much greater than for storage rooms and therefore air from chemical contents in storage rooms more quickly saturates the air with polutants. Read the section in ASHRAE 62.1 on time averaging.
Andrew: do you know if GBCI has incorporated time averaging into the v5 IEQP1 template?
Its obvious to me that they have not since there is no room height input.
I think you answered your own question correctly. They do not have inputs for room height or occupancy schedules. The time average is only useful for spaces with high intermittent occupant loads.
Andrew: I think It's usefullness is directly related to how much an owner can save yearly when reducing OA rated by 10 to 20%.
I am seldom involved in a project that does not have any intermittently 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.. But even so, a space that isnt intermittently occupied should also be time averaged. Offices spaces for example can get close to 10% reduction in OA flow rates when time averaged.
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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