EBOM 2009 IEQp1: Minimum Indoor Air Quality Performance

Here are some ideas.

1. Any system that is providing outside air into 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. needs to be included in the calculations. Generally exhaust systems are not included but one exception would be if the exhaust system is the sole source of outside air into a space.
2. Yes, you need to do a separate 62MZ spreadsheet for each system. Only potentially critical zones need to be included in the spreadsheet but you will also need to complete the "Inputs for System" section of the spreadsheet, which allows the calculator to determine the outside air required for the entire system, not just the critical zones. This value for required outside air, for the entire system, is then transferred over to the LEED submittal form.
3. In version 4 of the submittal form, there is a check box to select to complete the ASHRAE 62MZ calculator. Checking that box will automatically pull up the table that needs to be completed on the form. You don't need to complete the table in the submittal form appendix if you do the 62MZ calculators.
4. With the version 4 form select the check box that indicates you have areas served by natural ventilation. Then you will need to complete the natural ventilation table in the submittal form appendix.

With regards to Natural Ventilation in 62.1, ASHRAE defines occupied floor area as "an enclosed space intended for human activities, the term occupiable space excludes those spaces intended for other purposes, such as storage rooms and equipment rooms that are occupied only upon occasion and for brief periods of time." I'd say that because corridors are not specifically excluded it would be safe to have operable windows within 25 feet.

If you are using version 4.0 of the form, you'll need to enter each AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. as a separate system in the appendix. For this form, each zone must be listed and the population and area should match up with known values for each zone.

If you'd like, you can use the ASHRAE 62MZ calculator and complete a separate calculation for each AHU. This calculator allows you to assess the critical zones of each system to determine the total outside air required. In other words, each zone does not need to be individually entered into the calculator.

If you are working with any version of the form other than version 4.0, you'll either need to request the updated version of the form or use the 62MZ spreadsheet.

Yes, you can manually measure AHUs as stated above. We have used this method on LEED EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. projects. Is the DOAS constant volume? For variable volume systems you often have to use the minimum air flow setting.

There's a couple of things going on here.
1. If for some reason you needed to make corrections to the the ventilation system in order to meet the ventilation prerequisite during the review process, you could do so without having to re-set the performance period for all of the performance based credits like EAp2, purchasing credits, MRc7, etc. Though, you would have to re-do the outside air measurements. It is also probably worth confirming this with the project review team.
2. You can still use the 62MZ Calc to calculate the minimum required outside air. That calculator only requires assessment of the critical zones and is an acceptable alternative to using the credit form calculator. So, you can still avoid entering in hundreds of zones.

"Worst case" to me means all 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. zone dampers at minimum position. Is there some alternative?

I suppose you could make a case in certain spaces that the zone damper would not be at minimum when the space is fully occupied due to the heat gain from the people. I would explore that avenue if some spaces were troublesome at minimum damper position.

Thanks for the response Julia.
Here is the issue I am having a problem with:

The LEED reference guide states that 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 must be set to worst case conditions. If the measured outside air rate during worst case conditions can not meet the ASHRAE 62.1 specified rate then Case 2 must be checked on the LEED Online template. The LEED reviewer has asked me to me to provide a summary of air measurements taken at maximum flow conditions. (this request also appears on the LEED template)

So which is it???
Take measurements at worst case conditions or maximum flow conditions?

Another LEED reviewer on a different project asked the following: provide technical evidence confirming that this limitation is true for all system operating conditions.

Of course it's not true during all operating conditions!
Only during worst case conditions!!

Any direction is greatly appreciated.

David - leaving the confusing (and varied) review comments aside, I think the critical terminology is 'worst case' under 'normal operating conditions'. So as I read it, that means the dampers at the minimum position they would be set for a given occupancy. In some instances, occupancy will be relatively fixed and its simply minimum damper settings. But for many systems, there is interplay between occupancy and damper settings (as Julia references in talking about heat gain). So worst case normal is a bit of a moving target that has to consider both variables in dampers and in occupancy. As for maximums, I'm pretty sure the template doesn't ask for measured airflows at maximum flow - it may ask for the design maximums but the only measurements required are the worst case normal we were talking about. Measuring maximum flow doesn't really tell anybody anything useful, unless the question is determining the ability of the system to deliver ASHRAE ventilation (making the ASHRAE vs 10cfm/person distinction).

And I suspect the second reviewer comment was simply confirming that what you said was worst case normal really was 'worst case'. Its possible that the OA rates were so high as to make the reviewer wonder if that was really worst case. Perhaps not the most direct way to ask that question, but that's my theory.

Hope this helps a little - I suspect other folks may have more technically savvy insights. . .

Dan

Thanks Dan. That helps.

Moving forward I will instruct the TAB contractor to put the system into worst case condition (i.e. 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. dampers set to minimum positions + highest expected occupancy at that moment in time) when taking the outdoor air measurement. Compare the outdoor air measurement with my ASHRAE 62.1-2007 calculation. If the referenced standard can not be met we'll follow Case 2, 10 cfm/occupant.

Thanks again!

To build on what Dan said, "worst case normal operating conditions" are typically encountered on peak heating days (for which you can also use the design heating day). In that case, recirculation is maximized to limit heat loss, so outside air damper position is minimized, while 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 are typically also minimized. (Peak cooling day is not quite as extreme since usually more air is delivered to offset zone heat gains, meaning VAV boxes would be slightly more open.) So I would recommend simulating the peak cooling day for the air testing.

If you are utilizing an alternative compliance path check the appropriat box under the ADDITIONAL DETAILS heading. Project using this approach will be reviewed on a case-by-case basis.

Table 6-1 of ASHRAE 62.1-2007 requires warehouses to be provided with 0.06 CFM of outdoor air per square foot during occupied hours. Project teams must account for both people and area when calculating outdoor air rates.

For the EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. rating system, I believe that for each piece of equipment that you determine is not capable of fully meeting ASHRAE 62.1, you have the alternate option of documenting that you have at least 10 cfm/person. I do not recall anything in the alternate option about accounting for square footage. This makes sense to me, because most existing buildings were designed when ventilation rate charts were based on occupancy for most spaces, and not floor area.

Table "Case 1: ASHRAE 62.1-2007 Ventilation Rate Procedure" auto-calculates Rp, Ra, Vbz, Voz, and Vot.

If you are are using a different calculation / spreadsheet to show compliance check the "The project team is using an alternative compliance approach in lieu of standard submittal paths" box under the ADDITIONAL DETAILS heading on the template.

The prerequisite requires applicants to demonstrate that each outside air intake, supply air fan, and/or ventilation distribution system supplies the minimum outdoor air ventilation for each air handling unit.
I would expect the LEED reviewer would ask you for OA measurements at every 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..

The LEED online template requires the reading to be taken during the performance period.

Hope this helps.

Does this mean that for compliance with IEQp1 we will need to demonstrate calculations (from ASHRAE 62.1) that show the required OA rate, AND take measurements at each AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. utilizing the OA proving that we meet the calculated rate? Or would it be sufficient enough to take measurements at only the units supplying OA (i.e. if you have a large MAU that distributes ventilation air to multiple FCU's, do you need to measure OA at each FCU or simply measure the OA supply at the main MAU?)

LEED requires OA measurements to be taken at the system level. If you have a large make-up air unit that distributes OA to numerous fan coil units you will need to take OA measurements at each fan coil unit. i.e. the fan coil units are considered to be "the system level".

Monthly screen shots, during the performance period, showing the fresh air damper is open during occupied times and closed during unoccupied modes would suffice. Or, provide a narrative from the responsible party stating they have used the BAS system regulary to ensure that fresh air dampers are operating in accordance with the documented sequence of operations.

The intent is to verify the ventilation system is working correctly during the performance period.

Hope this helps.

Just confirming... Does this mean that if there is a BAS in place that already in place that measures OA, CO2Carbon dioxide, airflow etc, no physical testing or balancing 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./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. level has to be conducted unless an issues comes up that it does not meet the 62.1 levels? Thank you in advanced

The prereq requires an airflow measurement.
CO2Carbon dioxide sensing of RA and OA will not suffice.

sorry :(

You do not need an ERV for EA P1 compliance.

If you are mechanically ventilating the space calculate the required fresh air volumes per ASHREA 62.1 section #6. Each of the split systems will most likely be provided with an 8" diameter outside air duct.

If you are naturally ventilating the building follow the requirements of ASHRAE 62.1 section #5.1.

Hope this helps.

David,
Thanks! Could you also tell me if measurements can be made just once during the performance period or if they have to be continuous to verify we met the OA flow rate?

Janna,
You'll only need to take the OA measurement once during the performance period. If you provide permanant continous monitoring you may be able to achieve IEQ C1.2 - Outdoor Air Delivery Monitoring.

David,
In your response above when you said "You do not need an ERV for EA P1 compliance", did you mean to say IEQ P1? The prerequisite reads outside air intake must meet standard for all normal operating conditions, but what about when the HVAC system is off - like during mild spring or fall weather. That is what made me think we might have to have an ERV system. But I like answer of "no we do not".

Does natural ventilation have to be provided by permanently opened "windows" or could I complete calcuations based on the windows that can be opened by occupants when necessary.

I meant to write IEQ P1, thanks for the clarification.

Even during milder weather days you will still need to provide fresh air in the quatities outlined by ASHRAE 62.1 during occupied hours. On milder days HVAC systems typically operate in the economizerAn economizer is a device used to make building systems more energy efficient. Examples include HVAC enthalpy controls, which are based on humidity and temperature. mode.

For natural ventilation systems the wall or roof openings do not need to be permanantly open. They do however require control such that occupants can easily open them when the space is occupied.

LEED EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. only requires ventilation to be met at the system level, not the zone level. Measuring the OA rates at the two AHUs to verify compliance with ASHRAE 62.1 will suffice.

Be sure to stay consistent with the 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. count of the project.

Can you provide further clarification on what you mean by staying consisten with the 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. count of the project. Are you suggesting for IEQp1 we should be consistent with occupancy counts for both ventilation and say plumbing calculations (I've only heard of FTE in reference to water calculations).

Thanks in advance David!

The System Ventilation Efficiency factor (Zp) of the Ventilation Rate Procedure is not correctly accounted for if you do not consider the 26 recirculating AHUs. The method for completing this calculation also strongly depends on whether the AHUs are CV or 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..
While measuring the OA rates is sufficient at the system level (in your case measure OA rates at each AHU providing OA), you'll need to more accurately determine the zones for each OA AHU to correctly calculate minimum OA requirements per ASHRAE 62.1-2007 Ventilation Rate Procedure. These zones will depend on the air distribution system, partition walls or any air barriers, and loads in the space.

My understanding is that this issue comes down to whether or not the area can be considered a single ventilation zone, since it appears Zp only needs to be accounted for in Multiple-Zone Recirculating Systems. The sales area I am calculating ventilation rates for has similar occupancy category, occupancy density, distribution effectiveness and primary airflow per unit area. Although there are many "occupiable spaces", by definition, ventilation zones can have one or more. The air distribution system is a ceiling supply of cool air, and while there are aisles, the length of the space between the top of the aisles and the ceiling is large enough where it doesn't seem necessary to consider the aisles air barriers. That all being said, I am inexperienced working with this standard, so please let me know if something in here is incorrect.

For what it's worth, and I'm not sure if it is possible to take this into account, because I'm treating the whole area as one zone, the recirculating AHUs will be working as a CV CO2Carbon dioxide demand system, controlled by the building automation system. Since the area is very large, and it is probable that at certain times customer population density will fluctuate from store area to store area, depending on special sales or other retail related factors, this will move the fresh air to where it is needed if the circumstance requires it. The fresh air AHUs, however, will be constantly providing the calculated minimum outdoor airflow volume sufficient for the entire ventilation zone.

So, I guess the fundamental question is, do you think I can I consider the sales area to be one ventilation zone?

Thanks

Yes, I would agree with your logic.

In my experience, it shouldn't be a problem taking the approach you describe. But, just in case you didn't know, air balance reports for the exhaust systems would certainly qualify, but teams often show compliance with much less intensive documentation, such as PM logs that verify fan speed, voltage, etc.

Hi Jenny, one more question. For the measured outdoor airflow for each zone, would it be okay to grab this information from our Building Automation System? Or would it have to be something that we need a formal reporting protocol such as getting a Flow Hood and getting the reading from each individual zone.

Let me know when you get a chance thanks!

I am a bit confused by the wording of your question, but I'll try to answer based on my understanding. The requirements for this prerequisite involve ensuring that the HVAC system can meet the needed ventilation loads of the space. If it is an office space, the HVAC should be able to meet the needs of that space as designed (with occupants), not as it currently stands (vacant). In your case I would come up with reasonable occupancy numbers for the vacant floor based on numbers from other floors.

I want to make sure I'm understanding this correctly...

Even if we have a vacant space, we should use the default space type density to assume that we have occupants in the space. Then we should calculate our required ventilation based on the default occupant density even though the space is vacant.
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With that being said, since during the performance period we are only required to take one measurement of the outside air, if we are able to show that 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. for that vacant space can supply sufficient OA, are we able to return the space to "unoccupied (i.e. shutdown OA to vacant space) to save energy? Basically it seems to me that we should be able to demonstrate that the system can supply enough OA if it were occupied, without actually having to do so since the space is vacant.

Yes, per page xxiii of the LEED-EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. Reference Guide, all prereqs and credits except IEQp2 are subject to the 10% exemption option.

Hi Pablo,

This will all depend on your review team, as each is different. Decisions handed down in one case will often directly contradict decisions handed down in others. All I can offer you is my experience, but i cannot promise that it will be identical to yours.

We submitted our 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. measurements for this prerequisite and were told that the project team had misunderstood the meaning of "worst-case conditions as it relates to EQp1." We thus re-tested over a third of our units at the proper worst-case conditions AFTER the performance period and preliminary review stage, and our project was ultimately approved for LEED certification.

I don't know if this experience translates exactly to your case, as it seems that in your situation the building was not receiving the required minimum of outside air during the performance period, if I'm interpreting your comment correctly (whereas ours was, we just didn't prove it in the right way).

Hope this helps.

Pablo - My experience as a reviewer is consistent with Patty's. Although the goal of the prerequisite is (at least partially) to ensure that your EAp2-related energy efficiency was not achieved at the expense of reasonable ventilation rates, in reality the GBCI has been understanding that the EQp1 calculations are not easy to get right, and projects may either miscalculate or accidentally under-ventilate. I can't recall any project that I was involved in being rejected on EQp1 grounds if they were ultimately able to achieve the required OA rates, even if that achievement was not documented (or did not occur) until after the performance period had concluded. Ultimately, the GBCI wants the review process to improve building operations for the future, not solely evaluate operations in the past.

I'm confused about this issue as well. If LEED expects users to complete the spreadsheet why is it not given as an option to upload? The table on LEED Online doesn't allow as much detail as the ASHRAE spreadsheet, so I am certainly confused as to what LEED is looking for here...

Interestingly, this issue has recently cropped up on a pair of my projects as well, and been equally frustrating. Here's what (little) insight I can offer - the compliance model for this credit has historically been for projects to complete the 62MZCalc spreadsheet for each AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. in the building, and then upload ALL of the completed calculators. The information in the spreadsheets was also required to be transferred to a simple table that identified each AHU, the required OA, and the measured OA. This made sense but required a lot of individual uploads/downloads for projects and reviewers. More recent projects, however, do not seem to be required to provide the 62MZCalc spreadsheets - they are simply expected to populate a revised LEEDOnline table/calculator, which ostensibly mimics/simplifies the 62MZCalc into just a handful of inputs. So there are two questions here: 1. Can we provide a pile of 62MZ calculators in lieu of completing the table, and 2. What if the 62MZ calculator and the table generate different results for a given AHU (because of the lesser level of detail).

1. I feel like the answer to this is no - if you've completed the 62MZCalc spreadsheet for your building, you've already done 95% of the work. Transferring the key data into LOL is a headache, but it also eliminates an enormous headache for the GBCI reviewer. It's not uncommon for that table to be dozens of rows (although thousands would be a first for me).

2. The table on LOL should capture all the key elements of the 62MZCalc in one simple format. If for some reason it fails to accurately describe your building or a specific unit, I would use the alternative compliance path option to explain your situation and upload your 62MZCalcs.

Ultimately, GBCI is looking for a simple, clear way to understand compliance with what is admittedly a complicated standard and calculation. Hopefully the table in LOL is a step in that direction, but if it is creating more problems than it solves, explain how/why to the reviewer and provide your 62MZ calculators to back up your case.

ASHRAE 62.1-2007 is mostly concerned with ensuring the interior spaces are receiving enough outside air under the worst-case normal operating conditions. Worst-case conditions are described as those when the least amount of outside air is being delivered (e.g. dampers squeezed down to their minimum openings). If these supplemental units installed by the tenants are never off, then it would be wise to test them -- it would help show that the minimum requirement of outside air is indeed being met for those spaces.

However, if the supplemental units are not constantly on -- for example, if the unit is an AC window box that is only used in the heat of the afternoon -- then you do not need to test the supply CFM. Worst-case conditions in this case would be a cold day when the tenant decides not to use the AC. It is on days such as these that ASHRAE wants to make sure the interior spaces are getting enough outside airflow.

We've seen cases where the LEED reviewers interpreted this situation differently from local code officials, who were also following ASHRAE 62.1 language to determine the ventilation provided by operable windows and the distance of compliant spaces.

On a residential project pursuing LEED NC 2.2, we had a similar condition to yours where a back room without windows had a large opening to a front room, and the front room had operable windows for ventilation. Most of the back room was beyond the 25' distance from the front room windows. For local code compliance the back room was considered adequately ventilated, but the LEED reviewers indicated any area beyond the 25' would not be considered adequately ventilated. We were able to comply with LEED requirements by providing a small transfer fan between the front and back rooms that would mix the air of the front room with the back room.

To your question, since this was an NC project and under 2.2, it may not predict exactly how your situation would be reviewed, but may give you an idea how it has been interpreted in the past.

Then, if only the interior space (adjoining a room with a direct opening to the outdoors but not within 25 feet distance from th windows) is supplied by a dedicated fresh air system (fresh iar fan blowing fresh 100% fresh air inside the interior room) and the rooms with direct openings to outdoors (complying 4% and 25 feet rules) are still only naturally ventilated, it complies with ASHRAE 62.1 - 2007 and LEED-EB 2009 consequently. Am I right or have I misinterpreted your old case with NC-2.2.?

I think your scenario could comply, since you are essentially mechanically ventilating the one interior space. In our situation the "transfer fan" was just to mix the air between the inner and outer rooms, not to supply dedicated outside air. The window openings of the outer room were greater than 4% of the combined total area of both rooms, since they were providing the outside air for both. Hope that helps.

I have a slightly different variation that I'm trying to resolve. One large room (4,000 sf metal shop) is naturally ventilated by two large garage doors (totaling 336 sf). Per your transfer fan example, can I get around the 25' requirement with ceiling fans, which are moving the fresh air around?

Jared, are those doors actually open whenever the metal shop is in use? In all weather?

Not ALL the time, but occupancy often correlates to activity going in and out of the doors. It's admittedly a low-tech solution, but one that seems to work for their situation. It seems plenty ventilated overall, but the back corner in winter is clearly the worst-case scenario. Any work-arounds you can think of?