usgbc response to outdoor air question

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Ok, so I received this comment. The one with the provide ASHRAE minimums in the Baseline for spaces with DCV. I understand this is a generic comment - Ok.
However, LEED IEQ Credit 2 is not being pursued and the ASHRAE minimum ventilation requirements are what is being Proposed for in each space that has DCV.

Does this not mean that the Baseline ventilation rate and the Proposed ventilation rate will still be equal?
Not sure how to respond other than to simply say what is stated here.

Thanks,
Kevin

Kevin Kyte2's picture
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Reputation: 2

My understanding is that for a 90.1-2007 outside air is modeled at the same CFM even if it's beyond ASHRAE 62.1 requirements with no energy penalty. However, this is no longer true in 90.1-2010 where the baseline is to follow ASRAE 62.1.

Also, I thought there was a ruling or interpretation to 62.1 that only allowed the elimination of the occupant portion of the ventilation to be shut off during unoccupied hours, but the area based outside air needs to be maintained at night to handle off-gassing. I believe the 90.1 folks are still discussing how to incorporate this ruling into the standard.

If you don't have more DCV than the baseline, just use show in a calculation the total CFM and fraction of outside air for each AHU and show them the total is approximately the same. There is some latitude here for rounding errors and the like as some complex buildings may be off by a few percent. If your proposed outside cfm is slightly greater than your baseline outside cfm, then you should definitely be ok as your model will be conservative.

Hope that helps,

Fred Betz PhD., LEED AP (r)BD&C

Fred Betz's picture
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Joined: 2011-09-30
Reputation: 0

ASHRAE 62.1-2010 may be viewed online for free from the ASHRAE website at:
https://www.ashrae.org/standards-research--technology/standards--guidelines.
Its a little slow and painful to view and navigate since it is a free.

Also, all approved addenda may be downloaded in PDF from here:
https://www.ashrae.org/standards-research--technology/standards-addenda.

I reviewed both documents and did not see any rulings, interpretations or
addenda that would indicate that the area based portion of the ventilation
rate is required to operate 24/7 or during unoccupied periods. If anyone
has a better resource than this please post.
Thanks,
Dennis

Dennis Knight's picture
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Joined: 2012-11-12
Reputation: 0

My understanding is that for a 90.1-2007 outside air is modeled at the same CFM even if it's beyond ASHRAE 62.1 requirements with no energy penalty. However, this is no longer true in 90.1-2010 where the baseline is to follow ASRAE 62.1.

Also, I thought there was a ruling or interpretation to 62.1 that only allowed the elimination of the occupant portion of the ventilation to be shut off during unoccupied hours, but the area based outside air needs to be maintained at night to handle off-gassing. I believe the 90.1 folks are still discussing how to incorporate this ruling into the standard.

If you don't have more DCV than the baseline, just use show in a calculation the total CFM and fraction of outside air for each AHU and show them the total is approximately the same. There is some latitude here for rounding errors and the like as some complex buildings may be off by a few percent. If your proposed outside cfm is slightly greater than your baseline outside cfm, then you should definitely be ok as your model will be conservative.

Hope that helps,

Fred Betz PhD., LEED AP (r)BD&C

Fred Betz's picture
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Joined: 2011-09-30
Reputation: 0

Hello All,

Please see the following relevant quote from 62.1 2010:

To me this implies that all of the requirements in section 6 (which include
both the area and occupant components) are only applicable ?when [spaces]
are expected to be occupied?.

Regards,

Mike

*From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Dennis Knight
*Sent:* Thursday, September 19, 2013 5:47 PM
*To:* Fred Betz
*Cc:* Kevin Kyte; bldg-rate at lists.onebuilding.org;
equest-users at lists.onebuilding.org; bldg-sim at lists.onebuilding.org
*Subject:* Re: [Bldg-sim] usgbc response to outdoor air question

ASHRAE 62.1-2010 may be viewed online for free from the ASHRAE website at:
https://www.ashrae.org/standards-research--technology/standards--guidelines.
Its a little slow and painful to view and navigate since it is a free.

Also, all approved addenda may be downloaded in PDF from here:
https://www.ashrae.org/standards-research--technology/standards-addenda.

I reviewed both documents and did not see any rulings, interpretations or
addenda that would indicate that the area based portion of the ventilation
rate is required to operate 24/7 or during unoccupied periods. If anyone
has a better resource than this please post.

Thanks,

Dennis

Mike Karpman's picture
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Joined: 2011-09-30
Reputation: 0

Dennis,
Attached is an interpretation from ASHRAE indicating the area based ventilation rate cannot be turned off during unoccupied hours (applicable to 2007 and 2010). Subsequently, ASHRAE is in the process of issuing an addendum that does allow the area based rate to be turned off based on occupancy controls. The addendum (also attached) went out for public review last spring. I don't see that it has been published on the ASHRAE website yet, so I'm not sure whether it has been fully approved by the committee yet.

Also, in my experience, LEED (v2009) requires that the baseline ventilation rate comply with the ASHRAE 62.1 minimum when DCV controls are implemented in the proposed design for spaces not required to have it per 90.1. This would be the only scenario where baseline ventilation rates differ from the proposed (i.e. no energy penalty for over ventilating). This changes for LEED v4 which used 90.1-2010.
Regards,

Bill Talbert PE, LEED(r) BD+C

Bill Talbert's picture
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Reputation: 0

Let me go ahead and confuse things further: IEQp1 requires that:

" 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."

So if your project is in a state that has adopted 62.1-2010 (such as OH) , then that is the standard you should be referencing. Which addenda you apply is at your discretion.

90.1 is very insistent that unless a building is intended to operate 24hrs a day, the system should not be running when the building is not occupied. I take that as what is intended by the phrase "expected to be occupied". The control on individual spaces on occupancy while the whole building is in occupied mode would be a separate matter where I can understand wanting to cover the area component.

I guess I've never heard anyone push the idea that building types such as schools or libraries should be ventilated 24hrs a day so that makes me a bit skeptical of a interpretation that would lead down that path.

Brendan Hall, PE, LEED AP BD+C

Hall, Brendan's picture
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Reputation: 1

Philip: One clarification - the energy code and 62.1 don?t decide if the HVAC system needs to run to provide heating or cooling. Bill?s excerpt states that if the HVAC system is going to operate due to heating/cooling/schedule, then you have to maintain at least the area component of the ventilation air. As he mentions pertaining to the proposed addendum, it seems to make sense to many of us that if occupancy is zero then the outside air might also be zero during that time, even for the area component. Otherwise why would you be allowed to turn the unit off?

Your laboratory case might also have ventilation due to contaminants to consider which could supersede the 62.1 area component pretty easily anyway. Food storage is a different issue. First off, you might need to decide if the space is really an occupied space and does ASHRAE 62.1 apply, or if it is unoccupied storage. (Still conditioned!) Obviously the temperature/humidity requirements of the food, would determine if the HVAC system runs all of the time or not.

Brendan: Not sure about discretionary ? most building codes or similar regulations will (must?) be absolute ? requiring use of the standard as issued on a certain date, or including all addendums as of the current date. LEED is one of the few exceptions that allows the designer to choose whether to use an addendum or not, and skip over intermediate addenda. So if the local code was more stringent than LEED (even for a more recent version of the same ASHRAE standard) it might not be discretionary? I?m not sure about Ohio?s specific requirements, maybe they do allow discretion.

David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP

David Eldridge's picture
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Joined: 2012-05-08
Reputation: 1

Hello All,

Please see the following relevant quote from 62.1 2010:

To me this implies that all of the requirements in section 6 (which include
both the area and occupant components) are only applicable ?when [spaces]
are expected to be occupied?.

Regards,

Mike

*From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Dennis Knight
*Sent:* Thursday, September 19, 2013 5:47 PM
*To:* Fred Betz
*Cc:* Kevin Kyte; bldg-rate at lists.onebuilding.org;
equest-users at lists.onebuilding.org; bldg-sim at lists.onebuilding.org
*Subject:* Re: [Bldg-sim] usgbc response to outdoor air question

ASHRAE 62.1-2010 may be viewed online for free from the ASHRAE website at:
https://www.ashrae.org/standards-research--technology/standards--guidelines.
Its a little slow and painful to view and navigate since it is a free.

Also, all approved addenda may be downloaded in PDF from here:
https://www.ashrae.org/standards-research--technology/standards-addenda.

I reviewed both documents and did not see any rulings, interpretations or
addenda that would indicate that the area based portion of the ventilation
rate is required to operate 24/7 or during unoccupied periods. If anyone
has a better resource than this please post.

Thanks,

Dennis

Mike Karpman's picture
Offline
Joined: 2011-09-30
Reputation: 0

Dennis,
Attached is an interpretation from ASHRAE indicating the area based ventilation rate cannot be turned off during unoccupied hours (applicable to 2007 and 2010). Subsequently, ASHRAE is in the process of issuing an addendum that does allow the area based rate to be turned off based on occupancy controls. The addendum (also attached) went out for public review last spring. I don't see that it has been published on the ASHRAE website yet, so I'm not sure whether it has been fully approved by the committee yet.

Also, in my experience, LEED (v2009) requires that the baseline ventilation rate comply with the ASHRAE 62.1 minimum when DCV controls are implemented in the proposed design for spaces not required to have it per 90.1. This would be the only scenario where baseline ventilation rates differ from the proposed (i.e. no energy penalty for over ventilating). This changes for LEED v4 which used 90.1-2010.
Regards,

Bill Talbert PE, LEED(r) BD+C

Bill Talbert's picture
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Joined: 2011-09-30
Reputation: 0

Let me go ahead and confuse things further: IEQp1 requires that:

" 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."

So if your project is in a state that has adopted 62.1-2010 (such as OH) , then that is the standard you should be referencing. Which addenda you apply is at your discretion.

90.1 is very insistent that unless a building is intended to operate 24hrs a day, the system should not be running when the building is not occupied. I take that as what is intended by the phrase "expected to be occupied". The control on individual spaces on occupancy while the whole building is in occupied mode would be a separate matter where I can understand wanting to cover the area component.

I guess I've never heard anyone push the idea that building types such as schools or libraries should be ventilated 24hrs a day so that makes me a bit skeptical of a interpretation that would lead down that path.

Brendan Hall, PE, LEED AP BD+C

Hall, Brendan's picture
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Joined: 2011-09-30
Reputation: 1

Question, in a school or facility that contains aquariums, food goods or
anything that has a storage temperature limit less than or equal to outdoor
air temperature is there not allowance for this?

A high school science lab in phoenix for example simply cannot be left
without ventilation or cooling on a 105?F evening occupied or not.

Regards Philip

*From:* equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Hall, Brendan
*Sent:* September-20-13 1:59 PM
*To:* Bill Talbert; Mike Karpman; Dennis Knight; Fred Betz
*Cc:* equest-users at lists.onebuilding.org; bldg-sim at lists.onebuilding.org;
bldg-rate at lists.onebuilding.org
*Subject:* Re: [Equest-users] [Bldg-rate] [Bldg-sim] usgbc response to
outdoor air question

Let me go ahead and confuse things further: IEQp1 requires that:

? 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*.?

So if your project is in a state that has adopted 62.1-2010 (such as OH) ,
then that is the standard you should be referencing. Which addenda you
apply is at your discretion.

90.1 is very insistent that unless a building is intended to operate 24hrs
a day, the system should not be running when the building is not occupied.
I take that as what is intended by the phrase ?expected to be occupied?.
The control on individual spaces on occupancy while the whole building is
in occupied mode would be a separate matter where I can understand wanting
to cover the area component.

I guess I?ve never heard anyone push the idea that building types such as
schools or libraries should be ventilated 24hrs a day so that makes me a
bit skeptical of a interpretation that would lead down that path.

Brendan Hall, PE, LEED AP BD+C

*From:* equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Bill Talbert
*Sent:* Friday, September 20, 2013 12:20 PM
*To:* Mike Karpman; Dennis Knight; Fred Betz
*Cc:* equest-users at lists.onebuilding.org; bldg-sim at lists.onebuilding.org;
bldg-rate at lists.onebuilding.org
*Subject:* Re: [Equest-users] [Bldg-rate] [Bldg-sim] usgbc response to
outdoor air question

Dennis,

Attached is an interpretation from ASHRAE indicating the area based
ventilation rate cannot be turned off during unoccupied hours (applicable
to 2007 and 2010). Subsequently, ASHRAE is in the process of issuing an
addendum that does allow the area based rate to be turned off based on
occupancy controls. The addendum (also attached) went out for public review
last spring. I don?t see that it has been published on the ASHRAE website
yet, so I?m not sure whether it has been fully approved by the committee
yet.

Also, in my experience, LEED (v2009) requires that the baseline ventilation
rate comply with the ASHRAE 62.1 minimum when DCV controls are implemented
in the proposed design for spaces not required to have it per 90.1. This
would be the only scenario where baseline ventilation rates differ from the
proposed (i.e. no energy penalty for over ventilating). This changes for
LEED v4 which used 90.1-2010.
Regards,

*Bill Talbert** *PE, LEED? BD+C

*From:* bldg-rate-bounces at lists.onebuilding.org [
mailto:bldg-rate-bounces at lists.onebuilding.org]
*On Behalf Of *Mike Karpman
*Sent:* Friday, September 20, 2013 11:00 AM
*To:* Dennis Knight; Fred Betz
*Cc:* equest-users at lists.onebuilding.org; bldg-sim at lists.onebuilding.org;
bldg-rate at lists.onebuilding.org
*Subject:* Re: [Bldg-rate] [Bldg-sim] usgbc response to outdoor air question

Hello All,

Please see the following relevant quote from 62.1 2010:

To me this implies that all of the requirements in section 6 (which include
both the area and occupant components) are only applicable ?when [spaces]
are expected to be occupied?.

Regards,

Mike

*From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Dennis Knight
*Sent:* Thursday, September 19, 2013 5:47 PM
*To:* Fred Betz
*Cc:* Kevin Kyte; bldg-rate at lists.onebuilding.org;
equest-users at lists.onebuilding.org; bldg-sim at lists.onebuilding.org
*Subject:* Re: [Bldg-sim] usgbc response to outdoor air question

ASHRAE 62.1-2010 may be viewed online for free from the ASHRAE website at:
https://www.ashrae.org/standards-research--technology/standards--guidelines.
Its a little slow and painful to view and navigate since it is a free.

Also, all approved addenda may be downloaded in PDF from here:
https://www.ashrae.org/standards-research--technology/standards-addenda.

I reviewed both documents and did not see any rulings, interpretations or
addenda that would indicate that the area based portion of the ventilation
rate is required to operate 24/7 or during unoccupied periods. If anyone
has a better resource than this please post.

Thanks,

Dennis

Philip Kennedy's picture
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Joined: 2013-08-09
Reputation: 0

One needs to specify a setup and setback temperature for unoccupied periods. The HVAC systems are allowed to cycle on and off to keep the areas within reasonable ranges. There also needs to be a control routine that determines when the HVAC systems need to be started to reach the occupied setpoint by the schedule time (optimum start). This is how I model the buildings and how I have programmed them to operate as part of ESCO projects.

One can?t do this in critical spaces such as labs or hospitals. In those cases you can use a reduce airflow when unoccupied but you cannot turn off the fans. One sets up occupied and unoccupied minimum airflow schedules to reflect this.

The discrepancy pointed out in this e-mail trail is not the only time that ASHRAE 62.1 and 90.1 contradict each other.

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Richard-Ellison's picture
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Philip: One clarification - the energy code and 62.1 don?t decide if the HVAC system needs to run to provide heating or cooling. Bill?s excerpt states that if the HVAC system is going to operate due to heating/cooling/schedule, then you have to maintain at least the area component of the ventilation air. As he mentions pertaining to the proposed addendum, it seems to make sense to many of us that if occupancy is zero then the outside air might also be zero during that time, even for the area component. Otherwise why would you be allowed to turn the unit off?

Your laboratory case might also have ventilation due to contaminants to consider which could supersede the 62.1 area component pretty easily anyway. Food storage is a different issue. First off, you might need to decide if the space is really an occupied space and does ASHRAE 62.1 apply, or if it is unoccupied storage. (Still conditioned!) Obviously the temperature/humidity requirements of the food, would determine if the HVAC system runs all of the time or not.

Brendan: Not sure about discretionary ? most building codes or similar regulations will (must?) be absolute ? requiring use of the standard as issued on a certain date, or including all addendums as of the current date. LEED is one of the few exceptions that allows the designer to choose whether to use an addendum or not, and skip over intermediate addenda. So if the local code was more stringent than LEED (even for a more recent version of the same ASHRAE standard) it might not be discretionary? I?m not sure about Ohio?s specific requirements, maybe they do allow discretion.

David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP

David Eldridge's picture
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Reputation: 1