[Equest-users] GBCI comments on DCV (Carol Gardner)

[Paul Riemer]

Thank you Bill.

Allow me to clarify "prone to COLLISIONS" and that to note the Appendix A of the 62.1-2007 User's Manual throws up its hands on page A-7 stating that "DCV for multiple zone recirculating systems has not been adequately developed at this time."  Appendix A still provides guidance for constant volume single zone systems with or without flow measuring stations.

Paul Riemer
Dunham


From: William Bahnfleth [mailto:WBahnfleth at engr.psu.edu]
Sent: Tuesday, July 27, 2010 11:20 AM
To: Cam Fitzgerald; Paul Riemer; Karen Walkerman; James Hansen
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] GBCI comments on DCV (Carol Gardner)


That UM section was withdrawn because it involved so many unsubstantiated assumptions.  ASHRAE just awarded a research contract to deal with this issue at it's annual meeting in June.



Bill Bahnfleth



Cam Fitzgerald <cam at energyopportunities.com> wrote:


Paul, et al:

Without going into great detail, I take exception to the statement that "62.1 and its user's manual throw up their hands on DCV in multi-zone systems."  It seems to me that the 62.1-2004 User's Manual is quite specific about how the minimum ventilation rates should be determined when a multi-zone systems serves spaces with and without DCV starting on page A-5.  You may want to review this guidance.

Cam Fitzgerald

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Paul Riemer
Sent: Tuesday, July 27, 2010 11:42 AM
To: 'Karen Walkerman'; James Hansen
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] GBCI comments on DCV (Carol Gardner)

I nodded somewhat along with Karen's email but we probably need to sharpen the saber in addition to rattling it.

Demand Controlled Ventilation (DCV) is a control approach.  Std 62.1 is a largely about quantitative ventilation thresholds.  Std 90.1 requires DCV in some instances but control approach,  It does not reference specific maximum or minimum, design or operating ventilation thresholds. So a 90.1 compliant design can use DCV to modulate between thresholds set by professional judgment, local code, exhaust/pressurization concerns, or even an owner requirement such as 30% above Std 62.1.

It really is a complex intersection of LEED, Std 62.1 and Std 90.1 and prone to collusions. Even Standard 62.1 and its users manual essentially throw up their hands on DCV in multi-zone systems.

Consider a project that is required to implement DCV in some space, and it does so but not to the GBCI's interpretation of Std 62.1 values. Do the differences count for and/or against its EAp2 compliance and/or its EAc1 points?  What if the project is IEQc2 Increased Ventilation? What if the project is also implementing DCV in spaces not required to have it?  Does it matter if it is based on sensing CO2, sensing occupancy, or time of day?  What if they proposed and baseline mechanical systems are multi-zone, single zone, or one of each?  ...

This is so complex, I can see why they are reacting project by project.  I would take the review Thomas shared as one point in the discussion, not universal guidance for all projects.  They cannot possibly be smart enough to write guidance for all cases without sacrificing something currently held sacred by someone.

With every model and especially every exceptional calculation the modeler should build reasonable models and be prepared to justify them as reasonable.  With DCV the justification probably needs to be in the initial submittal.

Paul Riemer
Dunham

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Karen Walkerman
Sent: Tuesday, July 27, 2010 8:33 AM
To: James Hansen
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] GBCI comments on DCV (Carol Gardner)

You are missing the fact that the rules are being changed at the REVIEW stage.  This requires the energy modeler to do a-lot of extra work to change the baseline model during the review stage.  It also means that after changing the model, if the reviewer has any additional comments or questions, the energy modeler will have to go through an additional review, and pay an additional fee to have the USGBC look at their documentation again.

Also, the fact that this rule seems to be implemented for some projects, and not for others means that buildings are not being rated fairly against each other.

The debate about whether this makes sense or not should be kept separate from this discussion.  My main concern is that rules are being changed without letting the players know.  Any time they make changes, it needs to be documented publicly, preferably with changes only applying to projects registered after the date of publication.

We can debate separately whether this rule change makes sense.  Yes, I understand that some "gaming" of the system could happen, in theorgy, but in many cases, adding HUGE amounts of outdoor ventilation air as you suggest is far too costly to implement.

Thanks,

--
Karen Walkerman

On Tue, Jul 27, 2010 at 9:13 AM, James Hansen <JHANSEN at ghtltd.com<mailto:JHANSEN at ghtltd.com>> wrote:
I'm not sure I really understand what the fuss is about.  If you're designing and modeling a building that does NOT have DCV, then it seems entirely fair (and accurate) to model the same ventilation rates in both the baseline and the proposed.  If, however, you are implementing a DCV strategy, then regardless of what you set your "maximum" OA rate at for the proposed model, in reality, the DCV system is going to keep OA flow rates near or below the ASHRAE 62.1 requirements (in real life operation).

If the TAG committee didn't require you to model the baseline building at ASHRAE 62.1 flow rates when DCV is being implemented, then theoretically you could input an astronomically high OA flow rate for both models, knowing that your proposed model would NEVER run at such a condition and would have an unfair advantage.

This seems like an entirely acceptable and fair ruling.  What am I missing?

GHT Limited
James Hansen, PE, LEED AP
Senior Associate
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703-243-1200 (Office)
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From: equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org> [mailto:equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org>] On Behalf Of Karen Walkerman
Sent: Tuesday, July 27, 2010 9:05 AM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>

Subject: Re: [Equest-users] GBCI comments on DCV (Carol Gardner)

Is anyone on this list-serve on the EA Credit 1 committee, or know someone who is?  If the the GBCI or USGBC has changed the modeling requirements and is only letting modelers know during the documentation review stage, I find this very disturbing for a number of reasons.  It would be great if we can get some straight answers on this from someone at one of these organizations who actually knows what is going on.

I am happy to draft an email outlining concerns, but I don't know who to send it to.  If anyone does, or would like to help me with this, please feel free to contact me directly.

Thanks,

--
Karen Walkerman

On Tue, Jul 27, 2010 at 8:28 AM, Peter Worley <peter.worley at arup.com<mailto:peter.worley at arup.com>> wrote:

Sorry for what may seem like a dumb question...



Why, if you're designing to ASHRAE 62.1, would you increase the outside air quantity beyond the minimums (unless required for lab exhaust, etc)?



I have a project where the local code (referencing IMC 2003) requires a higher level of minimum ventilation than ASHRAE 62.1. I've therefore designed to this amount and modeled it in both my proposed and baseline cases. I can't imagine that this will be problematic. Do you disagree?



Thanks,

Pete


Peter Worley
Mechanical Engineer

155 Avenue of the Americas  New York  NY  10013  USA
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f +1 212 229 1056
www.arup.com<http://www.arup.com>

[cid:image001.gif at 01CB2D7E.62B37B50]

From: Tom Serra [mailto:tserra at emoenergy.com<mailto:tserra at emoenergy.com>]
Sent: Monday, July 26, 2010 12:14 PM

To: Karen Walkerman
Cc: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: Re: [Equest-users] GBCI comments on DCV (Carol Gardner)

No documentation exists supporting the new method.  GBCI is pulling the "rating authority" card and implementing their own requirements.   I tried to argue my case that they are going against the procedure in ASHRAE, but they did not change their requirement.  I have expressed my opinion that a document should be posted on the website that shows this new requirement but I have yet to see anything new.  Otherwise you may be expecting savings from DCV that will be rejected and then the MEP or modeler will look foolish.  They should have implemented a cut-off date for projects already in the system similar to the "District Thermal" change they made in May 2008.


In reality the DCV will still result in energy savings but the paper design savings will be lost.  I believe GBCI and USGBC are trying to prevent "gaming" of the system.  A designer could grossly oversize the ventilation system and then gain tremendous savings by implementing DCV.  This new requirement forces the designer to pursue other ventilation strategies if they want to claim savings for DCV.  Unfortunately the only way we are learning of this requirement is through clarification questions.  This lack of communication is what really upsets me.

The only solution that I see is that all spaces with demand control ventilation should be designed to ASHRAE 62.1 minimums.  Also, teams should not pursue the 30% increase ventilation credit.

Thomas Serra
Project Manager
EMO Energy Solutions, LLC
3141 Fairview Park Drive, Suite 450
Falls Church, VA 22042
voice 703-205-0445 ex-113
fax 703-205-0449
On Mon, Jul 26, 2010 at 11:22 AM, Karen Walkerman <kwalkerman at gmail.com<mailto:kwalkerman at gmail.com>> wrote:
Can anyone find documentation requiring the baseline to use ASHRAE 62.1 ventilation rates?  The table in EA Credit 1 under HVAC System Selection for the baseline design states:

"Outdoor ventilation rates should be identical to the proposed case"

There are no exceptions listed anywhere in the LEED documentation (I am currently looking at LEED 2009, but have reviewed this in the past under LEED 2.2).

We have had DCV be approved in the past with no questions.

--
Karen

On Mon, Jul 26, 2010 at 11:08 AM, Tom Serra <tserra at emoenergy.com<mailto:tserra at emoenergy.com>> wrote:
I've had many comments.  They have changed their perspective as the rating authority and are requiring outside air treatment procedures that are outside of ASHRAE 90.1 section G procedures.  Typically design outside air volume is the same between the baseline and proposed, but if you are using DCV they now require you to model the baseline with the minimum ASHRAE 62.1 volume.  So, if you have greater OA volume in your proposed model, you may be penalized depending on your DCV method and diversity schedule for occupants in the area with DCV control.

Here is an example  clarification question:

1.       CLARIFY:  Demand control ventilation was modeled for credit for RTU1 and RTU2 in the Proposed case as indicated in Table 1.4 of the Template; however, the outdoor air volume for RTU1 and RTU2 in the Baseline model was not modeled at the ASHRAE 62.1-2004 minimum rates (1,066 cfm for each RTU) as determined in EQp1: Minimum IAQ Performance. Appendix G allows schedule changes for demand control ventilation as approved by the rating authority (Table G3.1.4(Baseline)). As the rating authority, GBCI requires that the outside air ventilation rates for the Baseline Case be modeled using minimum ASHRAE 62.1-2004 rates wherever credit is taken for demand control ventilation in the Proposed Case. The Proposed case minimum rates at design conditions must be modeled as designed.


TECHNICAL ADVICE:  Revise the Baseline model so the minimum outdoor air volume is modeled at 1,066 cfm for RTU1 and RTU2 in the Baseline model. In addition, provide revised SV-A reports for RTU1 and RTU2 reflecting the changes. Further, verify that all systems in both the Baseline and Proposed case are modeled with zero outside air flow when fans are cycled on to meet unoccupied setback temperatures unless health or safety regulations mandate an alternate minimum flow during unoccupied periods (in which case, the unoccupied outside air rates must be modeled identically in the Baseline and Proposed Case).


Thomas Serra
Project Manager
EMO Energy Solutions, LLC
3141 Fairview Park Drive, Suite 450
Falls Church, VA 22042
voice 703-205-0445 ex-113
fax 703-205-0449
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