[Equest-users] Fwd: Re: [Bldg-sim] usgbc response to outdoor air question

[Carol Gardner]

-------- Original Message --------
Subject: 	Re: [Bldg-sim] usgbc response to outdoor air question
Date: 	Mon, 17 Oct 2011 11:08:03 -0700
From: 	Carol Gardner <gems at spiritone.com>
To: 	Patrick J. O'Leary, Jr. <poleary1969 at gmail.com>
CC: 	bldg-sim at lists.onebuilding.org



Chances are they don't have a "straight answer" to give you. I would 
recommend modeling it the way that feels right to you, using your 
knowledge of how the building works and your expertise as a modeler, and 
providing documentation for the choices you made and why you believe 
they are correct. If your arguments hold together you might not have any 
trouble at all.

Carol

On 10/17/2011 10:37 AM, Patrick J. O'Leary, Jr. wrote:
> you're welcome james.  now if i could only get a straight answer on 
> how to address baseline system sizing/outdoor air rates when the 
> proposed building is evaporatively cooled with 100% outdoor air .... 
> sizing a baseline building system of packaged dx just doesn't sit 
> right when the proposed is providing 20,000 cfm with 100% outdoor 
> air.  and i get mixed comments from reviewers about too much energy 
> savings ... or providing too much outdoor air in the baseline ...
>
> On 10/17/11 9:31 AM, Jim Dirkes wrote:
>>
>> Dear Patrick,
>>
>> Thank you for sharing this GBCI response!  It is very informative 
>> and, while I won't admit that I've been modeling anything 
>> incorrectly, I _am_ going to change a couple of things J.
>>
>> In particular, I have heard on several occasions that the Increased 
>> Ventilation credit was a clear case of "IEQ vs. energy"; you make a 
>> decision to trade one against the other.  After reading the GBCI 
>> response below and then double-checking with ASHRAE 90.1, I find that 
>> they are consistent with each other and effectively allow no penalty 
>> for the increased energy caused by increased ventilation.  Very 
>> curious, considering there is no science which demonstrates a health 
>> benefit for outdoor airflows greater than that required by ASHRAE 62.1!
>>
>> The other item is that I failed to notice (and still can't find) 
>> anything in 621.1 which says that unoccupied ventilation should be 
>> zero.  I guess that is OK, but is also curious, since a portion of 
>> the ventilation calcs in 62.1 include consideration for off-gassing 
>> materials (which are always present.)
>>
>> All in all, I'm smarter than I was as a result of your post, so it's 
>> a good day!  Thanks again.
>>
>> *The Building Performance Team
>> **James V. Dirkes II, P.E., BEMP , LEED AP
>> *1631 Acacia Drive NW
>> Grand Rapids, MI 49504
>> 616 450 8653
>>
>> *From:*bldg-sim-bounces at lists.onebuilding.org 
>> [mailto:bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of 
>> *Patrick J. O'Leary, Jr.
>> *Sent:* Monday, October 17, 2011 11:46 AM
>> *To:* equest-users at lists.onebuilding.org; bldg-sim at lists.onebuilding.org
>> *Subject:* [Bldg-sim] usgbc response to outdoor air question
>>
>> back in september there was a thread about what the outdoor air rate 
>> in a baseline simulation should be compared to a proposed simulation, 
>> specifically when one is adding 30% more outdoor air to meet the 
>> ieqc2 requirement and earn 1 leed point.  there were differences of 
>> opinions about the flow rates between baseline and proposed being 
>> either the same (as required in 90.1 app g) or the baseline being the 
>> calculated per 62.1 and the proposed being as designed.
>>
>> so i submitted a support request to the usgbc and the reply i 
>> received is below, but in short the response is that unless you're 
>> using dcv optionally the outdoor air rates in the baseline and 
>> proposed energy simulations for eac1 should be the same.  the 
>> response below gives the standard responses to differing outdoor air 
>> rate scenarios.
>>
>> regards,
>> patrick
>>
>> [Fwd: Case 00531150: General LEED Questions
>>
>> -------- Original Message --------
>>
>> *Subject: *
>>
>> 	
>>
>> Case 00531150: General LEED Questions [ ref:00D49UeD.5004GN692:ref ]
>>
>> *Date: *
>>
>> 	
>>
>> Mon, 17 Oct 2011 06:54:51 +0000 (GMT)
>>
>> *From: *
>>
>> 	
>>
>> "No reply GBCI" <no-reply at gbci.org> <mailto:no-reply at gbci.org> 
>> <no-reply at gbci.org> <mailto:no-reply at gbci.org>
>>
>> *To: *
>>
>> 	
>>
>> patrick@
>>
>> Dear Patrick,
>>
>> Thank you for contacting the Green Building Certification Institute.
>>
>> You ask very good questions related to the relationship between 
>> ASHRAE Standards 62.1 and 90.1, and how these standards are applied 
>> across multiple LEED Rating System prerequisites and credits.
>>
>> The simple answer to your question is that, for systems without 
>> demand controlled ventilation, the outdoor air included in EA Credit 
>> 1 energy simulations must be the same in the Baseline and Proposed 
>> cases. If the project is attempting IEQ Credit 2 Increased 
>> Ventilation, then the values calculated in IEQc2 must be used in the 
>> EAc1 Basline and Proposed case energy models. Note that IEQc2 does 
>> not limit the project to providing only 30% more outdoor air than 
>> AHRAE 62.1 Ventilation Rate Procedure minimums, so higher amounts are 
>> acceptable, as long as they are modeled identically in both the 
>> Baseline and Proposed case energy models.
>>
>> The following generic LEED Review Comment applies to ventilation 
>> systems that do not have demand controlled ventilation:
>>
>> It is unclear whether the minimum outside air rates (in CFM) were 
>> modeled identically in the Baseline and Proposed case for all zones 
>> not having Demand Control Ventilation in the Proposed case. Please 
>> confirm that minimum outside airflow (in units of cfm) was modeled 
>> identically in the Baseline and Proposed cases using the proposed 
>> case rates. Additionally, please 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 should be modeled identically in the Baseline and Proposed case).
>>
>> The situation becomes a bit more complicated in you have systems that 
>> have demand controlled ventilation (often implemented as Carbon 
>> Dioxide control of outdoor air or as programmed control of outdoor 
>> air based on occupancy sensors.) In this case the Baseline case 
>> energy model must include the minimum outdoor air as determined by 
>> the ASHRAE 62.1 Ventilation Rate Procedure calculations for all 
>> systems having demand controlled ventilation.
>>
>> The following generic LEED Review Comment applies to ventilation 
>> systems that do have demand controlled ventilation:
>>
>> Demand control ventilation was modeled for credit in the proposed 
>> case. Appendix G allows schedule changes for demand control 
>> ventilation as approved by the rating authority (Table 
>> G3.1#4(Baseline)). As the LEED Certification rating authority, GBCI 
>> requires that the outside air ventilation rates for the Baseline case 
>> be modeled using minimum ASHRAE 62.1-2004 (or 2007 for LEED-NC 2009 
>> projects) rates wherever credit is taken for demand control 
>> ventilation in the Proposed case. The proposed case minimum rates at 
>> design conditions should be modeled as designed. Please verify that 
>> the Baseline Case model reflects ASHRAE 62.1-2004 (or 2007) minimum 
>> rates for any spaces where credit is taken for demand control 
>> ventilation, or revise the model accordingly. For all other spaces, 
>> please confirm that minimum outside airflow (in units of cfm) was 
>> modeled identically in the Baseline and Proposed cases. Additionally, 
>> please verify that all systems in both the baseline and proposed 
>> cases 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 should be 
>> modeled identically in the Baseline and Proposed case).
>>
>> Finally, even though you don't address energy recovery in your 
>> question, whether or not you have energy recovery in your ventilation 
>> systems may affect how much better (or worse) your Proposed case 
>> energy models perform in relation to your Baseline case energy models.
>>
>> The following generic LEED Review Comment addresses energy recovery 
>> in EAc1 energy models as it relates to ventilation systems.
>>
>> Energy recovery is modeled for credit in the Proposed case. Please 
>> provide further information regarding the energy recovery efficiency, 
>> verify that outside air is modeled with zero flow in both the 
>> Baseline and Proposed cases during unoccupied periods 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 
>> should be modeled identically in the Baseline and Proposed Case), and 
>> indicate the bypass mechanism used to bypass the energy recovery 
>> during mild conditions.
>>
>> I hope that helps, but if you have any further questions or concerns, 
>> please feel free to use the contact form at 
>> http://www.gbci.org/contactus and select "Follow up to GBCI 
>> Response," inputting your case number from this email's subject line.
>>
>> Best Regards,
>>
>> Dan Katzenberger, P.E., CEM, BEMP, LEED-AP BD+C
>>
>> Green Building Certification Institute
>> 2101 L Street NW, Suite 500
>> Washington, DC 20037
>> 800-795-1746 (phone)
>> 202 828-5110 (fax)
>> www.gbci.org/contactus <http://www.gbci.org/contactus>
>>
>> The text above represents a staff opinion of a particular issue, and 
>> does NOT set any precedent to be upheld during a LEED Certification 
>> Review. For official rulings in advance of a LEED Certification 
>> Review, customers should utilize the Formal Inquiries process 
>> available in LEED Online that results in a Project Credit 
>> Interpretation Ruling (Project CIR) and possibly a LEED 
>> Interpretation (formerly CIRs or Public Rulings). Applications for 
>> LEED Certification will be thoroughly reviewed based on USGBC Member 
>> balloted and approved LEED Rating Systems, with addenda, and USGBC 
>> approved LEED Interpretations, or Project CIRs administered by GBCI, 
>> as applicable. Please note that certain inquiries submitted to USGBC 
>> are forwarded to GBCI for reply as appropriate.
>>
>>
>> _______________________________
>> CUSTOMER EMAIL ADDRESS:
>> patirck@
>>
>> CUSTOMER INQUIRY:
>> I am trying to verify what the minimum outdoor airflow rate required 
>> for EAc1 is and am not sure if this requires a CIR.
>>
>> If the Proposed outdoor air ventilation is a minimum of 30% higher 
>> than the minimum required by ASHRAE 62 in order to achieve 1 LEED 
>> point for credit IEQC2 is the Baseline outdoor air rate also 30% 
>> higher than the minimum required by ASHRAE 62? or would the Baseline 
>> outdoor air ventilation rate be the minimum outdoor air rate per 
>> ASHRAE 62 calculations.
>>
>> In other words, if ASHRAE 62 requires a minimum of 1,000 CFM of 
>> outdoor air, and 1,300 CFM is provided to attain 1 LEED point via 
>> IEQC1, is the Baseline outdoor air flow rate 1,000 CFM or 1,300 CFM 
>> in the energy simulation?
>>
>> 90.1-2007/2004 both say the minimu    m outdoor airflow rates shall 
>> be the same for both the proposed and baseline building designs, as 
>> does the user manual.
>>
>> But this logic seems to reward the Proposed simulation by 
>> conditioning the additional outdoor air supplied (300 cfm in the 
>> example above) to achieve IEQC1 in the Baseline system as well as the 
>> proposed.
>>
>> The logic of using the minimum required in the Baseline case is 
>> reflected in EAC1 in the equipment efficiency requirements. Baseline 
>> efficiencies are the minimum required, e.g. SEER 13 for packaged units.
>>
>> It is the intent of the requirement that I am not sure is clear. 
>> Increasing the outdoor air ventilation rate increases the energy used 
>> to condition the outdoor air, so if the intent is to put the onus on 
>> Proposed design to show energy reduction/LEED compliance over the 
>> 90.1/62 requirements shouldn't the Baseline outdoor air be the 
>> minimum air flow rate per the ASHRAE 62 calculations? This puts the 
>> onus on the design team to provide a design that compensates for the 
>> increase in energy to meet IEQC2 by providing some method of 
>> processing the increase in outdoor air while still reducing energy 
>> consumption.
>>
>>
>>
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