[Bldg-sim] usgbc response to outdoor air question

[Martin Roy ing. LEED AP]

Ouch!
In the Model energy code in Canada only up to 20% 
more than ASHRAE 62 is allowed in the base 
case.  Imagine a building with 100% more OA and a 
ERV of 70% on the proposed case it can easily 
reach 10 EAcr1 point especially in cold climate.

Martin


At 21:41 15/11/2011, Reba Schaber wrote:
>Content-Language: en-US
>Content-Type: multipart/alternative;
> 
>boundary="_000_FAA9B7F58E5E4A46BDDF900F4CCAC3FE03ABA763DD3DPHSERVERphm_"
>
>RE:  “. . . can’t find) anything in 621.1 which 
>says that unoccupied ventilation should be zero.”
>
>I think this requirement comes from the mandatory provisions of 90.1.
>
>6.4.3.4.3 Shutoff Damper Controls. Both outdoor
>air supply and exhaust systems shall be equipped with motorized
>dampers that will automatically shut when the systems or
>spaces served are not in use. Ventilation outdoor air dampers
>shall be capable of automatically shutting off during preoccupancy
>building warm-up, cool down, and setback, except
>when ventilation reduces energy costs (e.g., night purge) or
>when ventilation must be supplied to meet code requirements.
>
>Thoughts??
>
>Reba
>
>From: bldg-sim-bounces at lists.onebuilding.org 
>[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Jim Dirkes
>Sent: Monday, October 17, 2011 9:32 AM
>To: equest-users at lists.onebuilding.org; 'bldg-sim at lists.onebuilding.org'
>Subject: Re: [Bldg-sim] usgbc response to outdoor air question
>
>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: 
><mailto:bldg-sim-bounces at lists.onebuilding.org>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: 
><mailto:equest-users at lists.onebuilding.org>equest-users at lists.onebuilding.org; 
><mailto:bldg-sim 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" 
><mailto:no-reply at gbci.org><no-reply at gbci.org> 
><mailto:no-reply at gbci.org><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>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)
><http://www.gbci.org/contactus>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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----------

Martin Roy, ing. PA LEED®, président
Martin Roy et associés
1805 chemin Oka,
Deux-Montagnes, Qc
J7R 1N3


Tel: 450-623-0340
Cell. 514-594-6352

www.mra.qc.ca






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