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NC-2009 EAp2:Minimum Energy Performance

Minimum fresh air rates - Baseline vs. Proposed (90.1-2010)

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Green Lab
LEEDuser Basic Member
6 thumbs up

Hello,

I am currently modeling a building which is aiming to achieve EQ credit for increased ventilation. I know that this is a topic already discussed here in the forum, but it was not clear to me:

How should I model baseline minimum fresh air rates? As in proposed (62.1-2010 + 30%) or the minimum as stated by 62.1? 

After reading G3.1.2.6 exception c, it seems that the proposed is 62.1+30% and the baseline with the minimum required by code. But this means that by achieving the increased ventilation credit, proposed model is penalized by having 30% more OA... I am following ASHRAE 90.1-2010. 

Moreover, in my proposed model the zone air distribution effectiveness (Ez) is 0.8. Should I consider the same ventilation effectiveness in the baseline model? 

Thank you in advance for your time. 

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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Tue, 10/30/2018 - 19:10

So you are using the 2010 versions of 62.1 and 90.1 for a v3 project? The rules change quite dramatically between 2007 and 2010 when it comes to the outdoor air modeling requirements. The ventilation effectiveness should be the same in the baseline.
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Green Lab
LEEDuser Basic Member
6 thumbs up

Wed, 10/31/2018 - 10:08

Thank you for the response Marcus.  No, I am using the 2010 versions for a v4 project. In this case I should model the proposed according to 62.1+30%, and the baseline with the minimum OA rates from 62.1, correct? This is my understanding of G3.1.2.6 exception c: "If the minimum outdoor air intake flow in the proposed design is provided in excess of the amount required by the rating authority or building official, then the baseline building design shall be modeled to reflect the greater of that required by the rating authority or building official and will be less than the proposed design.” Does this exception applies even when we are attempting EQ credit Enhanced IAQ strategies – increased ventilation? I ask this because by having different OA intake flows in proposed/baseline (according to exception c) in order to attempt the increased ventilation credit, the proposed design is being penalized at the whole-building energy simulation level for a having a positive feature (increased ventilation).   I found different replies on modeling related forums regarding this topic, probably because as you said, it changed from 2007 to 2010.  Thank you.
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Fri, 11/02/2018 - 14:13

You are posting in a LEED 2009 forum. Please post your questions in the appropriate v4 forum. The point of a public forum is not just to help one person with an answer but to help many. If the questions are not in the right forum they are not helpful to others.
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Green Lab
LEEDuser Basic Member
6 thumbs up

Mon, 11/05/2018 - 09:53

I am sorry Marcus. I must unintentionally have selected the 2009 section. I will move this post to the v4 forum. 

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