OVER/UNDER SIZING

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Hi, 

I am doing Energy Simulation and i came across Over/Under sizing problem, Which leads to baseline energy consumption go very high. And i cannot remove the heating and cooling supply air dry bulb because of G3.1.2.8. (Design airflow rate)

From Trane Trace Help i can read that, 

"Over/undersizing, which appears on the Checksums and Airflow Loads reports, typically occurs with constant volume system types, especially Single Zone (SZ), Fan Coil (FC), Variable Temperature Constant Volume (VTCV), and Multizone (MZ) systems"

And my baseline system is Variable Volume reheat (30% Min Flow Default) (which is not mention on the list of trane trace)  but still showing over/under sizing. 

Is there any way i can get rid of this problem?

I appreciate your comments. 

Thank you 

Anil Bhari

anilbhari1's picture
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Joined: 2011-11-14
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It isn't too difficult to get over/undersizing for a VAV system.

Typically, this results if you set the airflow for the system and the Supply air temperature. (remember that per G3.1.2.8, you do not have to set the heating supply air dry bulb. The heating supply air should actually be left blank for the baseline!)

In most baseline systems, you should leave the airflow set to "to be calculated". However, there are many exceptions, and sometimes, you just end up with over/undersizing and that is within the rules of LEED.

Bob F's picture
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Joined: 2010-06-30
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Thanks bob

anilbhari1's picture
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Joined: 2011-11-14
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