Re: [EnergyPlus_Support] outside air problem

["Michael J. Witte" <mjwitte@xxxxxxxx>]

1.  Both methods will introduce the same quantity of outdoor air into the 
system.  Not all fan coil system rely on a separate system to introduce outdoor 
air, some are built with an outside air intake.  Is there a big difference 
between simulating it as a separate system or as part of the fan coil unit?  
That depends on whether the separate system would do any special control for 
humidity.  If not, the difference in results will be small.  So use the 
simplest method unless there is a significant reason to use a more complex 
model.

2.  These values have a very small impact on coil sizing.  The default values 
can be used for most applications.

2b.  Consideration of humidity control is very regional.  You should model what 
is important for your climate.

Mike


On 14 Nov 2005, at 9:39, eric_zhou1223 wrote:

> Hi,
> 
> 1.For the Dxcoil and Fancoil system, users may define required fresh 
> air for a zone using the outdoor air mixer. The autosized value in 
> the field ¡°maximum outside air flow rate¡± could satisfy the 
> ventilation requirement of occupants. My question is , as we know, 
> since there exists in reality another air loop specially for the 
> fresh air inducement, is this method here only a simulative method 
> to handle the ventilation problem? Can I use this simplified way here
> (defining the desired fresh air amount in above field ) to simulate 
> a ¡° Fancoil + outdoor air¡± system, instead of using a complex  
> Fancoil system along with an additional Fresh Air Handling Unit to 
> meet the ventilation demand?  What is the difference between the two 
> method from a fresh air supply perspective?
> 
> 2  How can I identify the fields ¡°Zone cooling/heating design 
> supply air humidity ratio¡±?  The default values can be regarded as  
> ¡°standard ¡± values or need to be revised based on each situation ? 
> I thought the value , specially for the heating , seem to be over 
> dry.
> 
> Is ignoring the humidity control a common practice for an office 
> building energy simulation? 
> 
> Thank you very much
> 
> Eric
> 
> 
> 
> 
> 
> 
> 
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> 
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> 
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> 
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> 
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> 
> 
> 
> 
> 
> 
> 
> 



========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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