Re: [EnergyPlus_Support] Purchased Air latent load

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

The purchased air model is very simple.  Using the specified supply air 
temperature, it determines the flow rate required to meet the current zone 
load.  It takes air from the zone, adds outside air if specified (use this with 
caution), and then provides the calculated flow rate of air at the specified 
supply temperature and humidity.  To determine the total load, the change in 
enthalpy is used.  To determing the sensible load, the change in temperature is 
used.  If the change in humidity is in the opposite direction of the change in 
temperature, then you will see the condition where sensible is greater than 
total.  Purchased air is an excellent model for calculating sensible loads.  
The latent loads calculated by purchased air are very approximate and are 
somewhat arbitrary given that the supply air humidity ratio is specified 
directly rather than computed as part of a system model.

Mike


On 8 May 2006 at 11:02, Petra Vaquero wrote:

> Hi!
> 
> I am using a purchased air in a building and when, in the outputs, I get 
> the sensible load and the total load I realize that, in some zones, the 
> sensible is higher than the total load. What does this means? I have a 
> negative latent load? 
> 
> Thanks
> Petra
> 
> 
> 
> 
> 
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> 


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





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