Re: [EnergyPlus_Support] Effects of Cooling Setpoint Change

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

The system has a fixed cooling supply air temperature setpoint.  For the 
constant volume case, the system is always cooling the same flow rate of air to 
the same supply temperature, no matter what the zone setpoints are.  So, the 
result of little change is chiller load is to be expected.  If there are no 
reheat coils (as the uploaded files show) then the zone temperatures will not 
be controlled at all.  It is not clear what you are expecting the constant 
volume system to do.

Mike


On 14 Dec 2007 at 21:10, eric.mcmaster wrote:

> Hello,
> 
> I have been attempting to model the effects of changing the cooling
> set point of a given building, and up to now I have been getting some
> unusual results.  The building is a Constant air volume system
> (Turndown Ratio = 1.0) which has been defined using the COMPACT:HVAC
> objects.  To model the cooling set point I altered the values within
> the the cooling set point compact schedules.   
> When the change is implemented only 2 aspects of the energy
> consumption are affected.  First the chiller load (Monthly) is very
> slightly reduced, and second the Pump load experiences a drastic
> increase in consumption ~15%.   What could be the possible reasons for
> this increase in the pump load?
> 
> Also, I have noticed that when a turndown ratio is incorporated into
> the model, the consumption of the fans within the building are reduced
> and the chiller consumption also experiences a greater reduction.
> which leads be to belive that there may be an error in the way i am
> modelling my building.
> 
> I will attempt to upload two .idf files for review.
> 
> Thank you in advance for any advice you may have.
> 
> Eric
> 
> 
> 
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
> 
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
> 
> Attachments are not allowed -- please post any files to the appropriate folder
> in the Files area of the Support Web Site.
> 
> EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the
> Documentation link and press the "search" button.
> 
> Yahoo! Groups Links
> 
> 
> 
> 
> 


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





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