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Re: [EnergyPlus_Support] Re: Minimum OA Calculation/Sum



The OA flow rate set using the zone sizing object will be fixed for both 
min and max and can not be used to model DCV. You should run a test file 
to model what you intend to do with and without a Vent:Mech object. You 
could performing a test with an existing example file. Use 
5ZoneVAV-Pri-SecLoop  Run the simulation and view the OA mass flow rate 
in the csv. You will have to add a report variable to see the mass flow 
rate at the outside air node (VAV Sys 1 Outside Air Inlet, System Node 
MassFlowRate). Add the Vent:Mech object and repeat the test (don't 
forget to add the name of the Vent:Mech object in the Controller:Outside 
Air object). You can repeat this test by changing the zone sizing 
objects in several ways.

Alan Jackson wrote:
>
> Richard
>
> Thank you for your help. There is one thing I am still unclear about
> from your response. Are you saying that the OA set in the Zone Sizing
> object will not adjust to zone occupancy? If so, wouldn't the Zone
> Sizing also handle DCV?
>
> Thanks
>
> -
> aj
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> <RRaustad@...> wrote:
> >
> > Your are correct in that the zone sizing object determines the minimum
> > OA flow rate when autosizing. The ventilation mechanical object is used
> > to provide demand controlled ventilation. Also notice that the flow
> > rates specified in the Vent:Mech object can not be autosized. So the
> > Vent:Mech works in conjunction with the OA system and the OA air flow
> > rates are restricted to the min/max flow rates in the OA controller..
> >
> > Alan Jackson wrote:
> > >
> > > Can someone explain or point me towards the documentation has better
> > > clarification on the way outdoor air is calculated? There are many
> > > fields within the IDF file that autosize the minimum OA and I am
> > > curious as to where these values are coming from. I initially thought
> > > that they were coming from the Zone Sizing information but then I came
> > > across the VENTILATION:MECHANICAL controller and could not distinguish
> > > between the difference in functionality at that point. I have read the
> > > I/O document and would appreciate a better understanding of how this
> > > all works outside of economizer mode.
> > >
> > > thanks
> > >
> > > -
> > > aj
> > >
> > >
> >
> > --
> > Richard A. Raustad
> > Senior Research Engineer
> > Florida Solar Energy Center
> > University of Central Florida
> > 1679 Clearlake Road
> > Cocoa, FL 32922-5703
> > Phone: (321) 638-1454
> > Fax: (321) 638-1439 or 1010
> > Visit our web site at: http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> >
> > UCF - From Promise to Prominence: Celebrating 40 Years
> >
>
>  

-- 
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
1679 Clearlake Road
Cocoa, FL  32922-5703
Phone:   (321) 638-1454
Fax:     (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu

UCF - From Promise to Prominence: Celebrating 40 Years


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