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Re: [EnergyPlus_Support] Re: Modeling Degradation of a VAV System Using EnergyPlus
I can't help you with numbers, but once you have determined what performance
characteristics to change and by how much, I can help with the mechanics of
implementing it in EnergyPlus.
In EnergyPlus, equipment performance parameters cannot be input as a function
of time. However, it would seem that degradation would take place on the order
of years rather than days. So one approach would be to do an annual simulation
with "like-new" performance, change the performance as desired, then do another
annual simulation, and so on.
The changes can be automated using the EnergyPlus macro language (see the
Auxiliary Programs document), and batch runs can be done using the Group tab in
EP-Launch or by writing your own DOS batch files which call RunEPlus.bat.
Mike
On 14 Sep 2006 at 17:58, Philip Haves wrote:
> Noel,
>
> Can you be more specific about what you mean by:
> - "drifiting controls"?
> - "degradation of ... heating and cooling systems (efficiency)" - boiler
> efficiency, chiller effiency, fan efficiency ...?
> - "damper control" - leakage?
>
> We can't model these things without being specific about how they affect
> the performance of different items of equipment at different operating
> points, which usually means have a physical or mechanistic description
> of what is causing the degradation. If we don't have this foundation,
> the results could be very misleading.
>
> Phil
>
> noelcrrl wrote:
>
> > Philip,
> >
> > Thanks for your reply. I am trying to model the degradation of
> > controls systems (drifting controls), heating and cooling systems
> > (efficiency), and air distribution systems as a function (leakage,
> > damper control, etc.) as a function of time.
> >
> > Regards,
> > Noel
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > <mailto:EnergyPlus_Support%40yahoogroups.com>, Philip Haves <phaves@...>
> > wrote:
> > >
> > > What sort of degradation would you like to model? Do you have
> > specific
> > > causal mechanisms in mind: leaking valves and dampers, drifting
> > sensors ...?
> > >
> > > noelcrrl wrote:
> > >
> > > > Hi. I am trying to model a VAV HVAC system and study its
> > performance
> > > > as a function of time. In essence, I am trying to model the
> > > > degradation of a HVAC system over time. I am aware that
> > EnergyPlus is
> > > > limited and in some ways not capable of simulating the
> > degradation of
> > > > an HVAC in terms of performance and efficiency. However, would
> > it be
> > > > possible to input a defined efficiency versus time curve into
> > > > EnergyPlus that would represent the HVAC system efficiency as a
> > > > function of time? If this is possible, what process should I
> > follow
> > > > to accomplish this? Also, is this the right approach or should I
> > go
> > > > about this another way? And finally, is there a resource that I
> > could
> > > > tap into that would have a number of efficiency versus time
> > curves
> > > > that could be helpful.
> > > >
> > > > Thanks in advance for your help!
> > > >
> > > >
> > >
> > >
> > > --
> > > *****************************************
> > > Philip Haves
> > > Leader, Commercial Building Systems Group
> > > Lawrence Berkeley National Laboratory
> > > 1 Cyclotron Road Bldg 90R3111
> > > Berkeley, CA 94720-8134
> > > Tel: (510) 486 6512
> > > Fax: (510) 486 4089
> > > *****************************************
> > >
> >
> >
>
>
> --
> Philip Haves
> Leader, Commercial Building Systems Group
> Lawrence Berkeley National Laboratory
> 1 Cyclotron Road Bldg 90R3111
> Berkeley, CA 94720-8134
> Tel: (510) 486 6512
> Fax: (510) 486 4089
>
>
>
>
>
>
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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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