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RE: [EnergyPlus_Support] Re: Confusion about Eplus output.
I have never seen an "anomalous" building that did not have a specific reason
for not converging. Typical causes are extremely heavy thermal mass (such as
concrete which is 1m thick) or insufficient HVAC or other heat loss modes to
remove heat from the zone. For example, a zone with no exterior surfaces, no
infiltration, and an HVAC system with capacity smaller than the internal gains
will simply get hotter and hotter and hotter on each successive warmup day.
Mike
On 23 Feb 2007 at 9:00, Albert Sitorus wrote:
> Dear Linda and Kooi,
>
> I run 1ZoneEvapCooler.idf with design days and weather file. The zone has
> been added quite a big load which consists of electric equipment, interior
> lighting and people. For Electric equip., its design is 569W. Interior lighting
> is 761.5W. The number of max number of people is 2. Kooi, are these items what
> you added with standard schedules?
>
> If you run this file using design days without interior lighting, electric
> equipment and people loads, it would run without any convergence problem. When
> you add the other loads using design days, it will cause the convergence problem
> even with 1000 warm-up days. On the other hand if you run this file with
> interior lighting, electric equipments and people loads using weather file, then
> the convergence problem will disappear.
>
> It seems like increasing warm-up days will not solve the convergence
> problem. As stated in the input output reference, increasing warm-up days
> will not necessarily solve a convergence problem. There may be anomalous
> buildings that will have convergence problem. The additional loads are quite
> large for a zone that is surrounded by construction materials with high thermal
> absorptance which almost represent black bodies. This might be one of those
> anomalous buildings. Even though this is a fictional building. Therefore, the
> walls absorb heat from all those heat loads, and then release it as a day wears
> on. The HVAC system can't cool the building enough to get the convergence. As
> stated in final error summary, point 2. It would be nice to know from which day
> the convergence problem occurs (summer or winter days).
>
> My hypothesis is not 100% correct but it makes sense to me. My hypothesis
> would be a mood point if the schedules for these loads were extreme. In my file,
> the schedules are standard. Please let me know if my hypothesis was in correct
> or not making sense. I am very curious what you guys think. My original problems
> were Eplus output and air loop total heating and cooling energies that don't
> make sense. I solved the output problem, thanks to Brent Griffith, but the air
> loop total heating and cooling energies problem still persist......
>
> Thank you for your time and help, I appreciate them greatly.
>
> Albert Sitorus.
>
>
>
> >From: "kooi" <kooi@xxxxxxxxxxxxxxxx>
> >Reply-To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> >To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
> >Subject: RE: [EnergyPlus_Support] Re: Confusion about Eplus output.
> >Date: Thu, 22 Feb 2007 12:54:04 +0800
> >
> >My apologies, if my earlier message was not specific enough. Part of the
> >error message I got from the err file, using Denver weather file was
> >
> >
> >
> >Loads Initialization did not Converge
> >
> > ************* ..1) very high thermal mass such as very thick concrete
> >(solution: increase max number of warmup
> >
> > ************* .. days in the BUILDING object);
> >
> >
> >
> >I changed the warm up days in the BUILDING object to 1000 but the above
> >persisted.
> >
> >
> >
> >Kind regards
> >
> >ooi
> >
>
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support
EnergyPlus-Support@xxxxxxxx
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