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Re: [EnergyPlus_Support] Fwd: Re: Cooling set-point not fully achieved
Ana, change the frequency of the report variables to "detailed". You
will notice that the loss of set point control occurs when the program
is simulating at a reduced time step (shorter than 15 minutes). And it
doesn't happen for the entire duration of the shortened time step
period. This is exactly the problem we have been seeing. When any zone
temperature changes by more than 0.03C, the simulation tries again at a
shorter time step (so some load changed quickly to make the zone
temperature change quickly). When this occurs, the prediction of zone
loads are somewhat less accurate. We are working on this and hope to
have a resolution soon. I haven't looked at your input closely enough to
know why this only happens in 1 zone. Is it possible for you to "smooth"
out the people, equipment and lighting loads (to eliminate step
functions in load) in zone 43515? For instance, it takes several minutes
for occupancy to change in a zone, and with diversity of equipment,
those loads could also be assumed to change over several minutes. You
could change to using compact schedules to provide a "smoother"
transition from 1 minute to the next (or from 1 15-min period to the
next), maybe that would help. I still think your results are not
impacted all that much, but I also know that when someone sees the loss
of set point, the results come into question.
Here's an example of smoothing out a schedule, I'm not saying this will
work, but if you are really determined to eliminate this problem, it's
worth a try. You have schedules for occupancy, equipment, lighting,
infiltration, etc. Even if your schedules are "fixed" by some standard,
smoothing them out quickly (in 15 minute intervals) , while still
conform to the intent of the schedule.
Also, what happened when you tried to simulate at 1 hour time steps?
Your schedule:
DAYSCHEDULE,
School_People_WeekDay, !- Name
Fraction, !- ScheduleType
0, !- Hour 1
0, !- Hour 2
0, !- Hour 3
0, !- Hour 4
0, !- Hour 5
0, !- Hour 6
0, !- Hour 7
0, !- Hour 8
0.05, !- Hour 9
0.9, !- Hour 10
1, !- Hour 11
1, !- Hour 12
1, !- Hour 13
0.9, !- Hour 14
0.9, !- Hour 15
1, !- Hour 16
1, !- Hour 17
1, !- Hour 18
0.8, !- Hour 19
0.1, !- Hour 20
0, !- Hour 21
0, !- Hour 22
0, !- Hour 23
0; !- Hour 24
My suggestion:
SCHEDULE:COMPACT,
School_People_Yearly, !- Name
Fraction, !- ScheduleType
Through: 31 Dec, !- Complex Field #1
For: Weekdays SummerDesignDay, !- Complex Field #2
Until: 09:00, !- Complex Field #3
0, !- Complex Field #4
Until: 09:15, !- Complex Field #5
0.05, !- Complex Field #6
Until: 09:30, !- Complex Field #7
0.25, !- Complex Field #8
Until: 09:45, !- Complex Field #9
0.75, !- Complex Field #10
Until: 10:00, !- Complex Field #11
0.8, !- Complex Field #12
Until: 10:15, !- Complex Field #13
0.9, !- Complex Field #14
Until: 14:00, !- Complex Field #15
1, !- Complex Field #16
Until: 14:15, !- Complex Field #17
0.95, !- Complex Field #18
Until: 16:00, !- Complex Field #19
0.9, !- Complex Field #20
Until: 16:15, !- Complex Field #13
0.95, !- Complex Field #14
Until: 19:00, !- Complex Field #15
1, !- Complex Field #16
Until: 19:15, !- Complex Field #17
0.9, !- Complex Field #18
Until: 19:30, !- Complex Field #19
0.7, !- Complex Field #20
Until: 19:45, !- Complex Field #15
0.5, !- Complex Field #16
Until: 20:00, !- Complex Field #17
0.3, !- Complex Field #18
Until: 21:00, !- Complex Field #19
0.1, !- Complex Field #20
Until: 24:00, !- Complex Field #19
0.0, !- Complex Field #20
For: Weekends, !- Complex Field #21
Until: 24:00, !- Complex Field #22
0, !- Complex Field #23
For: Holidays, !- Complex Field #24
Until: 24:00, !- Complex Field #25
0, !- Complex Field #26
For: WinterDesignDay AllOtherDays, !- Complex Field #27
Until: 24:00, !- Complex Field #28
0; !- Complex Field #29
Richard Raustad wrote:
>
> Well, I would rather see a graph, but from what you describe, yes it does.
>
> If you wish, email a graph in the spreadsheet (save it as xls) to:
> rraustad@xxxxxxxxxxxx <mailto:rraustad%40fsec.ucf.edu>
>
> anarui.oliveira wrote:
> >
> > Differences go up to 1ºC. Does it fit the behaviour of the problem
> > you describe?
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > <RRaustad@...> wrote:
> > >
> > > I have looked at this control issue before. I don't think it's the
> > > mixing objects or other zone loads. And your offset from the set
> > point
> > > should be pretty small. Not to worry, the overall annual energy use
> > > should be pretty close. Beside, if you run this building using a
> > > different building simulation tool, your likely to get a different
> > > answer. And I believe the difference in these answers will be
> > greater
> > > than the difference in annual energy use due to the set point
> > offset. If
> > > it happens all the time, adjust your set point so the "average"
> > zone
> > > temperature is near your target temperature.
> > >
> > > anarui.oliveira wrote:
> > > >
> > > > Could the mixing objects or anything like that contribute to this
> > > > problem? Or some definitions such as humidity ratios or the
> > like?...
> > > > Getting worried here... the aim was exactly to predict the energy
> > > > consumption of a building throughout a year (for official, legal
> > > > purposes)...
> > > >
> > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > <mailto:EnergyPlus_Support%40yahoogroups.com>, "anarui.oliveira"
> > > > <anarui.oliveira@> wrote:
> > > >
> > > > Is this problem equally likely to happen if I use a Purchased Air
> > > > approach?
> > > >
> > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > > > <RRaustad@> wrote:
> > > > >
> > > > > You could try increasing the time step in hour. I have no other
> > > > > suggestions. This is a known issue and we are working to
> > correct it.
> > > > >
> > > > > anarui.oliveira wrote:
> > > > > >
> > > > > > That field is already set to 1, and time step in hours is set
> > to
> > > > 4.
> > > > > >
> > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > > > > > <RRaustad@> wrote:
> > > > > > >
> > > > > > > What you describe is not a capacity issue, it is related to
> > the
> > > > > > > prediction of loads. If you add the report variable
> > > > for "Zone/Sys
> > > > > > > Sensible Load Predicted" and set the report variable
> > frequency
> > > > to
> > > > > > > detailed, you will see why this is happening. Try reducing
> > the
> > > > > > Minimum
> > > > > > > System Time Step in the System Convergence Limits object.
> > You
> > > > > > probably
> > > > > > > will not eliminate the problem, but it should get better.
> > > > > > >
> > > > > > >
> > > > > > > anarui.oliveira wrote:
> > > > > > > >
> > > > > > > > What if, in a similar (heating) case, water flow doesn't
> > > > reach the
> > > > > > > > maximum when the problem occurs, and increasing the air
> > flow
> > > > > > causes
> > > > > > > > further departure from temperature setpoint?...(Less than
> > > > about
> > > > > > 1.5
> > > > > > > > times the auto-sized air flow also leads to poorer
> > setpoint
> > > > > > > > tracking); reported air flow is always equal to the
> > constant
> > > > > > volume
> > > > > > > > fan flow, and ouside air flow rate is (and must be) user
> > > > > > specified.
> > > > > > > >
> > > > > > > > Regards,
> > > > > > > > Ana.
> > > > > > > >
> > > > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard
> > Raustad
> > > > > > > > <RRaustad@> wrote:
> > > > > > > > >
> > > > > > > > > Then try again to manually size the coil in the problem
> > > > zone to
> > > > > > > > twice
> > > > > > > > > the size reported in the eio file. Also increase the air
> > > > flow
> > > > > > rate
> > > > > > > > for
> > > > > > > > > that fan coil unit and fan to twice the autosized
> > value. If
> > > > > > htis is
> > > > > > > > > happening in more than 1 zone, then just pick 1 for now
> > to
> > > > test
> > > > > > > > this out.
> > > > > > > > >
> > > > > > > > > Then tell me what happens to the maximum zone
> > temperature.
> > > > Did
> > > > > > the
> > > > > > > > > maximum zone temperature go down? Also tell me if the
> > water
> > > > flow
> > > > > > > > rate is
> > > > > > > > > at a maximum when the zone temperature exceeds the set
> > > > point.
> > > > > > You
> > > > > > > > can
> > > > > > > > > report "System Node VolFlowRate" for the coil water
> > inlet
> > > > node
> > > > > > and
> > > > > > > > fan
> > > > > > > > > coil air inlet node to easily match volumetric flow rate
> > > > with
> > > > > > your
> > > > > > > > inputs.
> > > > > > > > >
> > > > > > > > > This just sounds like a sizing issue and should be
> > easily
> > > > > > resolved.
> > > > > > > > >
> > > > > > > > > anarui.oliveira wrote:
> > > > > > > > > >
> > > > > > > > > > Apparently, yes, but I set it to autosize (and I
> > think I
> > > > > > already
> > > > > > > > did
> > > > > > > > > > a trial with a larger, user-defined, water flow
> > rate)...
> > > > > > > > > >
> > > > > > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard
> > > > Raustad
> > > > > > > > > > <RRaustad@> wrote:
> > > > > > > > > > >
> > > > > > > > > > > I have not looked at your input file, can you tell
> > me
> > > > if the
> > > > > > > > water
> > > > > > > > > > mass
> > > > > > > > > > > flow rate through the fan coil is at a maximum when
> > the
> > > > > > cooling
> > > > > > > > set
> > > > > > > > > > > point is not met?
> > > > > > > > > > >
> > > > > > > > > > > anarui.oliveira wrote:
> > > > > > > > > > > >
> > > > > > > > > > > > Please forgive me for insisting, but I DO have
> > some
> > > > > > urgency on
> > > > > > > > > > this
> > > > > > > > > > > > one...
> > > > > > > > > > > > Again, thanks for any help,
> > > > > > > > > > > > Ana.
> > > > > > > > > > > >
> > > > > > > > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > > > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > > > > > > > > <mailto:EnergyPlus_Support%
> > > > > > > > 40yahoogroups.com>, "anarui.oliveira"
> > > > > > > > > > > > <anarui.oliveira@> wrote:
> > > > > > > > > > > > >
> > > > > > > > > > > > > Hi again.
> > > > > > > > > > > > >
> > > > > > > > > > > > > I'm uploading a new file
> > (Zone36598_cFancoil_exp),
> > > > > > hoping
> > > > > > > > that
> > > > > > > > > > > > someone
> > > > > > > > > > > > > can help me figure out why the cooling setpoints
> > > > are not
> > > > > > > > being
> > > > > > > > > > > > achieved
> > > > > > > > > > > > > for all times when the controls are active
> > (namely
> > > > in
> > > > > > Zone
> > > > > > > > > > 36598).
> > > > > > > > > > > > The
> > > > > > > > > > > > > model consists of Fancoil units created with
> > Compact
> > > > > > HVAC,
> > > > > > > > and
> > > > > > > > > > then
> > > > > > > > > > > > > edited in the expanded file.
> > > > > > > > > > > > > I tried several user-defined and sizing
> > options, but
> > > > > > > > couldn't
> > > > > > > > > > solve
> > > > > > > > > > > > the
> > > > > > > > > > > > > temperature peaks above 25ºC.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Thanks in advance,
> > > > > > > > > > > > > Ana Rui.
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > --
> > > > > > > > > > > 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>
> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>
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> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>>
> > > > > > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
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> > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
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> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>>>
> > > > > > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>
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> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>>
> > > > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>
> > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <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
> <http://www.fsec.ucf.edu>
> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>
> > > > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>>
> > > > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>
> > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <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
> <http://www.fsec.ucf.edu>
> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>
> > > > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <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
> <http://www.fsec.ucf.edu>
> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>
> > <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> <http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>>>
> > > > >
> > > > > UCF - From Promise to Prominence: Celebrating 40 Years
> > > > >
> > > >
> > > > --- End forwarded message ---
> > > >
> > > >
> > >
> > > --
> > > 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> <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 <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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