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Re: [EnergyPlus_Support] Re: A problem of Sensible Heating/Cooling Rate
0. Definitions of these variables appear beginning on p. 180 (pdf p. 210) of
the Input Output Reference. I will admit the definitions are quite brief.
The answers to the remaining questions can all be explained by reviewing the
zone thermostat setpoint, zone temperatures, and system supply air temperatures.
1. No. On this day, the system fan is on for all hours with some amount of
outside air at all times (smaller at night), the zone heating setpoint is 12.8C
at night and switches to 21.1C at hour 8, the maint heating coil is controlled
to supply 16C supply air. The zone temperature in the early morning is
floating between 15.7 and 16.2C, and some fraction of lights and equipment are
always on adding heat to the space. Whenever the zone is >16C, this variable
will report cooling; <16C heating.
2. At hour 8, the thermostat setpoint increases to 21.1C, so the heating
delivered is large to recover from setback.
3. It is not simultaneous at the HVAC system time step. The values reported
in the example are averaged or summed over the zone time step which may contain
multiple system time steps. As explained before, you must report these
variables at the "detailed" reporting frequency to see every HVAC system time
step.
4. The zone is floating down to the setback temperature while the system
continues to supply minimum flow at 16C. If the zone is >16C, the system is
cooling the space by default until the thermostat calls for heat to maintain
the setback temperature.
Mike
On 9 Nov 2004, at 2:47, hbn_pch wrote:
>
>
> Dear all:
> Thanks for Mike's kind reply.
> I have searched the document and find it just lists the name of the
> variables.There is no specification in the document.
> For convenience,I list the values for the whole day in 14th,Jan.
> I use Space-1 for instance.From 1am to 7am,the Zone/Sys Cooling Rate
> values are:210w,217w,220w,215w,218w,219w,208w.The Zone/Sys Heating
> Rate values are 0.At 8am,The Zone/Sys Heating Rate value is 2519w,and
> the Zone/Sys Cooling Rate is 0.At 9am,The Zone/Sys Heating Rate value
> is 167w and the Zone/Sys Cooling Rate value is 62 w.For the remainer
> hour,the Zone/Sys Cooling Rate value
> are:517w,558w,574w,525w,550w,591w,573w,546w,542w,457w,381w,318w,270w,2
> 29w,217w,0w.And The Zone/Sys Heating Rate value is 0.
> Then problems come:
> Problem 1:Why there is only Zone/Sys Cooling Rate during 1am to 7am?
> And during 1am to 7am,the Zone/sys Air Temp values increase a little
> sometimes,if the Zone/sys Air Temp increase,The Zone/sys Heating Rate
> value must be positive?
>
> Problem 2:Why the the Zone/Sys Heating value is so big?
>
> Problem 3:Why the the Zone/Sys Heating and The Zone/Sys Cooling Rate
> exist simultaneous and the values is so small?
>
> Problem 4:Why there is only Zone/Sys Cooling Rate during the remainer
> hours.And in front hours of the remain,the system is on its occpuied
> period,but the Zone/Sys Heating Rate value is 0.Why?
>
> Thanks for all your kind help!
> pch
>
>
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte"
> <mjwitte@g...> wrote:
> > The Zone/Sys Heating/Cooling report variables are described in the
> Input Output
> > Reference, as are most report variables. Search the docment for
> the variable
> > name to find a description.
> >
> > In this simulation, the thermostat has a setback schedule, so that
> is why the
> > zone temperatures are cool in the unoccupied period. Also, during
> winter, the
> > system has been scheduled to run the fan around the clock. The
> minimum outside
> > air schedules is set to 2% during unoccupied hours, so the system
> always brings
> > in some fresh air. During the hours that you refer to that show
> values for
> > Zone/Sys Sensible Cooling, the system is cooling the space because
> the mixed
> > air is cooler than the zone air. Remember that the zone/sys
> heating/cooling
> > variables indicate what the system delivered to the zone, not what
> the coils
> > are doing.
> >
> > Mike
> >
> >
> > On 5 Nov 2004, at 3:09, hbn_pch wrote:
> >
> > >
> > >
> > > Dear all:
> > > I start a simulation of the example of 5ZoneEngChill.idf
> attached
> > > to the EnergyPlus.
> > > For analysis,I add a boiler parameter of Boiler Gas Consumption
> > > Rate in the report parameter.I discover that there is only
> Sensible
> > > Cooling Rate values from 1am to the 7am.But at 8am there is only
> > > Sensible Heating Rate values,and these values are very
> big.Whereas,in
> > > 9am,Sensible Cooling Rate value and Sensible Heating Rate value
> exist
> > > simultaneous and the two values are very small.For remainder
> > > hours,there is Sensible Cooling Rate only.
> > > From 1am to 7am,the Zone/Sys Air Temp values are approximately
> > > 17C,and from 8am to 6pm the Zone/Sys Air Temp values are
> > > approximately 21C.Then the Zone/Sys Air Temp values decrease by
> hour.
> > > So I'm puzzled.I can't find the reasonable explain.I even did't
> > > know what do Zone/Sys Heating/Cooling Rate and Zone/Sys Air Temp
> mean.
> > >
> > > Thanks for all your kind help!
> > > pch
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > 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.
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> >
> > ========================================================
> > Michael J. Witte, GARD Analytics, Inc.
> > EnergyPlus Testing and Support
> > EnergyPlus-Support@g...
>
>
>
>
>
>
> 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.
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
>
========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support
EnergyPlus-Support@xxxxxxxx
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