[EnergyPlus_Support] Re: Problem with results of a simulation

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, YuanLu Li <yli006@...> wrote:
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> After running your IDF, I found that you have many unusual features. The DesignDay temperature range is zero. The temperature is constant for the whole day. Infiltratin is very high, so that Winter cold air and Summer hot air are added to your load. You have very high internal load in Summer. Therefore high cooling rate. Check the schedule for Winter. Window heat gain and loas are in the order of 5kw each This adds to your heating and cooling load. Ground temperature was not endered and assumed to be 18°C. This is keeping your zone temperature high in Winter. No heating required at night. (higher than 10°C)=========================I have change some of the schedules and designDay data, and report variables to test the simulation. The infiltration is turned off, and the DesignDay data is from the .ddy file. OA minimum fow is also zero. The heating and cooling rate are now accountable. the .csv and .idf are attached. ====================If you are learning to design the building do not use fancy schedules, people, clothings, etc. Make sure that the building is cool in Summer and warm in Winter, and then add a little HVAC to increase comfort. Simulation with different equipment will not improve energy usage.
> Dr. Li P.S. for Richard Are you saying that if the actual type 4 on/off (high/low) setpoint is used for sizing, the maximum available flow rate would be higher, and a temperature change can be met faster. When the peak flow is limited, the fast temperture rise becomes a rounded temperature rise in the simulation, as in most VAV cases.
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> From: RRaustad@...
> Date: Mon, 21 Nov 2011 16:42:40 -0500
> Subject: Re: [EnergyPlus_Support] Re: Problem with results of a simulation
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> The thermostat temperature schedules should not use setback/setup
> during sizing periods (i.e., SummerDesignDay and WinterDesignDay
> temperature set point should be constant) so that the autosized flow
> rate is not excessively high. Then during the actual simulation,
> when a setback/setup temperature schedule IS used, the peaks during
> "thermostat temperature set up" may not be as high.
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> Schedule:Compact,
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> Htg-SetP-Sch, !- Name
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> Temperature, !- Schedule Type Limits Name
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> Through: 12/31, !- Field 1
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> For: Weekends HoliDay, !- Field 2
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> Until: 7:00,12.8, !- Field 3
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> Until: 14:00,21.1, !- Field 5
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> Until: 24:00,12.8, !- Field 7
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> For: SummerDesignDay, !- Field 9
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> Until: 24:00,12.8, !- Field 10
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> For: WinterDesignDay, !- Field 12
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> Until: 24:00,21.1, !- Field 13
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> For: AllOtherDays, !- Field 15
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> Until: 7:00,12.8, !- Field 16
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> Until: 19:00,21.1, !- Field 18
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> Until: 24:00,12.8; !- Field 20
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> Schedule:Compact,
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> Clg-SetP-Sch, !- Name
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> Temperature, !- Schedule Type Limits Name
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> Through: 12/31, !- Field 1
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> For: Weekends HoliDay, !- Field 2
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> Until: 7:00,40.0, !- Field 3
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> Until: 14:00,23.9, !- Field 5
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> Until: 24:00,32.2, !- Field 7
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> For: SummerDesignDay, !- Field 9
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> Until: 24:00,23.9, !- Field 10
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> For: WinterDesignDay, !- Field 12
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> Until: 24:00,40.0, !- Field 13
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> For: AllOtherDays, !- Field 15
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> Until: 7:00,40.0, !- Field 16
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> Until: 19:00,23.9, !- Field 18
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> Until: 24:00,40.0; !- Field 20
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> On 11/21/2011 4:31 PM, YuanLu Li wrote:
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> Check your schedules, internal load, infiltration and
> ventilation, if any.
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> Send me the IDF. I will have a look at it, if I have
> time.
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> Dr. Li
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> To:
> EnergyPlus_Support@xxxxxxxxxxxxxxx
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> From: nachogo27@...
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> Date: Mon, 21 Nov 2011 19:35:50 +0000
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> Subject: [EnergyPlus_Support] Re: Problem with results
> of a simulation
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> Thanks in advance Dr.Li,
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> It is a simple simulation without HVAC systems,I
> have only added the Ideal Load
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> System.
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> But I have a very high peak load in heating mode
> when the the target temperature
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> for my ideal system changes from 12.8ºC to 21.1ºC
> at 6:00am. How? by
> schedule?
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> It seems that my Ideal Load System is switched off
> because the zone temperature
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> is near to 18ºC (the target temperature is
> 12.8ºC,therefore the Ideal System is
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> off). Real zone
> temperature is never that low. Do you mean the
> outdoor temperature is at 12.8°C
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> But at 6:00am the target temperature changes to
> 21.1ºC,the Ideal System
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> switchs on.This is the moment when I got a very
> high peak(For example,I had a
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> peak of 80000W at 6:00am and after this peak the
> load is maintained near to
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> 8000W during only one hour more,after that I dont
> need more heating).
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> That is normal. You are
> changing everything in the zone from 12.8°C to
> 21°C. After that, you are only maintaining the
> temperature to balance the incremental solar and
> inter load.
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> The flow rate which is autosized is very high,I've
> tried to manual size it to 2
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> m3/s but it didn't work.
> What flow rate are talking about?
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> I've uploaded the idf file to
> _Problem_Submittals folder,if you can take a look
> it would be great.
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> Thanks,
>
> Ignacio Gomis
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> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx,
> YuanLu Li yli006@ wrote:
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> > I am not sure what is your "air heating
> rate". As your heating load is high during the
> day, from 6 am, may be you are reporting some roof
> temperature related variables. A 750m2 roof can be
> receiving 750kW of heat from the sun. (Assuming
> 1KW/m2.) The variation of this intensity can be
> found by listing the solar radiation related
> variables in your simulation. If you will post or
> send me the IDF, I will have a look at it. Dr. Li
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> --
> 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
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