RE: [EnergyPlus_Support] Re: Problem with results of a simulation

There is nothing really wrong with the IDF.

You have infiltration to give you the air flow rate.

200kW cooling rate and 15kw heating rate is normal, for the two zones side by side with many windows.

Simplify or display your schedule values, and you will understand what is happening.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: RRaustad@xxxxxxxxxxxx
Date: Mon, 21 Nov 2011 16:42:40 -0500
Subject: Re: [EnergyPlus_Support] Re: Problem with results of a simulation

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.

Schedule:Compact,
    Htg-SetP-Sch,            !- Name
    Temperature,             !- Schedule Type Limits Name
    Through: 12/31,          !- Field 1
    For: Weekends HoliDay,   !- Field 2
    Until: 7:00,12.8,        !- Field 3
    Until: 14:00,21.1,       !- Field 5
    Until: 24:00,12.8,       !- Field 7
    For: SummerDesignDay,    !- Field 9
    Until: 24:00,12.8,       !- Field 10
    For: WinterDesignDay,    !- Field 12
    Until: 24:00,21.1,       !- Field 13
    For: AllOtherDays,       !- Field 15
    Until: 7:00,12.8,        !- Field 16
    Until: 19:00,21.1,       !- Field 18
    Until: 24:00,12.8;       !- Field 20

Schedule:Compact,
    Clg-SetP-Sch,            !- Name
    Temperature,             !- Schedule Type Limits Name
    Through: 12/31,          !- Field 1
    For: Weekends HoliDay,   !- Field 2
    Until: 7:00,40.0,        !- Field 3
    Until: 14:00,23.9,       !- Field 5
    Until: 24:00,32.2,       !- Field 7
    For: SummerDesignDay,    !- Field 9
    Until: 24:00,23.9,       !- Field 10
    For: WinterDesignDay,    !- Field 12
    Until: 24:00,40.0,       !- Field 13
    For: AllOtherDays,       !- Field 15
    Until: 7:00,40.0,        !- Field 16
    Until: 19:00,23.9,       !- Field 18
    Until: 24:00,40.0;       !- Field 20

On 11/21/2011 4:31 PM, YuanLu Li wrote:

Check your schedules, internal load, infiltration and ventilation, if any.

Send me the IDF. I will have a look at it, if I have time.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: nachogo27@xxxxxxxxx
Date: Mon, 21 Nov 2011 19:35:50 +0000
Subject: [EnergyPlus_Support] Re: Problem with results of a simulation

Thanks in advance Dr.Li,
It is a simple simulation without HVAC systems,I have only added the Ideal Load
System.
But I have a very high peak load in heating mode when the the target temperature
for my ideal system changes from 12.8ºC to 21.1ºC at 6:00am.   How? by schedule?

It seems that my Ideal Load System is switched off because the zone temperature
is near to 18ºC (the target temperature is 12.8ºC,therefore the Ideal System is
off).   Real zone temperature is never that low.   Do you mean the outdoor temperature is at 12.8°C

But at 6:00am the target temperature changes to 21.1ºC,the Ideal System
switchs on.This is the moment when I got a very high peak(For example,I had a
peak of 80000W at 6:00am and after this peak the load is maintained near to
8000W during only one hour more,after that I dont need more heating).
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.

The flow rate which is autosized is very high,I've tried to manual size it to 2
m3/s but it didn't work. What flow rate are talking about?

I've uploaded the idf file to _Problem_Submittals folder,if you can take a look it would be great.
Thanks,
Ignacio Gomis

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, YuanLu Li <yli006@...> wrote:
>
>
> 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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