Re: [EnergyPlus_Support] Re: Difference between RunPeriod and SizingPeriod:weatherfiledata

2009/10/14 YuanLu Li <yli006@xxxxxxxxxxx>

Hi, Hu Jia

I do not have the exact answer. I only know that the values used for calculation may be different for the sizing periods and the run weather file periods.

As the day of the week is settable in the weather file, when you use a section of the weather file, the program may not bother to calculate the day of the week, as the sizing algorithm is to find the maximum and minimum conditions.

The date set in the DesignDay object does not mean that it will use the weather file data of the same date. The date is taken from the statistical data and from the .ddy file. You can set different day in a number of different DesignDay objects (with different object name) to test your schedules.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: hujia06@xxxxxxxxx
Date: Wed, 14 Oct 2009 01:45:22 +0800

Subject: Re: [EnergyPlus_Support] Re: Difference between RunPeriod and SizingPeriod:weatherfiledata

Hello,  Dr. Li,

I check the Day Type Index and found on the same day, the day type is different. For RunPeriod, I set "Date of Week for start day" is to use the weather file. And that of SizingPeriod:WeatherFile is blank.

Why is the data type different for the same day? Is that because the two objects use different years in the weather file?

Thank you.

JH

2009/10/14 YuanLu Li <yli006@xxxxxxxxxxx>

You may also turn on the report on:

Zone,Average,DayType Index []
Zone,Average,Schedule Value []

to see whether the same date uses the same day type and schedules.

The day can be set in the DesignDay object. I am not sure whether the sizing run period would start with day type 1 and so may be different from the weather file run.   The weather file day of the week is set at the line after the Comment2, the Data Period line.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: linda@xxxxxxxxxxxxxx
Date: Tue, 13 Oct 2009 06:59:46 -0600
Subject: Re: [EnergyPlus_Support] Re: Difference between RunPeriod and SizingPeriod:weatherfiledata

There was a bug in V3.1, try downloading V4.0 and see if you still have problems.

Note, too, however, that daylighting is not run for Sizing periods -- with your change in electric power, if you have daylighting, this might be the answer.

At 09:41 PM 10/12/2009, hjtju2002 wrote:

Dear all,

I define in my input file the RunPeriod is the whole year. And I also set up the SizingPeriod:weatherFileDays is only two month (Jan 1st to March 1st). Both of them use the same weath file.

But after simulation, I found that the results of the same day calculated using RunPeriod and SizingPeriod are different. For example, on Feb 1st, the electric power is 75 for RunPeriod and 227 for SizingPeriod.

Could anyone explain why they are different?

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