You need to explain why you want to do designDay sizing for more than one day. I may then help you to explore more on the DesignDay sizing or simulation.
In a uniform sine wave, there is only one peak value. It does not matter how many cycle you look at, it will give you the same peak value.
When you have a distorted sine wave, or the sum of a number of sine waves, then the peak value can change. Looking for a few consequtive cycles may not give you the maximum peak value.
The measurement then relies on statitistical approach, using peak to average ratio, fast rise and slow decay by integration, etc. Power based measurement are used to sum a number of similar waveform together, loading factor.
Then the maximum peak is defined for a specific type of waveforms.
With TMY, the data cover a period of one year and have a daily cycle. In general, the Winter has lower temperature and Summer has higher temperature as a day time maximum in the Northern hemisphere.
ASHRAE IWEC has a certain statistical information of the weather file as the header of the weather file.
The more detailed statistical data is in the .stat file. For sizing application, the .ddy file has the EPlus DesignDay objects for heating and cooling season, at various level of high and low probability of occurance. The follow is an example of a heating DesignDay object listing.
! Los Angeles Intl Arpt_CA_USA Annual Heating Design Conditions Wind Speed=2.4m/s Wind Dir=90
! Coldest Month=JAN
! Los Angeles Intl Arpt_CA_USA Annual Heating 99.6%, MaxDB=6.9°C
SizingPeriod:DesignDay,
Los Angeles Intl Arpt Ann Htg 99.6% Condns DB, !- Name
6.9, !- Maximum Dry-Bulb Temperature {C}
0.0, !- Daily Dry-Bulb Temperature Range {deltaC}
6.9, !- Humidity Indicating Conditions at Maximum Dry-Bulb
100965., !- Barometric Pressure {Pa}
2.4, !- Wind Speed {m/s}
90, !- Wind Direction {deg}
0.00, !- Sky Clearness
0, !- Rain Indicator
0, !- Snow Indicator
21, !- Day of Month
1, !- Month
WinterDesignDay, !- Day Type
0, !- Daylight Saving Time Indicator
WetBulb; !- Humidity Indicating Type
!- =====================
Annual Heating 99.6%, MaxDB=6.9°C is the special characteristic of the DesignDay object.
It means that only 0.4% of the days in the year may be colder than this condition. Note also that it has no sun during the day.
There may be more than 16 different DesignDay object files in a .ddy file for one locaion with different combination of humidity indicating type, and dry bulb/ % values.
There are a few more fields below the WetBulb.
DesignDay sizing object may originally specially designed for sizing of HVAC equipment.
I am using it for running current locally measured environment data, as the fields are easier to change and modify..
Using weather file for sizing is not really adviceable, unless you know the content of the weather file well.
Using a shorter section of weather file to run normal simulation is to save time, while debugging.
The reason to use normal weather file simulation is that the Sizing run using DesignDay assumes that the warming up is using the same data until the two midnight results matches. Separate warm up run is done for every DesignDay object.
In the run peiod simulation, the zone sizing, system sizing, and plant sizing is done, and then the weather file data is used one day after another till the end of the day chosen, the process can be asked to repeat a few times to verify that the data initializing process is not affecting the first day's result.
Many users are not following this sizing and run period procedure and get unexpected reaults.
Because I also use the DesignDay sizing run for other purposes, that was why I ask you the reason for doing multiple designDay run.
I am doing multiple DesignDay object sizing run using different DesignDay data on different date to study the effect of sun beam through windows. No HVAC equipment is involved in my studies.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: malzuu@xxxxxxxx
Date: Wed, 4 Apr 2012 12:00:01 +0000
Subject: [EnergyPlus_Support] designday used on more days
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
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 currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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In a uniform sine wave, there is only one peak value. It does not matter how many cycle you look at, it will give you the same peak value.
When you have a distorted sine wave, or the sum of a number of sine waves, then the peak value can change. Looking for a few consequtive cycles may not give you the maximum peak value.
The measurement then relies on statitistical approach, using peak to average ratio, fast rise and slow decay by integration, etc. Power based measurement are used to sum a number of similar waveform together, loading factor.
Then the maximum peak is defined for a specific type of waveforms.
With TMY, the data cover a period of one year and have a daily cycle. In general, the Winter has lower temperature and Summer has higher temperature as a day time maximum in the Northern hemisphere.
ASHRAE IWEC has a certain statistical information of the weather file as the header of the weather file.
The more detailed statistical data is in the .stat file. For sizing application, the .ddy file has the EPlus DesignDay objects for heating and cooling season, at various level of high and low probability of occurance. The follow is an example of a heating DesignDay object listing.
! Los Angeles Intl Arpt_CA_USA Annual Heating Design Conditions Wind Speed=2.4m/s Wind Dir=90
! Coldest Month=JAN
! Los Angeles Intl Arpt_CA_USA Annual Heating 99.6%, MaxDB=6.9°C
SizingPeriod:DesignDay,
Los Angeles Intl Arpt Ann Htg 99.6% Condns DB, !- Name
6.9, !- Maximum Dry-Bulb Temperature {C}
0.0, !- Daily Dry-Bulb Temperature Range {deltaC}
6.9, !- Humidity Indicating Conditions at Maximum Dry-Bulb
100965., !- Barometric Pressure {Pa}
2.4, !- Wind Speed {m/s}
90, !- Wind Direction {deg}
0.00, !- Sky Clearness
0, !- Rain Indicator
0, !- Snow Indicator
21, !- Day of Month
1, !- Month
WinterDesignDay, !- Day Type
0, !- Daylight Saving Time Indicator
WetBulb; !- Humidity Indicating Type
!- =====================
Annual Heating 99.6%, MaxDB=6.9°C is the special characteristic of the DesignDay object.
It means that only 0.4% of the days in the year may be colder than this condition. Note also that it has no sun during the day.
There may be more than 16 different DesignDay object files in a .ddy file for one locaion with different combination of humidity indicating type, and dry bulb/ % values.
There are a few more fields below the WetBulb.
DesignDay sizing object may originally specially designed for sizing of HVAC equipment.
I am using it for running current locally measured environment data, as the fields are easier to change and modify..
Using weather file for sizing is not really adviceable, unless you know the content of the weather file well.
Using a shorter section of weather file to run normal simulation is to save time, while debugging.
The reason to use normal weather file simulation is that the Sizing run using DesignDay assumes that the warming up is using the same data until the two midnight results matches. Separate warm up run is done for every DesignDay object.
In the run peiod simulation, the zone sizing, system sizing, and plant sizing is done, and then the weather file data is used one day after another till the end of the day chosen, the process can be asked to repeat a few times to verify that the data initializing process is not affecting the first day's result.
Many users are not following this sizing and run period procedure and get unexpected reaults.
Because I also use the DesignDay sizing run for other purposes, that was why I ask you the reason for doing multiple designDay run.
I am doing multiple DesignDay object sizing run using different DesignDay data on different date to study the effect of sun beam through windows. No HVAC equipment is involved in my studies.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: malzuu@xxxxxxxx
Date: Wed, 4 Apr 2012 12:00:01 +0000
Subject: [EnergyPlus_Support] designday used on more days
Hi,
i would like to use a sizingperiod:designday on more than a singleday simulation.
I tried on different ways but with no results.if a build more sizingperiod:day the simulation do more single days while i have to do a week with the same single sizingperio:day object.
i ask if someone know how do that o for an example.
thnks in advance for any suggestions
Best Regards
i would like to use a sizingperiod:designday on more than a singleday simulation.
I tried on different ways but with no results.if a build more sizingperiod:day the simulation do more single days while i have to do a week with the same single sizingperio:day object.
i ask if someone know how do that o for an example.
thnks in advance for any suggestions
Best Regards
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
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 currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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