Re: AW: [EnergyPlus_Support] Design Day Condition

["Michael J. Witte" <mjwitte@xxxxxxxx>]

The design day data in 
C:\EnergyPlus\PreProcess\WeatherConverter\USDesignConditions.csv and 
WorldDesignConditions.csv which is also present in many of the 
EnergyPlus weather files is taken from the 2001 ASHRAE Handbook of 
Fundamentals (2001 HOF), copyright ASHRAE, Inc.  In the 1997 HOF, 
ASHRAE changed from seasonal to annual percentiles for determining 
design conditions and the design values for many locations changed 
slightly.

The design day objects in EnergyPlus\Datasets\BLASTDesignDays.idf are 
 based on ASHRAE design conditions published prior to 1997.  That is 
why you do not see an exact match.  Sorry for the confusion.  We will 
add notes to the dataset file indicating the source and the reason 
for differences.  We are working on producing a dataset file which is 
consistent with the newer ASHRAE data.  

In the newer ASHRAE data, you see percentiles such as 99.6%, 99%, 
0.4%, 1%, etc.  A "1%" value is a temperature which is exceeded for 
1% of the hours in a year.  A "99%" value is a temperature which is 
exceeded for 99% of the hours in a year.  For more details, see the 
2001 ASHRAE Handbook of Fundamentals, Chapter 27.

Mike



On 14 Oct 2002, at 9:22, Alexander Beisteiner wrote:

> Hi Mike
> For example:
> 
> DesignDay,
>     DENVER COLORADO WINTER,  !- DesignDayName
>     -17.22222,  !- Maximum Dry-Bulb Temperature {C}
>      0.0000000E+00,  !- Daily Temperature Range {C}
>     -17.22222,  !- Wet-Bulb Temperature At MaxTemp {C}
>     83361.40,  !- Barometric Pressure {Pa}
>     4.115816,  !- Wind Speed {m/s}
>     169.0000,  !- Wind Direction {deg}
>     0.0000000E+00,  !- Sky Clearness
>     0,  !- Rain Indicator
>     0,  !- Snow Indicator
>     21,  !- Day Of Month
>     1,  !- Month
>     Monday,  !- Day Type
>     0;  !- Daylight Saving Time Indicator
> 
> Comparing the winter design day condition for Colorado in the idf-file
> with the design day conditions in the E+ directory
> EnergyPlus/PreProcess/WeatherConverter/DesignConditions I cannot find
> correlation between the Maximum Dry-Bulb Temperature and Wind
> Direction (see example of the idf above). Further, there is not
> correlation between the summer design day conditions either: for
> example the Maximum Dry-Bulb Temperature and there is no wind speed
> information in the
> EnergyPlus/PreProcess/WeatherConverter/DesignConditions directory. In
> addition, what do the percentage classifications in the design
> condition files mean: 40%, 99.6%, 1%, etc.?
> 
> I would appreciate your comment.
> Regards
> 
> -----Ursprüngliche Nachricht-----
> Von: Michael J. Witte [mailto:mjwitte@xxxxxxxx] 
> Gesendet: Freitag, 11. Oktober 2002 17:42
> An: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Betreff: Re: [EnergyPlus_Support] Design Day Condition
> 
> Please give an example.  Mike
> 
> On 11 Oct 2002, at 16:38, Alexander Beisteiner wrote:
> 
> > Dear Sir/Madam
> > Why is the design day condition in the .idf-file different from the
> > weather file? I am looking forward to your reply. Regards
> > 
> > Alexander Beisteiner
> > __________________________________
> > alexander.beisteiner@xxxxxxxxxxxxxxxxxx
> > Forschungs- und Technologietransfer
> > Pinkafeld GmbH
> > Steinamangerstrasse 21
> > 7423 Pinkafeld
> > 
> > http://www.fh-pinkafeld.ac.at <http://www.fh-pinkafeld.ac.at/> Tel.:
> > 0043/3357/45370 Fax: 0043/3357/45370/1010
> > 
> > 
> 
> 
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