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Re: [EnergyPlus_Support] Re: create EPW weather file [1 Attachment]





I believe I've found out the problem for your conversion. In your def file, you can given the format for the Date as "dd/mm/yyyy",  but the CSV file actually shows is as "dd/mm/yy", i.e., "01/01/15" not "01/01/2015".  When I made that correction, the direct/diffuse split is now coming out reasonably :


I haven't tried changing the def file to "dd/mm/yy", but I wouldn't recommend it unless you like to have more surprises.
By the way, the WMO number for Lausanne is 067100, not 603443. Unfortunately, Lausanne is not in the ASHRAE tables
so you won't get a ddy file. But, if you're interested, I can send you one that I have calculated separately for such stations.

Joe
Joe Huang 	
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx
http://weather.whiteboxtechnologies.com for simulation-ready weather data
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On 6/2/2015 12:14 PM, Linda Lawrie linda@xxxxxxxxxxxxxx [EnergyPlus_Support] wrote:
 

Your input global horizontal looks pretty suspect for months after May.

See attached profile display from dview.

At 09:18 AM 6/2/2015, la.epfl@xxxxxxxxx [EnergyPlus_Support] wrote:


Hello everyone,

I was trying to make sense out of some file transformation I have made. I attach the CSV file, the def file I am using as well as the audit file of the conversion.

I would like to know if everything is fine in the process and clarify some topics.

The original data from the CSV file comes from a weather station measurment and I am automatically transcribing it in the CSV. I am mostly interested in having correct solar radiation interpolation. The station gives me a measurement for sun which I assume to be horizontal global radiation. Does that sound like a reasonable assumption or it might be something else ? I do not have so much information about the weather station it comes from wunderground.com data.

Second, the audit file gives me warnings like:
Warning ** DirectNormalRadiation   1076.0 > max theoretical=   690.6 Wh/m≤ on date= 1/ 1 at hour=14
Does that mean that my original data is not good and should I do something about it ?(I have checked latitude longitude, looks fine).
Then when I look at the EPW file I have created, the direct normal radiation for this hour is not 1076 nor 690 but 829Wh/m2, which I don't really understand.

Finally, I was expecting the direct radiation to be greater than the horizontal global radiation, but that is not what happens in practice. Is that then false ?

Any other advice concerning weather conversion and creating EPW based on measured data is welcome as well :)

Thanks in advance,

Best regards





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Posted by: Joe Huang <yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx>


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