I took a quick look at your files, and I think there's something wrong in the calculation of the direct/diffuse split.
Since your location is in Lausanne, I pulled one of the IWEC2 weather files for Geneva, and compared the two just to see if they're in the same ballpark. The global horizontal for the six months are roughly similar (551 kWh/m2 from your data, 471 for the IWEC2 Geneva), however, the direct normal are very different (171 and 313, respectively). A typical way to see how reasonable are the direct/diffuse split is by comparing the ratio between the global horizontal and the direct horizontal, which is the direct normal * sine (solar altitude). Following are two plots for the two data sets:
from your EPW
from IWEC2 Geneva
The former, frankly, doesn't make much sense. The latter follows a typical Sigismoid curve.
I have no explanation for the problem, which could be either an error in the def file (although the global horizontal
is being input correctly) or something else in the weather.exe, maybe its calculation of the solar angle ?
I can send you the spreadsheet via e-mail if you're interested.
BTW, you should also clean up your input data as much as possible. There are several days with constant
solar values, and several spikes that are beyond possible.
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 http://www.whiteboxtechnologies.com (o) (925)388-0265 (c) (510)928-2683 "building energy simulations at your fingertips"
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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