Ned,
Your mention of "odd calculations around dawn and sunset at
times" may be related to my observation in 2013 that the sun
position calculated by the WeatherConverter was off an hour
compared to another source (see plots from Nov 13 2013 e-mail sent
to the EnergyPlus Team. Base data was ASHRAE IWEC weather file for
London, WC2 is recalculated Dir Nor using the same Global
Horizontal. Notice that the source GHI and DNI are symetrical,
while the WC2 DNI is not and more spiky.
If the sun position is inconsistent with the recorded data, you will tend to see spikes at sunrise and sunset hours, as the model tries to adjust for an abnormally high or low amount of solar for the amount of time the sun is above the horizon at those hours.
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 (o) (925)388-0265 (c) (510)928-2683 "building energy simulations at your fingertips"
Read the documentation about defining a custom input file. You can read a text file using a definition array and the converter will do a split using whatever additional information you give it. Note that you should review the file generated. I have had some odd calculations around dawn and sunset at times, but then I worked with sub hourly data as well. Pasting into an existing .epw file format will not give you the conversions.
Ned Lyon, P.E. (MA, WV)
Staff ConsultantSIMPSON GUMPERTZ & HEGER
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Send FilesFrom: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
Sent: Wednesday, November 02, 2016 10:58 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Perez direct/diffuse spliting model
Thank you Linda for the repply. I used the Weather Converter utility. Actually I modified an existing epw file by inserting my own values for global radiation and inserted zero values for the direct/diffuse components. When I converted the file I found out that energyPlus replaced the zero values with the value 999. Any help with this?
Regards,
Kostas
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Posted by: Joe Huang <yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx>
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