Lukas,
While I'm glad you agree that moving the longitude is a simpler and better way to use European convention solar data in EnergyPlus, I think you should move the location westward, not eastward. I heartily admit that it gets very confusing when you think about it, as shown by my going back-and-forth yesterday on the direction. The best thing I've found to do in such cases is to do an example:
1. let's say it's 6 am, so by European convention solar is from 5:30 - 6:30 am, and the average sun position is also at 6:00 am.
2. EnergyPlus, however, uses North American convention with solar over the past hour, i.e., from 5:00 - 6:00 am,
so it calculates the sun position at 5:30 am ("TimeHourOffset" = -0.50)
3. 6 am at the true location is the same time as 5:30 am at a fictitious location 7.5 degrees west.
Does that make sense? I reserve the right to be confused :-) :-)
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"
To clarify: if you have solar data in the -0:30-0:30 convention you should move the location 7.5 degrees eastward, if you intend using the data in Energyplus. E.g. if your buildings actual location is on the longitude 15 degrees (central Europe) you add 7.5 so that the new longitude parameter (accounting for the time shifting) is 22.5. I tested it with the hyrgothermal simulation tool WUFI which expects solar data in same convention as Energyplus (-1:00-0:00) and has a nice solar radiation rose visualisation.
Regards,LukasJoe,
You have an point in that manipulating the longitude is favourable compared to manipulating the data itself. In that way as much information as possible is preserved of the original solar data. I'll start shifting longitude instead of interpolating. And add something like TimeHourOffset=0 or RealLongitude=xx.xx to the epw file's comment field.
Regards,
Lukas
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Posted by: Joe Huang <yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx>
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