This is extremely embarrassing. I was right originally and wrong in my correction. You should move the building location west by 7.5 degrees longitude.
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"
Correction to the last sentence of what I had written, if you're using an EPW with solar in European convention, i.e., measured around the hour, you should move the building location east by 7.5 degrees longitude, not west.
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"On 2/5/2016 3:25 PM, Joe Huang wrote:
Lukas,
I don't have an answer to your first question, but to your second question, yes, there's a difference in convention between North America and Europe in reporting solar radiation, where the US convention is for the previous time step, i.e., -1:00 to 0:00 hour, while the European convention is around the time step, i.e., -0:30 to +0:30.
If you're feeding the WeatherConverter both GHI and DNI, then this difference in convention is immaterial. However, if you're relying on the WeatherConverter to calculate the DNI from GHI, then you should use the TimeHourOffset, although I'm not sure how that value is defined. From what I know, I would have thought that for the NA convention it would be -0.5, and the European convention 0.0. In either case, though, there will still be a mismatch between the EPW and EnergyPlus when doing the calculation, unless EnergyPlus also knows to adjust accordingly. If EP doesn't, you can always account for it by moving the building location west by 7.5 degrees longitude.
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"Hi,
I'm working on a web tool that creates free weather files for energy and hygrothermal simulations from gridded mesoscale datasets for a any location for North Europe Shiny weather data
The tool creates .def and .cst files from which the user can create .epw files with the Energyplus 8.4 weather converter tool. This works fine as long as the data is not longer than 8760 rows. But the weather converter tool crashes when the .cst file consist of more rows than 8760. Is there something I'm missing here or can't the tool create multi year files?
Another thing about the weather converter tool is that it seems to be a half an hour off when calculating the solar elevation used for solar radiation data. Seems like it calculates the sun's elevation at full hours (but this should be calculated e.g. at 12:30 for the 13:00 timestamp)
Lukas Lundström
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Posted by: Joe Huang <yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx>
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