I'm not sure what OpenStudio does differently when reading a typical vs actual year, but my guess is that it is driven by using standard date/time functions and wanting to validate the dates in the epw. For a typical year file, the software has to ignore the years in the time stamps, because they bounce around from month-to-month. But for an actual year, it should be safe to assume that the years are meaningful, so it's not unreasonable to expect that an actual year file will have a start day that is consistent with the day/month/year in the first hour of data. But given the Sunday default, the referenced test isn't adequate to make a judgement on the type of weather file.
OpenStudio support is handled on unmethours.com, but this is probably a topic better discussed directly with one of the developers. I will forward this to the OS team.
Mike
(I've heard there's an Open Studio bulletin board, but since I don't know where it is, and maybe other EnergyPlus-related software might be doing the same thing, I thought I would just post this comment here)I've just been told by a client that Open Studio checks the DayofWeek for the start date on the EPW to the DayofWeek calculated from the date itself to determine whether the weather file is of a historical year or a "typical year" (see here) and thus would I mind changing that parameter on my EPWs which right now always sets the start date as a Sunday (I think it's hardwired in the WeatherConverter since I don't see anything in the DEF that allows that to be changed).
I find this request more than a little bizarre, because (1) whether a file is run as a "real year"or a "typical year" is a simulation option and NOT a condition of the weather file! (2) even if we accept this logic of comparing the start date DayofWeek to what it is actually to tell whether the file is a historical file or a "typical year" file, this seems like a very convoluted and error-prone way since someone (me ?) would have to calculate or look up on the Web the actual day of week for Jan 1 of that weather file, put that into the EPW, just so EnergyPlus will know "aha, this is a historical year weather file!".
This step is also completely unnecessary because EnergyPlus (as well as any other decent simulation program) has a Julian Calendar in its code to determine the day of week for any day, so why do we have to input that manually once again just to "prove" that this is a historical year run?
Let's see how another program (DOE-2) addresses this problem, which I never thought was a problem until now... In DOE-2, one enters the RUN-PERIOD is its entirety, i.e., Jan 1, 1999 through Dec. 31, 1999. If it's a "typical year" weather file that you want to start on a Sunday, then you pick a year where that happens - problem solved, no need to modify the weather file, of all things.
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"
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Posted by: Michael J Witte <mjwitte@xxxxxxxx>
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