Ed,
I don't understand why you have to convert from W/m2 to Wh/m2, since Watt a unit of rate, i.e., 1 joule/sec , and not cumulative ?
I still don't have a good enough sense of your problem to tell, but I can think of 3 possible areas that might cause such a problem: mismatch of the global horizontal to the solar geometry, apportioning to subhourly values, and the calculation of the direct normal from the total global horizontal solar.
If you send me your raw data file and the output from the WeatherConverter, I can take a look.
Joe
Joe Huang White Box Technologies, Inc. 346 Rheem Blvd., Suite 108D Moraga CA 94556 yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx www.whiteboxtechnologies.com (o) (925)388-0265 (c) (510)928-2683 "building energy simulations at your fingertips"
On 3/28/2013 1:53 PM, Edward G. Lyon wrote:
Thanks Linda….but when I factor W/m2 by .166667 to get Wh/m2 as input, calculation of direct normal still blows up….sometimes by a lot…
Ned Lyon, P.E. (MA, WV)
Staff ConsultantSIMPSON GUMPERTZ & HEGER
781.907.9000 main
781.907.9350 direct
781.907.9009 fax
www.sgh.com
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Linda Lawrie
Sent: Thursday, March 28, 2013 4:43 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Weather converter issues
Sorry -- sent too soon.
No key -- you use conversion units. (as designed -- no automatic try at conversion)Field: DataUnits
There should be as many DataUnits entries as DataElement entries. These are not generally used but may be used in the future for automatic conversions. The exception to this is “temperature” fields. Use “f” for Fahrenheit, “k” for Kelvin temperatures. Note that the DataConversionFactor for this field will be applied prior to conversion. (Many formats use integer numbers to represent values that are in tenths, for example.)
Field: DataConversionFactors
There should be as many DataConversionFactors entries as DataElement entries. These factors are multiplicative factors (i.e. the input value is multiplied by this factor) and can be used to process input data into the values used in the EPW weather files.
You need to supply the conversion factors. Only built in ones are described above - F or K.
At 02:35 PM 3/28/2013, Edward G. Lyon wrote:
I am trying to use the weather converter to format my site weather station data. I find the help file lacking a concise list of conversion DataUnits.
Is there a key for barometric pressure in.Hg, wind speed miles per hour, wind direction compass points (N, NE, SSW), time in a 2:10 p format?
If not I can preprocess my file…
More importantly, it seems to choke on my 10 minute data file. I set NumInHour=6, but I get following errors:
First read Hour number=0; Expected =1
First read Hour number will be used as hour=1 and reported if not same for each day read in
Warning ** Suspected missing data line after processing 1 days
Month=6 Day=9 Hour=1
Processing continues but may be in error
Warning ** DirectNormalRadiation 378.8 > max theoretical= 177.1 Wh/m² on date= 6/ 9 at hour= 5
These continue through the whole file processing, I only have global horizontal solar data for input reported as W/m², and this directnormal error seems to start at an hour crossing in the file after reading some sub hour data…Do I have to factor the input data for the shorter time step?
Ned Lyon, P.E. (MA, WV)
Staff Consultant
SIMPSON GUMPERTZ & HEGER
| Engineering of Structures and Building Enclosures
41 Seyon Street, Bldg. 1, Suite 500
Waltham, MA 02453
781.907.9000 main
781.907.9350 direct
781.907.9009 fax
www.sgh.com
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