Re: [EnergyPlus_Support] TMY3 Weather files

[Mehry Yazdanian <m_yazdanian@xxxxxxx>]

Linda,
I am aware of different units. The Direct solar matches very well, it is the diffuse. The difference I see in the diffuse solar varies between locations. For some it is about 25% difference so I don't think it is a truncation issue. What I don't understand is that even if the .bin file does include the diffuse, the weather converter somehow calculates it. Could it be a problem in the converter program?

Thanks.

On Fri, Oct 19, 2012 at 10:14 AM, Linda Lawrie <linda@xxxxxxxxxxxxxx> wrote:

 

One simple note is that the .bin files have solar radiation in IP units (BTUH) vs EPW files in Wh/m2). So there is a translation.
Plus, the .bin files have Total Solar/Global and Direct.  But no diffuse.  So, another translation.

oh, and you need to unpack the .bin to FMT which may truncate some of the values -- depending on the precision used.

Wind direction should be a direct copy unless how the original TMY3 was converted differed.

 At 11:04 AM 10/19/2012, mehry1205 wrote:

I am making some DOE2 and EnergyPlus comparison runs, I want to make sure I use the comparable set of weather files for both. Here is what I did:

1) I downloaded the TMY3 DOE2 Weather files (.BIN) from the site ( http://www.whiteboxtechnologies.com/weather_data.html)

2) I Then used EnergyPlus weather converter to get epw from the .BIN file (I first created the .fmt and then ran weather converter on the .fmt).
3) When I made the comparison runs, I see that the diffuse Horizontal solar is different between the two programs.
4) I compared the translated EPW file to the EPW file that I get from EnergyPlus Website. I see that the diffuse Horizontal solar is also different between the translated EPW and the distributed EPW.
5) I also see some differences in wind direction between the two EPW files.
I need to understand why there is a difference and how to make sure I use the comparable weather files (BIN and EPW).
Thanks

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