[Bldg-sim] Weather Station recommendations

[Joe Huang via Bldg-sim]

As the co-author of the Zhang-Huang Model, I can say that the information in your first 
sentence is garbled.  The ZHM calculates the global horizontal radiation based on various 
climatic parameters, i.e., cloud cover, temperature change over 3 hours, wind speed, etc.  
It is NOT used to derive the direct/diffuse split, so I don't understand how that has 
gotten into the EnergyPlus documentation. I have mentioned this misunderstanding to 
members of the EnergyPlus Team five years ago or so, but it seems it still persists.

A week or so ago I read that the Perez Model is used only for hourly data, which raises 
the question how the direct/diffuse split is done when there's subhourly GHI data?

Lastly, I would also add a caution that all-sky modeling, i.e., solar radiation under 
non-clear conditions, is still an evolving topic, and that just because the results didn't 
make EnergyPlus crash it doesn't necessarily mean that they're right.

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"

On 11/11/2016 12:54 PM, Lukas Hovee via Bldg-sim wrote:
> FYI -
>
> The EnergyPlus Weather File Converter packaged with the Energy Plus download includes 
> two methods for performing the direct/diffuse split: Zhang-Huang and the Perez Split.  
> See the Energy Plus Auxiliary Programs for more detail:
>
> http://bigladdersoftware.com/epx/docs/8-6/auxiliary-programs/definitions-file-custom-file-processing.html#custom-file-processing---solar-radiation-value-calculation
>
> I've recently successfully used this tool to generate an EPW given only hourly global 
> horizontal (plus the necessary non-solar measurements).  One bug I would mention - for 
> the 'Custom File Processing' option, it only seems to accept space delimited files - 
> even if you specify otherwise in the Definitions file...
>
> -  Luke
>
> --
> Lukas Hovee, P.E.
>
> *360 Analytics*
> Building Energy Analysis Consultants
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