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[EnergyPlus_Support] Re: weather file radiation
hello Ned
yeah you're right, the excel program doesn't account for cloud cover
corrections, something I'll have to figure out...seems like I could
get sky clearness factors (1-10, 10 full covered), do you think I
should aply those directly as a percentage of the global radiation(
ed. 8/10, 9/10). or should that affect only either the duffuse or
direct components?...
but .. yes.. that could still be a mere approximation as you well
point out
as for the model used itself I searched and found this url
http://www.nrel.gov/docs/legosti/old/761.pdf as referenced by the
author of the excel file.
best regards
hector huerta
edhugar@xxxxxxxxx
A00603447@xxxxxxxx
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Edward Lyon"
<eglyon@s...> wrote:
> The problem with these calculations for energy modeling is that
they give you a perfect clear day solar value for any time period
you calculate. If you had additional sky weather data for cloud
cover, you could try to apply some cloud cover corrections.
However, correcting the solar data with a cloud cover algorithm is
still not as good as measured solar data, it can be as much as 50%
off. I know these cloud algorithms have been applied to some of the
canned weather files we use that do not have direct solar
measurements, but I have not seen the source equations yet.
>
> Ned Lyon
>
> Senior Staff Engineer
> Simpson Gumpertz & Heger Inc.
>
> 41 Seyon Street
> Building #1, Suite 500
> Waltham, MA 02453
>
> Phone: 781-907-9000
> Fax: 781-907-9009
>
>
> >>> edhugar@y... 02/06/03 11:28AM >>>
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