Re: [EnergyPlus_Support] Re: Problem with ISHRAE weather data

["Joe Huang" <yjhuang@xxxxxxx>]

Paul,

Curiousity made me compare the EPW stats of  a couple of Indian locations 
wtih both ISHRAE and IWEC weather files (Nagpur, New Delhi). You're right, 
there's something wrong with the solar on the ISHRAE weather files. They're 
much too high (at least 4X or even more on maximum direct normal solar). 
Funny though, that the global average sola on the two kinds of files are in 
the same ballpark (low numbers). At first, I wondered if there was a unit 
conversion mistake, but then the only other SI unit for energy would be 
calories, which would result in a smaller, not bigger, number (1 calorie = 
4.18 joule).  Something's defintely amiss, though.  This will p robably 
require tracing the data back to the original ISHRAE files.

Joe

----- Original Message ----- 
From: "Paul Reeves" <paulreeves5@xxxxxxxxx>
To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Monday, January 30, 2006 7:48 PM
Subject: [EnergyPlus_Support] Re: Problem with ISHRAE weather data


> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Linda Lawrie <linda@l...>
> wrote:
>>
>> We have not heard this about ISHRAE weather data.
>>
>> How did you determine they are 3X larger than possible?  (i.e.,
> what
>> are you using to determine "max possible"?)
>>
>>
>> Linda
>>
>
> Linda,
>
> I arrived at the "3X larger than possible" observation based on the
> assumption that the solar data is for planet Earth and that we still
> have some atmosphere.
>
> Sorry, I couldn't resist that one.  But really, if you look at any of
> the ISHRAE data sets (or at least most), you'll notice that the ET
> direct normal solar radiation is on the order of 5000 Wh/m2 whenever
> the sun is "up".  The terrestrial direct normal solar radiation
> values are often above 3000 Wh/m2, or appoximately 3 times what is
> possible here.
>
> To be honest, I haven't used the EPW data sets very much, so I might
> be missing something, but all the other data sets I've looked at make
> sense.
>
> Paul
>
>
>
>
>
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> 



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