[Equest-users] Composition of weather file data

[Joe Huang]

There are basically two types of weather files -  "typical year" or  
actual year.  An actual year weather file is simply the weather data for 
that year of record. A "typical year" is typically composed of months 
from different years selected as the most typical or representative for 
that month.  "Typical year" weather files should be created from at 
least 8 years of data on up to 30 years. People used to regard longer 
periods of record as more desirable, but this may not always be true 
taking into account regional or global climate change.

There is plenty of documentation on the creation of "typical year" 
weather file sets, such as the TMYX files developed by NREL, IWECX files 
by ASHRAE, etc., that can be found on the Web. There's no right or wrong 
about whether a "typical year" or actual year file is more proper.  
"Typical year" files are generally used when you don't know the actual 
year, like for a compliance calculation for building energy standards or 
a building yet to be built.  Actual year files should be used if the 
intent is to compare the simulation to actual building energy use data.

Expanding on what David said below, *.BIN weather files used by 
eQUEST/DOE-2 do not identify the year on each line of data. If the EPW 
file you're looking at shows only 1990,  it could be EITHER a historical 
year file from 1990 OR a "typical year" file converted from an original 
*.BIN file.

Joe


On 2/8/2014 7:17 AM, David Eldridge wrote:
> These are two separate issues:
>
> 1) what is the format of the columns for use by the program - EPW file 
> type defines this as a text file that EnergyPlus can import, eQUEST 
> uses a binary file, NREL TMY2 uses text, etc. Certain headers or data 
> fields might or might not be included in different file types.
>
> 2) how the data was chosen to be included - this selection depends on 
> the algorithm such as using typical meteorological year, actual data 
> from one continuous period, etc.
>
> Hopefully the file name might include a description of #2 - what's 
> included, while the file extension *.epw, *.bin, *.TMY will tell you 
> what format it is.
>
> You might need the context of where the file came from to verify #2 if 
> the file name itself isn't descriptive.
>
> DSE Mobile
>
> On Feb 8, 2014, at 7:14 AM, "Arunabha Sau" <runabha at gmail.com 
> <mailto:runabha at gmail.com>> wrote:
>
>> Howdy!
>>
>> Recently I happen to compare two EPW weather files - one from USA and 
>> another from India.
>> In the Indian weather file, they have only included the readings for 
>> only the year 1990 where as in the weather file from San Francisco 
>> has multiple years' entry.
>> I am very confused and wondering if in India, people do use the 
>> proper weather files!!? Can I ask you guys' insight on this, please? 
>> What is the norms and regulations for making the weather files? Does 
>> it have to have 15 or 20 years of weather data in an weather file?
>>
>> Thanks!
>> Aru
>>
>> /~~~/
>> /TexasAggie '10/
>> /JU, Kolkata '05/
>> /~~~/
>>
>> ****
>>
>> /Try not to become a man of success, but rather try to become a man 
>> of value./**
>>
>> - Albert Einstein
>>
>>
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