[Equest-users] Fwd: Composition of weather file data

[Joe Huang]

Aru,

Your multiple mention of the EPW Indian weather files all being from 
1990 finally stirred me to do some digging, since I've been providing 
technical
assistance to ISHRAE since 2007, first in improving the solar on the 
first set of files for 58 Indian locations developed by ISHRAE , and 
then in creating a totally new second set of files for 38 locations 
completed in 2011.

I have checked the first set of ISHRAE weather files for 58 locations in 
India (these are the ones provided by ISHRAE to DOE to put on the 
EnergyPlus Weather web site as EPWs), and yes those all say 1990s for 
all months.  However, the documentation dated Sept. 1998 states that the 
raw data  contain from 5 to 10 years of historical data.  So, it may 
very well be that these files may actually contain months from different 
years, but I can't vouch for that since that was done before my involvement.

I do have a good memory on the second set of weather files, since I was 
involved in their creation.  Those are definitely  "typical year" files 
created from 15 years of data when available, but in a few cases I 
settled for as few as 3 due to data scarcity. The key point in the 
second set is that I calculated the solar radiation against 
satellite-derived solar values that just became available in 2010.  The 
final files were provided to ISHRAE in early 2011, but I have no 
information on their distribution or availability, which is completely 
in their hands.  If you're interested, I can provide you with a contact 
person at ISHRAE.

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 108D
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
http://www.whiteboxtechnologies.com
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"


On 2/11/2014 6:42 PM, Arunabha Sau wrote:
> Yea, David. Joe is just making the state-of-art weather files thru' 
> ASHRAE research projects but he is not performing any "p-RCx"!! :)
>
> Thanks David. Appreciate the reply.The EPW Indian weather files 
> typically from 1990s. It's typical year weather file. But I don't 
> think I should use this old weather file in Cx model. My project is a 
> fairly simple model with few simple EEMs - efficient chiller and air 
> side economizer.
> Of course I can calibrate the model to the current energy usage. Do 
> you think using the 1990 weather file would be good way?
>
> Cheers!
> 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
>
>
>
>
> On Wed, Feb 12, 2014 at 7:57 AM, David Eldridge 
> <DEldridge at grummanbutkus.com <mailto:DEldridge at grummanbutkus.com>> wrote:
>
>     Joe, you aren't performing "p-RCx energy models" very often?
>
>     But seriously Arunabha, the magnitude of RCx savings for a
>     facility may not be a high percentage of the total usage --
>     although the measures are low-cost and quick payback -- energy
>     modeling used as part of RCx should try to use actual weather data
>     if possible or else the variances due to weather might be the same
>     magnitude as the RCMs if you are attempting any significant level
>     of calibration for the model.
>
>     However you should then run the proposed case with typical weather
>     in order to model an "expected" annual savings.
>
>     Depending what measures you are modeling and whether you have any
>     calibration data during the "p-RCx" phase, typical weather could
>     work well enough, at least to get started and see if you should
>     continue using the model for this purpose.
>
>     David
>
>     __
>
>     David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
>
>     *Grumman/Butkus Associates*
>
>     __
>
>     *From:*Joe Huang [mailto:yjhuang at whiteboxtechnologies.com
>     <mailto:yjhuang at whiteboxtechnologies.com>]
>     *Sent:* Tuesday, February 11, 2014 2:43 PM
>     *To:* Arunabha Sau; David Eldridge;
>     equest-users at lists.onebuilding.org
>     <mailto:equest-users at lists.onebuilding.org>
>     *Subject:* Re: Fwd: Composition of weather file data
>
>     It's inevitable that the peak conditions will fluctuate from year
>     to year, that's just the chaotic nature of the weather. If you
>     use a "typical year" weather file, you will tend to get, but not
>     necessarily, an average annual peak, since the months have been
>     selected to best match the long-term distribution of temperatures,
>     humidity, solar, wind speed, etc.
>
>     What is pre-RCx ?  "pre retro-commissioning"? What is that?  Too
>     many adjectives for me :-)
>
>     In any case, if you're modeling an existing building to assess its
>     historical performance, I would definitely use actual year weather
>     files.
>     As for where to find such data, there's a proliferation of sources
>     on the Web, although most would require processing to turn them
>     into formats required by simulation programs such as eQUEST, etc.
>
>     Joe
>     Joe Huang
>     White Box Technologies, Inc.
>     346 Rheem Blvd., Suite 108D
>     Moraga CA 94556
>     yjhuang at whiteboxtechnologies.com
>     <mailto:yjhuang at whiteboxtechnologies.com>
>     http://weather.whiteboxtechnologies.com for simulation-ready
>     weather data
>     http://www.whiteboxtechnologies.com
>     (o) (925)388-0265 <tel:%28925%29388-0265>
>     (c) (510)928-2683 <tel:%28510%29928-2683>
>     "building energy simulations at your fingertips"
>
>
>     On 2/11/2014 4:09 AM, Arunabha Sau wrote:
>
>         Thanks Joe & David.
>
>         Appreciate your explanation. It was very through.
>
>         In an EPW file, I saw only 1990's data, so I was worried about
>         the peak if the typical years's data would be different or so!
>         I was modeling for pre-RCx. So, I was more concerned about
>         actual (or near to actual) heating/cooling load.
>
>         For Cx modeling, do you guys make model out of these weather
>         file or make a more customized weather file from some online
>         available weather file source or buy one?
>
>         Best regards,
>
>         Aru
>
>         /~~~/
>
>         /Texas Aggie '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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