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

Arunabha Sau runabha at gmail.com
Tue Feb 11 20:58:19 PST 2014


Splendid work, Joe.
Thank you. Definitely I would like to have the contact for the ISHRAE
person to get the current "typical year" weather files. Please inbox me his
contact id. I appreciate your help, deeply.

Now, taking the role of David explaining the "pre-RCx" in layman's way here
is my weak-sauce reply. For this heritage building project, on the initial
site visit we realized that the building lacks fresh air. It was one of the
major EEMs, we figured. The building was almost 100 years old, made by the
British when they ruled India. So we decided to bring the air-side
economizer into the play. Before we suggest them EEMs including an
economizer in this hot humid climate, hence to check the predicted savings,
we did make "pre-RCx" simulation model considering the sensibility of the
heritage building and its energy consuming components. So, we can establish
our Cx agenda and tune up the savings more accurately.
Did it justify your *getting prepared* analogy defining the "pre-RCx"? :)
I guess making simulation model beforehand a Cx, RetroCx, Continuous Cx or
Persistent Cx are NOT yet become mainstream practice and  is still a matter
of justification calculation of your billable hours and so on, in the US
(at least within the firms I've worked with)! That said, fewer people use
this; I believe and guess, there is nothing wrong to name a practice since
the HVAC industry is "full" of acronyms and pseudo-acronyms (i.e. VRF &
VRV)!

No pun intended, David, maybe we should patent this intellectual property
"p-RCx" before anybody does it, right? :)


*~~~*
*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



On Wed, Feb 12, 2014 at 9:42 AM, Joe Huang <yjhuang at whiteboxtechnologies.com
> wrote:

>  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
>
>  *~~~*
> *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
>
>
>
> On Wed, Feb 12, 2014 at 7:57 AM, David Eldridge <
> 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]
>> *Sent:* Tuesday, February 11, 2014 2:43 PM
>> *To:* Arunabha Sau; David Eldridge; 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
>> 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 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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