[Equest-users] Temperature in weather data

[Ralph Muehleisen]

Chris, Joe, others,

The dramatic effects of simply rounding off/ceiling the temperature data in
weather files is a perfect example of why we need to, as an industry, move
from deterministic energy predictions to stochastic energy predictions.

Weather and occupancy are inherently stochastic and when we couple
that stochasticity with our uncertainty in so many of the actual building
parameters (at least uncertainty as to their what their values will be when
installed), it seems to me that far more meaningful energy predictions
could be made using stochastic methods.

While you wouldn't necessarily want to use stochastic methods during much
of the design iteration, stochastic estimation should be a standard
procedure for comparing major iterations and for final energy predictions.

For all us researchers, there is plenty of work to be done in properly
quantifying the stochasticity of weather, occupancy and other stochastic
parameters and in developing uncertainty profiles for important parameters
that are not stochastic.  There is also opportunities for industry to
develop the wrappers to take the info and create the DOE2 wrappers.

Am I alone on this or do others feel the same way?

Ralph T Muehleisen
PhD, PE, LEED AP, INCE Board Certified, FASA
Principal Building Scientist
Argonne National Lab
9700 S. Cass Ave, Bldg 221
630-252-2547, rmuehleisen at anl.gov



On Thu, Jul 26, 2012 at 2:31 PM, Joe Huang <yjhuang at whiteboxtechnologies.com
> wrote:

> **
> Chris, others,
>
> Since as you've raised the question of how significant would be adding
> extra precision to the weather data in DOE-2, I was sent a copy of a recent
> paper by Annie-Claude Lachapelle of the Univ. of Calgary given at eSim
> Canada 2012 on this exact topic, "DOE2 Dry-Bulb Temperature Precision Level
> Impact on Sensible Economizer Performance".   With the author's permission,
> I've attached the paper with this post.
>
> Joe
>
> Joe Huang
> White Box Technologies, Inc.
> 346 Rheem Blvd., Suite 108D
> Moraga CA 94556yjhuang at whiteboxtechnologies.comwww.whiteboxtechnologies.com
> (o) (925)388-0265
> (c) (510)928-2683
> "building energy simulations at your fingertips"
>
>
> On 7/25/2012 10:45 AM, Joe Huang wrote:
>
> Chris,
>
> My attention on this issue was first raised about 15 years ago when I was
> working with non-US weather data , i.e., the rest of the world, that are
> all reported in 0.1 C. I've noticed since that US stations have also moved
> to the use of metric units, i.e., 0.1 C for temperature. The DOE-2 weather
> format is still in integer F, which leads to three unfortunate effects: (a)
> hourly records can be off by as much as 0.5 F, (b) clumping of the
> temperature distribution, and (c) statistics such as degree-days will be
> off by a percent or two compared to the original data. Now, one can say
> that all this is immaterial in the bigger picture of things, which has been
> the default attitude so far, but since it's really quite simple to fix, why
> not get it right, i.e., doesn't it feel much better to see the same
> temperatures in the DOE-2 outputs as in the original weather data?
>
> BTW, all the weather data that I've looked at are records of conditions on
> the hour, not the average over the hour, except for solar radiation.
>
> Joe
>
>
> On 7/25/2012 9:53 AM, Chris Jones wrote:
>
> Joe
> Given that the time steps are an hour, and the fact that weather data is
> averaged over an hour, plus the fact that the building local will have
> variations from the weather station local, would an extra decimal point
> provide more useful information?
>
>
> At 07:43 AM 25/07/2012, Joe Huang wrote:
>
> This is not possible at present without changing the DOE-2.2 source code
> to read a weather input file with decimal values. When DOE-2 was first
> designed in the early 1980's, memory was a big concern, so the weather data
> was reduced to integers and then packed, which is why the DOE-2 *.BIN file
> is so small (146K). I have actually developed a modified file format for
> *.BIN where I save an extra digit of precision, i.e., temperatures to 0.1F
> instead of 1 F, but the source code would also need to be changed slightly
> to read this extra information. I've mentioned this to the developer of
> eQUEST/DOE-2.2 and will be experimenting with making this change to the
> source code. If and when it's proven to work and gets incorporated into
> DOE-2.2, I'll let everyone know. I welcome anyone who thinks this is a
> useful modification to send me an e-mail. It might spur me on to do
> something! Joe On 7/23/2012 2:44 AM, è”¡æ˜€èŠ wrote: > Hi, everyone: > > We
> know that eQUEST can edit personal weather data. > But the dry-bulb and
> wet-bulb temperature in weather data can only > enter integers. > Is it
> possible to have more precise temperature to decimal place? > Thank you
> very much. > > > _______________________________________________ >
> Equest-users mailing list >
> http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org >
> To unsubscribe from this mailing list send a blank message to >
> EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG > -- Joe Huang White Box
> Technologies, Inc. 346 Rheem Blvd., Suite 108D Moraga, CA 94556 (o)
> (925)388-0265 (c) (510)928-2683 www.whiteboxtechnologies.com "Building
> energy simulations at your fingertips"
> _______________________________________________ Equest-users mailing list
> http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org To
> unsubscribe from this mailing list send a blank message to
> EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG </x-flowed>
>
>
> >>
> Christopher Jones, P.Eng.
> Suite 1801, 1 Yonge Street
> Toronto, ON M5E1W7
> Tel. 416-203-7465
> Fax. 416-946-1005
> email cj at enersave.ca
>
>
>
>
>
> _______________________________________________
> Equest-users mailing listhttp://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
> To unsubscribe from this mailing list send  a blank message to EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG
>
>
> _______________________________________________
> Equest-users mailing list
> http://lists.onebuilding.org/listinfo.cgi/equest-users-onebuilding.org
> To unsubscribe from this mailing list send  a blank message to
> EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120727/6b5b3d81/attachment-0001.htm>