<div>Chris, Joe, others,</div><div><br></div>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. <div>
<br></div><div>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. </div>
<div><br></div><div>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. </div>
<div><br></div><div>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.</div>
<div><br></div><div>Am I alone on this or do others feel the same way?</div><div><div><br clear="all">Ralph T Muehleisen<br>PhD, PE, LEED AP, INCE Board Certified, FASA<br>Principal Building Scientist<br>Argonne National Lab<br>
9700 S. Cass Ave, Bldg 221<br>630-252-2547, <a href="mailto:rmuehleisen@anl.gov" target="_blank">rmuehleisen@anl.gov</a><br><br>
<br><br><div class="gmail_quote">On Thu, Jul 26, 2012 at 2:31 PM, Joe Huang <span dir="ltr"><<a href="mailto:yjhuang@whiteboxtechnologies.com" target="_blank">yjhuang@whiteboxtechnologies.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><u></u>
<div text="#000000" bgcolor="#ffffff">
Chris, others,<br>
<br>
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. <br>
<br>
Joe<br>
<pre cols="90">Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 108D
Moraga CA 94556
<a href="mailto:yjhuang@whiteboxtechnologies.com" target="_blank">yjhuang@whiteboxtechnologies.com</a>
<a href="http://www.whiteboxtechnologies.com" target="_blank">www.whiteboxtechnologies.com</a>
(o) <a href="tel:%28925%29388-0265" value="+19253880265" target="_blank">(925)388-0265</a>
(c) <a href="tel:%28510%29928-2683" value="+15109282683" target="_blank">(510)928-2683</a>
"building energy simulations at your fingertips"
</pre>
<br>
On 7/25/2012 10:45 AM, Joe Huang wrote:
<blockquote type="cite">Chris,
<br>
<br>
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?
<br>
<br>
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.
<br>
<br>
Joe
<br>
<br>
<br>
On 7/25/2012 9:53 AM, Chris Jones wrote:
<br>
<blockquote type="cite">Joe
<br>
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?
<br>
<br>
<br>
At 07:43 AM 25/07/2012, Joe Huang wrote:
<br>
<blockquote type="cite">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. > > >
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-- Joe Huang White Box Technologies, Inc. 346 Rheem Blvd.,
Suite 108D Moraga, CA 94556 (o) <a href="tel:%28925%29388-0265" value="+19253880265" target="_blank">(925)388-0265</a> (c)
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<br>
</blockquote>
<br>
>>
<br>
Christopher Jones, P.Eng.
<br>
Suite 1801, 1 Yonge Street
<br>
Toronto, ON M5E1W7
<br>
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<br>
<br>
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