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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>A few other comments regarding calibration…<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Calibrating to annual utility use is
better than nothing, but still not worth much. Calibrating to monthly utility
bills can be pretty good, but that is very dependent upon your goals.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>First, note that DOE-2 and derivatives are
(still, I believe) hourly simulations. (EnergyPlus can use shorter time
steps.) Utilities usually bill demand based on a 15-minute period, or less
commonly on a 30-minute period. Perhaps some bill on an hourly period, but I
haven’t run into that. Depending upon when the peak demand occurs, and
what is causing it, the 15-minute and hourly peak demands can be VERY
different.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Second, it is next-to-impossible to truly
calibrate a building in the absence of zonal energy use information. VAV box
operation and reheat can be particularly problematic, but there are many other
areas of concern. Building simulation programs generally assume proper or at
least decent operation. However, this is seldom the case: economizers don’t
work properly, setpoints are suboptimal, there is simultaneous heating and
cooling due to leaking valves or other problems, etc.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>A calibrated model MAY improve savings
estimates for many retrofits, but again, it depends upon whether the retrofit
will be impacted by such problems. One example is a conversion of a system
from constant flow to variable flow. First, most simulations don’t do a
great job of simulating variable speed pumping or VAV fan operation, although
this is improving. Second, most variable flow systems don’t operate
optimally, and proper operation is what we typically assume in simulation.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>(For documentation of some of the issues
with simulating variable flow systems, refer to the dictionary for DOE2.2R at <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><a
href="http://doe2.com/download/DOE-22/DOE22Vol2r-DictionaryRefrigeration.pdf">http://doe2.com/download/DOE-22/DOE22Vol2r-DictionaryRefrigeration.pdf</a><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>It states, in part, that <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>“Pressure is not considered in the
air-side calculations. VAV fan power is modeled using a simple curve without
considering where the pressure drops exist in the system, where the static
pressure sensor is located, or what the static setpoint is.”)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Put another way, it is pretty easy to simulate
a constant flow system, and the energy use for that system, since it is
relatively unlikely that the system won’t be operating as expected.
However, a variable flow system is likely to not be operating as expected, is
not particularly well-modeled by DOE-2, and hence the savings estimates from
even a calibrated simulation might not be very good.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>This is not to discourage you from
calibration—far from it. Your model will certainly be better after
calibration, and you will learn a ton in the process. However, I encourage you
to note the previous resources and comments. It certainly is VERY “easy
to underestimate the actual time commitment required:” In the early
1990s I performed multiple research-level calibrations. For one large
building, I calibrated a DOE-2 model to hourly end-use AND zonal subsystem data
as part of a research project. The process was months, not days. That was a
very detailed calibration, but it demonstrated how a model calibrated to
monthly data can still be far from reality.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p><font size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>William
E. Koran, P.E.</span></font> <br>
<font size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>Senior
Engineer</span></font> <br>
<font face=Tahoma><span style='font-family:Tahoma'>Q u E S T</span></font> <br>
<font size=1 face=Tahoma><span style='font-size:7.5pt;font-family:Tahoma'>Quantum
Energy Services and Technologies</span></font> <br>
<font size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>Voice:
503-557-7828</span></font> <br>
<font size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>Fax:
510-540-7268</span></font> <br>
<font size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>Web:</span></font>
<a href="http://www.quest-world.com" title="http://www.quest-world.com"><font
size=2 face=Tahoma title="http://www.quest-world.com"><span style='font-size:
10.0pt;font-family:Tahoma'>www.quest-world.com</span></font></a> <o:p></o:p></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Brandon Nichols<br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, August 27, 2008
3:17 PM<br>
<b><span style='font-weight:bold'>To:</span></b> Chris Mullinax;
bldg-sim@lists.onebuilding.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [Bldg-sim] Simulation
Calibration</span></font><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'><o:p></o:p></span></font></p>
</div>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:blue'>Check out "Computerized Building
Energy Simulation Handbook" by James Waltz... there's a
click-through to Amazon.com on <a
href="http://elcca-exchange.blogspot.com/">my blog</a> for this
fundamental energy modeler's reference manual. An entire chapter is
devoted to model calibration. In addition, there are numerous
quantitative and anecdotal tips for improving the quality of and reducing the
time required to build energy models.</span></font><font size=3
face="Times New Roman"><span style='font-size:12.0pt;font-family:"Times New Roman"'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt;font-family:"Times New Roman"'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:blue'>For an example related to model
calibration, you may find that only a few or perhaps no data loggers are
required -- setting up trend logs, taking instantaneous branch circuit amperage
readings (for relatively constant load circuits such as lighting) and
accessing existing building schedule information resident in a modern EMCS may
be sufficient. </span></font><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt;font-family:"Times New Roman"'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:blue'>The goal, as Chris stated, is for your
model to be within ± 5% of actual energy consumption as documented by the
utility bills, month-to-month. Chris is also spot-on about the iterative
nature of the process... it's easy to underestimate the actual time commitment
required.</span></font><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt;font-family:"Times New Roman"'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=blue face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:blue'>Brandon Nichols, PE, LEED AP<br>
Mechanical<br>
HARGIS ENGINEERS<br>
<st1:Street w:st="on"><st1:address w:st="on">600 Stewart St</st1:address></st1:Street><br>
<st1:address w:st="on"><st1:Street w:st="on">Suite</st1:Street> 1000</st1:address><br>
<st1:place w:st="on"><st1:City w:st="on">Seattle</st1:City>, <st1:State w:st="on">WA</st1:State>
<st1:PostalCode w:st="on">98101</st1:PostalCode></st1:place><br>
d | 206.436.0400 c | 206.228.8707<br>
o | 206.448.3376 f | 206.448.4450<br>
<a href="http://www.hargis.biz">www.hargis.biz</a></span></font><font size=3
face="Times New Roman"><span style='font-size:12.0pt;font-family:"Times New Roman"'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt;font-family:"Times New Roman"'><o:p> </o:p></span></font></p>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt;font-family:"Times New Roman"'>
<hr size=2 width="100%" align=center tabIndex=-1>
</span></font></div>
<p class=MsoNormal style='margin-bottom:12.0pt'><b><font size=2 face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma;font-weight:bold'>From:</span></font></b><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>Chris Mullinax<br>
<b><span style='font-weight:bold'>Sent:</span></b> Wednesday, August 27, 2008
1:26 PM<br>
<b><span style='font-weight:bold'>To:</span></b> bldg-sim@lists.onebuilding.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> [Bldg-sim] Simulation
Calibration</span></font><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'>I
have used equest a number of times to show clients the relative effects of
changing from standard efficiency to higher efficiency equipment or say from T8
to T5 lighting systems. Generally, pretty basic models. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'>I
now have a client a (a municipality) that is interested in
“calibrating” the models to get more precise information. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'>I’ve
heard the term “calibration” as it relates to models, and I think I
understand the concept, but how is this actually done? Is it just a
matter of improving the details of the model, or is there testing of walls and
other systems to determine actual installed values?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'>Are
there any good articles out there on this topic?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'>All
help appreciated.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Thanks,</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Chris Mullinax, P.E. <font color="#00b050"><span
style='color:#00B050'>LEED AP</span></font></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>pn: 770-387-1334</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>fx: 770-387-1383</span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><a href="mailto:chris@mullinaxsolutions.com">chris@mullinaxsolutions.com</a></span></font><o:p></o:p></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><a
href="http://www.mullinaxsolutions.com">www.mullinaxsolutions.com</a><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
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