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<DIV><SPAN class=642331919-10102002><FONT face=Arial color=#0000ff
size=2>Hello:</FONT></SPAN></DIV>
<DIV><SPAN class=642331919-10102002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=642331919-10102002><FONT face=Arial color=#0000ff size=2>Here's
my $0.05 worth.</FONT></SPAN></DIV>
<DIV><SPAN class=642331919-10102002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=642331919-10102002><FONT face=Arial color=#0000ff size=2>First,
I doubt seriously, that DOE-2 is +- 2 % accurate, compared to what? This
claim would need justifying. </FONT></SPAN></DIV>
<DIV><SPAN class=642331919-10102002><FONT face=Arial color=#0000ff size=2>One
way of testing DOE-2 in the near future is with ASHRAE new accuracy test
for air-side systems, 865-RP.</FONT></SPAN></DIV>
<DIV><SPAN class=642331919-10102002><FONT face=Arial color=#0000ff size=2>Tests
are available for 7 systems, under varying conditions. The "accuracy" of 865-RP
has been developed</FONT></SPAN></DIV>
<DIV><SPAN class=642331919-10102002><FONT face=Arial color=#0000ff size=2>to be
+- 1%, which caused the two contractors much pain, and many years of
effort.</FONT></SPAN></DIV>
<DIV><SPAN class=642331919-10102002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=642331919-10102002><FONT face=Arial color=#0000ff size=2>This
should help resolve some of the issues regarding accuracy.</FONT></SPAN></DIV>
<DIV><SPAN class=642331919-10102002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=642331919-10102002><FONT face=Arial color=#0000ff
size=2>Jeff</FONT></SPAN></DIV><BR>
<P><FONT face=Tahoma size=2>8=! 8=) :=)
8=) ;=) 8=) 8=( 8=)
8=() 8=) 8=| 8=)
:=') 8=) 8=) 8=?</FONT> </P>
<P><I><FONT face=Tahoma size=2>Jeff S. Haberl, Ph.D.,
P.E.............................jhaberl@esl.tamu.edu</FONT></I> <BR><I><FONT
face=Tahoma size=2>Associate Professor....................................Office
Ph: 979-845-6507</FONT></I> <BR><I><FONT face=Tahoma size=2>Department of
Architecture...........................Lab Ph: 979-845-6065</FONT></I>
<BR><I><FONT face=Tahoma size=2>Energy Systems
Laboratory...........................FAX: 979-862-2457</FONT></I> <BR><I><FONT
face=Tahoma size=2>Texas A&M
University..................................77843-3581</FONT></I> <BR><I><FONT
face=Tahoma size=2>College Station, Texas, USA...........................URL:
www-esl.tamu.edu</FONT></I> </P>
<P><FONT face=Tahoma size=2>8=/ 8=) :=) 8=)
;=) 8=) 8=() 8=) :=)
8=) 8=! 8=) 8=? 8=)
8=) 8=0 </FONT></P>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B> postman@gard.com
[mailto:postman@gard.com]<B>On Behalf Of </B>Steve Gates<BR><B>Sent:</B>
Thursday, October 10, 2002 12:00 PM<BR><B>To:</B>
BLDG-SIM@gard.com<BR><B>Subject:</B> [BLDG-SIM] Static Pressure Reset modeling
in DOE 2<BR><BR></FONT></DIV>
<DIV><FONT face=Arial size=2>Mark, </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>In many cases I fully agree with you about
the value of keeping the problem simple. Indeed, we have been
criticized numerous times in the past for DOE-2's 'overly simplistic'
equipment algorithms. Interestingly, when a couple of
recent independent studies compared DOE-2's chiller and cooling tower
algorithms to more sophisticated algorithms published in the literature,
they found that DOE-2's 'simple' algorithms gave the most accurate
results. (One of these studies found that the ASHRAE Toolkit chiller
algorithm is so complex that it is next to impossible to calibrate to
manufacturer's data, and generates errors on the order of +/- 10%; while
DOE-2's accuracy was on the order of +/- 2%).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>But I have to disagree with you in the case of
variable-speed fans and pumps. How many of you have heard the claim of VSD
salemen that "power goes as the cube of the flow"? That claim is
patently false when applied to airhandlers and pumps. It is only true in
the case where the pressure falls off as approximately the square of the
flow, such as in a cooling tower, or a piping system with no valves. In
the case of systems where a significant portion of the pressure loss is
associated with non-turbulent components, pressure losses do not follow
the flow-squared law. And a fixed pressure setpoint further reduces
the potential savings. In fact, if the pressure setpoint is
set high enough, the VSD will run at full speed regardless of flow (I have
observed this situation).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>So it can make sense for DDC control systems
to reset the setpoint as a function of the pressure requirement of the
worst case component (but watch out for the rogue VAV box or coil!) And,
since one of our goals is to allow engineers to utilize DOE-2 to study
the cost-effectiveness of more sophisticated control sequences, the
program needs to do a better job of simulating this situation.
Granted, we will keep the algorithms as simple as is consistent with this
goal! And the default control sequence will utilize a fixed setpoint so
everyone can keep asking "how come the power consumption doesn't drop off as
the cube of the flow, like the salesman told me?"</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=MAW@abacus-engr.com href="mailto:MAW@abacus-engr.com">Mark A.
Webb</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=steve.gates@doe2.com
href="mailto:steve.gates@doe2.com">Steve Gates</A> ; <A
title=BLDG-SIM@GARD.COM
href="mailto:BLDG-SIM@GARD.COM">BLDG-SIM@GARD.COM</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Thursday, October 10, 2002 4:11
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> RE: [BLDG-SIM] Static Pressure
Reset modeling in DOE 2</DIV>
<DIV><FONT face=Arial size=2></FONT><FONT face=Arial
size=2></FONT><BR></DIV>
<DIV><SPAN class=474480811-10102002><FONT face=Arial color=#0000ff
size=2>Has anyone ever told you guys that you were nuts! By the time
you get done with all of your guessing, manipulation, trickery, and
manual curve creation - you could have just made an intelligent guess
and been closer. With the added bonus of saving a bunch of time.
Unless it is some kind of PhD kind of thing.</FONT></SPAN></DIV>
<DIV><SPAN class=474480811-10102002><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=474480811-10102002><FONT face=Arial color=#0000ff
size=2>Mark</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr style="MARGIN-RIGHT: 0px">
<DIV></DIV>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left><FONT
face=Tahoma size=2>-----Original Message-----<BR><B>From:</B> Steve Gates
[mailto:stvgates@pacbell.net] <BR><B>Sent:</B> Wednesday, October 09, 2002
7:44 PM<BR><B>To:</B> BLDG-SIM@GARD.COM<BR><B>Subject:</B> [BLDG-SIM]
Static Pressure Reset modeling in DOE 2<BR><BR></FONT></DIV>
<DIV><FONT face=Arial size=2>Currently there is no "optimized static
pressure control" for fans/ducts in DOE-2. However, J. Hirsch &
Associates has funding to implement such a mechanism in DOE-2.2
within the next few months. The funding is provided by Southern
California Edison as part of their "Energy Design Resources" program (<A
href="http://www.energydesignresources.com/">http://www.energydesignresources.com/</A>).
These enhancement will be incorporated into both DOE-2.2 and eQUEST (not
PowerDOE), and will be made available to the user community at no
charge.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>This control mechanism will be similar to the
head reset controls already implemented for variable-flow pumping
systems in DOE-2.2, where the pump head setpoint can be reset based on the
hourly head demand of the worst-case valve. The actual pump head is then a
function of the worst-case valve head, plus the additional
variable-flow head losses of the loop piping and the central plant
equipment. This control sequence maximizes the potential
savings of variable-speed pumps, as the required speed of a pump is
dependent on both the flow as well as the head requirement; with the head
requirement usually being the dominant factor. (The maximum head of a
pump varies roughly as the square of the impeller speed; if the head
requirement does not decrease as the flow drops off, then the speed
cannot decrease significantly).</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>For fans/ducts, the simple curve-fit that
varies fan power as a function of flow will become obsolete. Instead,
DOE-2.2 will keep track of the static requirement of the worst-case
VAV box, as well as ducting, coils, filters, etc. Each component
must be accounted for separately, as the head of all of these devices
varies differently for a given flow. (Some components, such as
ducts and sound traps, experience turbulent flow, and their head varies as
the 1.85 power of flow. Other components, such as coils and filters,
are more laminar, and their head typically varies in the range of the
1.1-1.6 power of flow. Still others, such as a VAV box without
an intelligent DDC system to monitor damper position, will have a constant
head requirement; i.e. a constant head setpoint out toward the end of the
ducting.) These changes will require DOE-2.2 to know about the flow
through each component in the system, the component's head characteristic,
as well as the fan map for a given type of fan (forward-curved, airfoil,
etc.) Based on flow and static requirement, DOE-2.2 will then be
able to determine the fan speed and power consumption. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>In the meantime, you can approximate
"optimized static pressure control" by generating a new curve that causes
power to fall off more rapidly with flow than the default curves.
However, this is not a straightforward task, as you would have to
calculate by hand all of the algorithms we have designed for DOE-2,
and repeat the calculations for a series of flows. Perhaps someone
has already done this exercise, and can share their curves with
you.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Steve Gates</FONT></DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=babetsk@jbb.com
href="mailto:babetsk@jbb.com">babetsk@jbb.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=BLDG-SIM@GARD.COM
href="mailto:BLDG-SIM@GARD.COM">BLDG-SIM@GARD.COM</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, October 09, 2002
2:41 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [BLDG-SIM] Static Pressure
Reset modeling in DOE 2</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>
<DIV>To Doe 2 Users:</DIV>
<DIV> </DIV>
<DIV>Hello,</DIV>
<DIV> </DIV>
<DIV>Does anybody know if there is a way to model (in
DOE-2) an "optimized static pressure control", that is a control
method where the controller dynamically adjusts the static pressure set
point based on the position of the modulating devices in the VAV
terminal units? </DIV>
<DIV> </DIV>
<DIV>Thank you</DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial size=2>Konstantin E. Babets, Ph.D.</FONT></DIV>
<DIV><FONT face=Arial size=2>CFD/Energy Modeling Engineer</FONT></DIV>
<DIV><FONT face=Arial size=2>Jaros Baum and Bolles<BR>Consulting
Engineers<BR>80 Pine Street<BR>New York NY 1005<BR>Tel:
212.530.9455<BR>Fax: 212.269.5894<BR></FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV></FONT></DIV><PRE>==================
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