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<DIV><SPAN class=591544819-05062009><FONT face=Univers color=#0000ff
size=2>David,</FONT></SPAN></DIV>
<DIV><SPAN class=591544819-05062009><FONT face=Univers color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=591544819-05062009><FONT face=Univers color=#0000ff
size=2>Thanks for your suggestions. We are planning to submit a CIR and
also raise this issue with the 90.1 committee as Bill suggested. I thought
about using the same COP / same conditions in both models to demonstrate a
more realistic comparison. One approach would be to adjust my own chiller
COP to match the operating conditions of App G. However, there may be
potential hiccups in eQuest if the software is smart enough to realize it cannot
generate the ECWT specified by App G using the actual weather data. So the
other approach is to use the actual operating conditions in both models, but to
adjust the reference building COP.</FONT></SPAN></DIV>
<DIV><SPAN class=591544819-05062009><FONT face=Univers color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=591544819-05062009><FONT face=Univers color=#0000ff
size=2>Luka</FONT></SPAN></DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <B>On Behalf Of </B>David S
Eldridge<BR><B>Sent:</B> Friday, June 05, 2009 3:48 PM<BR><B>To:</B>
bldg-sim@lists.onebuilding.org;
bldg-rate@lists.onebuilding.org<BR><B>Subject:</B> Re: [Bldg-sim] Modeling
chillers at non-standard operating conditions as per Appendix
G<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=Section1>
<P class=MsoNormal><SPAN style="COLOR: black">I think your (pretty strong)
argument is that your Appendix G cooling tower will have difficulty producing
85F ECWT if the wetbulb is 86F. Your design is 9F difference, there must
be some acceptable value between -1F and 10F for the baseline building
approach.<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black">I speculate that the wording of
G3.1.3.11 was to make the baseline use a colder ECWT below 85F as standard where
available, not to penalize hot-humid projects.<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black">You may want to submit a CIR to
establish a reasonable ECWT schedule, and/or review the 90.1 addenda so that you
can move forward.<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black">Given that we can establish that
both proposed and baseline chillers operate outside of non-standard conditions
in Table 6.8.1J regarding the efficiency of the chiller, in most cases where
something is excluded from the standard the approach is to use the same value in
both models – so not penalizing you, but not a place for efficiency gains
either. This may be the approach rather than your extrapolated efficiency
– it is either covered by the standard, or not covered, so the same performance
curves could be used in both models.<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black">Unfortunate that this would be
such a potentially large energy end-use. Still there might be
opportunities since that would only apply to the mandatory efficiency of the
chiller at the non-standard conditions. The number of chillers, heat
exchanger pressure drop/pumping power, water temperatures and temperature reset
schedules could all vary – focus in these areas for efficiency opportunities in
your proposed design.<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black">I hope this helps, and please
others chime in if you agree or disagree with this
approach.<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black">David<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: black; FONT-FAMILY: 'Tahoma','sans-serif'">____________________________________________________________________________________________________________________<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: black; FONT-FAMILY: 'Calibri','sans-serif'"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 10pt; COLOR: gray; FONT-FAMILY: 'Tahoma','sans-serif'">David
Eldridge, PE<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 10pt; COLOR: gray; FONT-FAMILY: 'Tahoma','sans-serif'">LEED®
AP, HBDP<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 11pt; COLOR: black; FONT-FAMILY: 'Tahoma','sans-serif'"><BR></SPAN><B><SPAN
style="FONT-SIZE: 10pt; COLOR: #365f91; FONT-FAMILY: 'Tahoma','sans-serif'">Grumman/Butkus
Associates</SPAN></B><SPAN
style="FONT-SIZE: 10pt; COLOR: gray; FONT-FAMILY: 'Tahoma','sans-serif'"> |
</SPAN><SPAN
style="FONT-SIZE: 10pt; COLOR: #8db3e2; FONT-FAMILY: 'Tahoma','sans-serif'">820
Davis Street, STE 300 | Evanston, IL 60201 | Ph: (847) 328-3555, ext 224 | Fax:
(847) 328-4550</SPAN><SPAN
style="FONT-SIZE: 10pt; COLOR: gray; FONT-FAMILY: 'Tahoma','sans-serif'"><o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 10pt; COLOR: gray; FONT-FAMILY: 'Tahoma','sans-serif'"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 10pt; COLOR: gray; FONT-FAMILY: 'Tahoma','sans-serif'">Energy
Consultants and Design Engineers</SPAN><SPAN
style="FONT-SIZE: 11pt; COLOR: black; FONT-FAMILY: 'Calibri','sans-serif'"><BR></SPAN><SPAN
style="FONT-SIZE: 11pt; COLOR: black; FONT-FAMILY: 'Tahoma','sans-serif'">____________________________________________________________________________________________________________________<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN style="COLOR: black"><o:p> </o:p></SPAN></P>
<DIV
style="BORDER-RIGHT: medium none; PADDING-RIGHT: 0in; BORDER-TOP: medium none; PADDING-LEFT: 4pt; PADDING-BOTTOM: 0in; BORDER-LEFT: blue 1.5pt solid; PADDING-TOP: 0in; BORDER-BOTTOM: medium none">
<DIV>
<DIV
style="BORDER-RIGHT: medium none; PADDING-RIGHT: 0in; BORDER-TOP: #b5c4df 1pt solid; PADDING-LEFT: 0in; PADDING-BOTTOM: 0in; BORDER-LEFT: medium none; PADDING-TOP: 3pt; BORDER-BOTTOM: medium none">
<P class=MsoNormal><B><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: 'Tahoma','sans-serif'">From:</SPAN></B><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: 'Tahoma','sans-serif'">
bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <B>On Behalf Of </B>Matutinovic,
Luka<BR><B>Sent:</B> Thursday, June 04, 2009 12:52 PM<BR><B>To:</B>
bldg-sim@lists.onebuilding.org;
bldg-rate@lists.onebuilding.org<BR><B>Subject:</B> Re: [Bldg-sim] Modelling
chillers at non-standard operating conditions as per Appendix
G<o:p></o:p></SPAN></P></DIV></DIV>
<P class=MsoNormal><o:p> </o:p></P>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Univers">Thanks to Linda and
Bill for helping me out with this issue. As far as App G is concerned,
there is a specific set of condenser and chiller temperatures and condenser
flows that must be used in the reference building that represent ARI standard
conditions for which the COP is 6.1 (for centrifugal chillers > 300
tons). Therefore the reference building always operates at standard
conditions, while the proposed building's performance varies depending on
specific operating conditions.</SPAN><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal> <o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Univers">While this is
tantamount to asking someone to model the proposed building with a Chicago
weather file, compare it to a reference building with a Miami weather file
and require you to reduce cooling use, the rules are at present
clear. Unreasonable, but clear.</SPAN><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal> <o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Univers">So, my question to
the design/simulation community is this: </SPAN><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Univers">Has anyone been able
to spec a large centrifugal chiller (900-1500 tons) with a full load COP
matching or at least approaching 6.1, for a Zone 1 climate? (Specifically
my design conditions are 122F db, 86F wb, 42/57F CHW, 95/105 CW) If
so, if you could please post the spec sheet that would be fantastic.
Unfortunately the manufacturers don't post this kind of performance data so
a call to the local rep is needed to produce project specific
data.</SPAN><o:p></o:p></P></DIV>
<P class=MsoNormal><o:p> </o:p></P>
<DIV class=MsoNormal style="TEXT-ALIGN: center" align=center>
<HR align=center width="100%" SIZE=2>
</DIV>
<P class=MsoNormal style="MARGIN-BOTTOM: 12pt"><B><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: 'Tahoma','sans-serif'">From:</SPAN></B><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: 'Tahoma','sans-serif'"> Matutinovic, Luka
<BR><B>Sent:</B> Tuesday, June 02, 2009 7:28 PM<BR><B>To:</B>
bldg-sim@lists.onebuilding.org;
'bldg-rate@lists.onebuilding.org'<BR><B>Subject:</B> Modelling chillers at
non-standard operating conditions as per Appendix G</SPAN><o:p></o:p></P>
<DIV>
<P class=MsoNormal><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Univers">Hello
All,</SPAN><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal> <o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Univers">I have a
question regarding the minimum centrifugal chiller efficiencies for conditions
not covered by ASHRAE 90.1-2004 section 6.4.1.2. Specifically, I'm trying
to model a chiller for a building in a hot humid climate. The specified
operating conditions for the condenser EWT are 95ºF (35ºC), which
is beyond the range of conditions covered by ASHRAE.</SPAN><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal> <o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Univers">In this
case, what should I use for the minimum chiller efficiency in my reference
building? Do I still have to follow Appendix G section G3.1.3.11 which
states that my condenser supply temp shall be the lower of 84ºF (29ºC)
or 10ºF (5.6ºC) approach to design wet-bulb. The wet-bulb in this
climate is 86ºF (30ºC), so the 10ºF approach is therefore 96ºF,
which means my condenser supply temp (EWT) shall be 84ºF (29ºC), the lower
of the two. At this condenser EWT, the minimum ASHRAE efficiencies from
Table 6.8.1J vary depending on condenser flow. Since condenser flow is not
specified by Appendix G, should I simply used the Kadj equations at the bottom
of that table? If that's the case, the condenser DT is 15ºF (8ºC) and the
Lift is 41ºF (22.7ºC) and I arrive at an adjustment factor Kadj of 0.88.
Applied to my standard COP of 6.1, I get a COP of 5.4.
</SPAN><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal> <o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Univers">My issue
with this approach is that this COP is very difficult to achieve at our
operating conditions. In my opinion, this is an unfair comparison for
chillers in very hot humid climates since Appendix G is prescribing operating
conditions which are considerably more "temperate" than the extreme conditions
under which our chillers will operate. We can realistically achieve a COP
of 5.1. In this climate, cooling is a dominant load, yet due to Appendix G
"rules", it will be very difficult to meet the LEED energy prerequisite, since
our chiller are worse than reference.</SPAN><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal> <o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Univers">Finally,
I'm assuming that since ASHRAE does not cover this operating range, I don't have
to worry about meeting the mandatory provisions for efficiency listed in Tables
6.8.1H, I and J in my proposed building, ie there is no minimum chiller
efficiency for this range.</SPAN><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal> <o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Univers">Any help
in this matter would be much appreciated. If I've missed something in my
calculations or wasn't clear enough, please let me know because this issue is a
big concern to our project.</SPAN><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal
style="MARGIN-LEFT: 5.25pt"> <o:p></o:p></P></DIV></DIV></DIV></BODY></HTML>