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<DIV><FONT face=Univers size=2><SPAN class=390430722-02062009>Hello
All,</SPAN></FONT></DIV>
<DIV><FONT face=Univers size=2><SPAN
class=390430722-02062009></SPAN></FONT> </DIV>
<DIV><FONT face=Univers size=2><SPAN class=390430722-02062009>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 </SPAN></FONT><FONT face=Univers size=2><SPAN class=390430722-02062009>beyond
the range of conditions covered by ASHRAE.</SPAN></FONT></DIV>
<DIV><FONT face=Univers size=2><SPAN
class=390430722-02062009></SPAN></FONT> </DIV>
<DIV><FONT face=Univers size=2><SPAN class=390430722-02062009>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></FONT></DIV>
<DIV><FONT face=Univers size=2><SPAN
class=390430722-02062009></SPAN></FONT> </DIV>
<DIV><FONT face=Univers size=2><SPAN class=390430722-02062009>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></FONT></DIV>
<DIV><FONT face=Univers size=2><SPAN
class=390430722-02062009></SPAN></FONT><FONT face=Univers size=2><SPAN
class=390430722-02062009></SPAN></FONT> </DIV>
<DIV><FONT face=Univers size=2><SPAN class=390430722-02062009>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></FONT></DIV>
<DIV><FONT face=Univers size=2><SPAN
class=390430722-02062009></SPAN></FONT> </DIV>
<DIV><FONT face=Univers size=2><SPAN class=390430722-02062009>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></FONT></DIV>
<DIV><FONT face=Univers size=2><SPAN
class=390430722-02062009></SPAN></FONT> </DIV>
<DIV><FONT face=Univers size=2><SPAN class=390430722-02062009>Many
thanks,</SPAN></FONT></DIV>
<DIV><FONT face=Univers size=2><SPAN
class=390430722-02062009></SPAN></FONT> </DIV>
<DIV><FONT face=Univers size=2><SPAN class=390430722-02062009>
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<P class=MsoNormal dir=ltr align=left><B><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: Arial">Luka Matutinovic, </SPAN></B><SPAN
class=SpellE><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: Arial">B.A.Sc</SPAN></SPAN><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: Arial">., LEED<SUP>®</SUP> AP</SPAN></P>
<P class=MsoNormal><EM><SPAN style="FONT-SIZE: 7.5pt; FONT-FAMILY: Arial">Green
Building Consultant</SPAN></EM><I><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><BR></SPAN></I><EM><SPAN
style="FONT-SIZE: 6pt; FONT-FAMILY: Arial"> </SPAN></EM><I><SPAN
style="FONT-SIZE: 6pt; FONT-FAMILY: Arial"><BR></SPAN></I><SPAN
style="FONT-SIZE: 7.5pt; FONT-FAMILY: Arial">T.
416.487.5257 ext. 317<SPAN class=GramE> </SPAN><BR>F.
416.487.9766 <BR>Toll Free 1.888.425.7255<BR>www.halsall.com
<BR></SPAN><SPAN style="FONT-SIZE: 6pt"><BR></SPAN><B><SPAN
style="FONT-SIZE: 9pt; FONT-FAMILY: Arial">HALSALL ASSOCIATES LTD.
<BR></SPAN></B><?xml:namespace prefix = st1 ns =
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<BR></SPAN><SPAN><BR><SPAN style="FONT-SIZE: 10px"><STRONG><FONT
face=Verdana>‘Best Workplaces in Canada’ <BR></FONT></STRONG><I><FONT
face=Verdana>2009 Globe and Mail</FONT><BR></I></SPAN></SPAN><SPAN
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