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<body>
That is true, but air to air heat recovery and/or reset to improve
economizer availability can both help to reduce that problem. DOAS
systems are quite efficient even though they can't provide full
economizer cooling--and they need the low temperature in some cases to do
the dehumidification. No simple answers.<br><br>
Bill<br><br>
At 03:34 AM 3/27/2008, Bill wrote:<br>
<blockquote type=cite class=cite cite=""><font size=2 color="#0000FF">One
thing to be careful of when considering the impact of low temperature air
distribution on energy use: Depending on climate, many hours of
economizer cooling may be lost. This can be a huge impact in mild
climates, and should be evaluated in all climates that have moderate
temperatures for at least a few months a year. The increased plant
energy use from the loss of "free" cooling can dwarf the air
transport savings, unless this is accounted for in the design and control
of the air systems.<br>
</font> <br>
<font size=2 color="#0000FF">--Bill<br>
</font> <br>
<font face="Tahoma" size=2>William E. Koran, P.E.</font> <br>
<font face="Tahoma" size=2>Senior Engineer</font> <br>
<font face="Tahoma" size=2>Q u E S T</font> <br>
<font face="Tahoma" size=1>Quantum Energy Services and
Technologies</font><font size=2> <br>
</font><font face="Tahoma" size=2>Voice: 503-557-7828</font> <br>
<font face="Tahoma" size=2>Fax: 510-540-7268</font> <br>
<font face="Tahoma" size=2>Web:</font>
<a href="http://www.quest-world.com/">
<font face="Tahoma" size=2 color="#0000FF"><u>www.quest-world.com</a><br>
</u></font> <br>
<hr>
<font face="Tahoma" size=2><b>From:</b>
bldg-sim-bounces@lists.onebuilding.org
[<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" eudora="autourl">
mailto:bldg-sim-bounces@lists.onebuilding.org</a>] <b>On Behalf Of
</b>Keith Swartz<br>
<b>Sent:</b> Wednesday, March 26, 2008 7:04 AM<br>
<b>To:</b> bldg-sim@lists.onebuilding.org<br>
<b>Subject:</b> [Bldg-sim] FW: Ice storage chilling system - getting LEED
points?<br>
</font><br>
<font size=2 color="#000080">Bill makes a good point about taking
advantage of the lower temperature of the ice system. I worked on a
project that had an ice storage system that took advantage of the colder
temperature. We made the chilled water supply temperature 38F and return
temperature 62F (DeltaT=24F). The pumping power saved was pretty
significant, since the chilled water had to be pumped underground more
than 1200 feet from the Chiller Plant to the main building. The lower
chilled water temperature allowed me to use lower supply air temperature
at the air handlers, which allowed me to select smaller air handlers (due
to lower cfm), which allowed me to actually fit the air handlers into the
allotted space! So there are more benefits than just energy cost
benefits…if you take advantage of the opportunities.<br>
</font><br>
<font size=2 color="#000080"> <br>
</font><br>
<font size=2 color="#000080">Sincerely,<br>
</font><br>
<font size=2 color="#000080">Keith Swartz, PE, LEED® AP<br>
</font><br>
<font size=2 color="#000080">Energy Center of Wisconsin<br>
</font><br>
<font size=2 color="#000080">455 Science Drive<br>
</font><br>
<font size=2 color="#000080">Suite 200<br>
</font><br>
<font size=2 color="#000080">Madison, WI 53711<br>
</font><br>
<font size=2 color="#000080"> <br>
</font><br>
<font size=2 color="#000080">Phone: 608-238-8276 ext. 123<br>
</font><br>
<font size=2 color="#000080">Fax:
608-238-0523<br>
</font><br>
<font size=2 color="#000080"><a href="http://www.ecw.org/">www.ecw.org</a>
<br>
</font><br>
<font size=2 color="#000080">The Energy Center of Wisconsin is an
independent, nonprofit organization that seeks solutions to energy
challenges.<br>
<hr>
<div align="center"></font></div>
<font face="Tahoma" size=2><b>From:</b> William Bahnfleth
[<a href="mailto:wbahnfleth@psu.edu" eudora="autourl">
mailto:wbahnfleth@psu.edu</a>] <br>
<b>Sent:</b> Sunday, March 23, 2008 1:36 PM<br>
<b>To:</b> bldg-sim@lists.onebuilding.org<br>
<b>Subject:</b> Re: [Bldg-sim] Ice storage chilling system - getting LEED
points?<br>
</font><br>
<font face="Times New Roman, Times"> <br>
</font><br>
<font face="Times New Roman, Times">I doubt that night-time wet bulb
depression is sufficient in most places to compensate for the difference
between saturated evaporating temperatures associated with typical
chilled water and ice production systems. However, break-even seems
to be attainable for air-cooled systems.<br><br>
Variable speed compressors and thermal storage are a good match because
VS operation maximized the impact of a lift reduction.<br><br>
A key to saving energy with ice storage or any other low temperature
production scheme is to take advantage of the low temperature
source. The most common examples are low temperature water
distribution and low temperature air distribution to achieve larger
temperature differences and reduce transport energy consumption.<br><br>
Other benefits of thermal storage that are significant, but
frequently poorly quantified, if quantified at all, are load management
effects--more efficient part loading, preferential loading of more
efficient equipment, etc.<br><br>
Bill Bahnfleth<br><br>
At 01:41 PM 3/23/2008, Wyman, Kevin
L UTPWR
wrote:<br><br>
Content-class: urn:content-classes:message<br>
Content-Type: multipart/alternative;<br>
<x-tab> </x-tab>
boundary="----_=_NextPart_001_01C88D0D.0FE7F528"<br><br>
</font><font size=2>Agree with everything David pointed out. While ice
making chillers would use more energy to create the colder temperatures
needed for phase change, they often do this at night when cooling tower
doesn't work as hard and ambients drop (in some climates) so net energy
is often less. In other words, the kWh consumption can be less as well as
peak kW savings under rate tarriff considerations.<br><br>
<br>
Kevin L. Wyman, P.E.<br>
LEED AP<br>
On-Site Power Product Management<br>
UTC Power<br>
195 Governor's Highway<br>
South Windsor, CT 06074<br>
(860) 727-7020 (V)<br>
(860) 660-0723 (F)<br>
(860) 882-9595 (M)<br>
Kevin.wyman@utcpower.com<br><br>
----- Original Message -----<br>
From: bldg-sim-bounces@lists.onebuilding.org
<bldg-sim-bounces@lists.onebuilding.org><br>
To: bldg-sim@lists.onebuilding.org
<bldg-sim@lists.onebuilding.org><br>
Sent: Sun Mar 23 09:32:47 2008<br>
Subject: Re: [Bldg-sim] Ice storage chilling system - getting LEED
points?<br><br>
For EAC1, the comparison is about energy cost. The ice storage will
save money IF you have time-of-day electricity rates in place. If
you are using the EIA state average rate data, it won't show a
savings.<br><br>
Ice storage actually uses more energy not less -- you can get more out of
the ice, but remember that you have to spend the same amount of
refrigeration energy to make the ice, plus the chiller will be working
against unfavorable temperatures and fluid properties which will use more
compressor energy compared to conventional chilled water, per
ton-hr.<br><br>
Maybe there is merit if you can say what savings there are from
night-time electricity compared to day-time electricity, or if there is
some major problem with electricity distribution in your area.<br><br>
Your client may be interested in first cost savings if you design a
partial storage system, but don't expect any LEED credit for
that.<br><br>
David<br><br>
________________________________<br><br>
From: bldg-sim-bounces@lists.onebuilding.org on behalf of Sasa
Pantic<br>
Sent: Sat 3/22/2008 2:21 PM<br>
To: bldg-sim@lists.onebuilding.org<br>
Subject: [Bldg-sim] Ice storage chilling system - getting LEED
points?<br><br>
<br>
Dear colleagues,<br><br>
I would kindly ask for an information please.<br>
I am thinking of designing an ice storage chilling system that would
generate ice at night, during low electricity rates, and will be used
during the following day for to reduce peak cooling demands of the
building.<br><br>
Could I get LEED credits in Energy and Atmosphere section for reducing
the cooling cost?<br><br>
In addition, taking into account that ice can absorb more heat than that
of water and therefore will lead to much more chilling capaciity or
"tons" of refrigeration from the same size/horsepower rating of
compressors than a conventional type of chiller.<br>
I gues I could get more LEED credits for being environmentally
friendly?<br><br>
Please advise.<br>
Thanks muchly.<br><br>
Regards Sasa Pantic<br><br>
<br><br>
________________________________<br><br>
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William P. Bahnfleth, PhD, PE, FASHRAE<br>
Professor of Architectural Engineering<br>
Director, Indoor Environment Center<br><br>
The Pennsylvania State University <br>
104 Engineering Unit A<br>
University Park, PA 16802 USA<br><br>
voice: 814.863.2076 / fax: 814.863.4789 <br>
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<div>William P. Bahnfleth, PhD, PE, FASHRAE</div>
<div>Professor of Architectural Engineering</div>
<div>Director, Indoor Environment Center</div>
<br>
<div>The Pennsylvania State University </div>
<div>104 Engineering Unit A</div>
<div>University Park, PA 16802 USA</div>
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