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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>
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<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>
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<div>_________________________________________________</div>
<br>
<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>
<br>
<div>voice: 814.863.2076 / fax: 814.863.4789 </div>
<div>e-mail: wbahnfleth@psu.edu</div>
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