[Bldg-sim] FW: Ice storage chilling system - getting LEED points?

[Keith Swartz]

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.

 

Sincerely,

Keith Swartz, PE, LEED(r) AP

Energy Center of Wisconsin

455 Science Drive

Suite 200

Madison, WI 53711

 

Phone: 608-238-8276 ext. 123

Fax:     608-238-0523

www.ecw.org <http://www.ecw.org/> 

The Energy Center of Wisconsin is an independent, nonprofit organization
that seeks solutions to energy challenges.

________________________________

From: William Bahnfleth [mailto:wbahnfleth at psu.edu] 
Sent: Sunday, March 23, 2008 1:36 PM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Ice storage chilling system - getting LEED
points?

 

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.

Variable speed compressors and thermal storage are a good match because
VS operation maximized the impact of a lift reduction.

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.

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.

Bill Bahnfleth

At 01:41 PM 3/23/2008, Wyman, Kevin L            UTPWR wrote:



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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.


Kevin L. Wyman, P.E.
LEED AP
On-Site Power Product Management
UTC Power
195 Governor's Highway
South Windsor, CT 06074
(860) 727-7020 (V)
(860) 660-0723 (F)
(860) 882-9595 (M)
Kevin.wyman at utcpower.com

----- Original Message -----
From: bldg-sim-bounces at lists.onebuilding.org
<bldg-sim-bounces at lists.onebuilding.org>
To: bldg-sim at lists.onebuilding.org <bldg-sim at lists.onebuilding.org>
Sent: Sun Mar 23 09:32:47 2008
Subject: Re: [Bldg-sim] Ice storage chilling system - getting LEED
points?

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.

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.

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.

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.

David

________________________________

From: bldg-sim-bounces at lists.onebuilding.org on behalf of Sasa Pantic
Sent: Sat 3/22/2008 2:21 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Ice storage chilling system - getting LEED points?


Dear colleagues,

I would kindly ask for an information please.
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.

Could I get LEED credits in Energy and Atmosphere section for reducing
the cooling cost?

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.
I gues I could get more LEED credits for being environmentally friendly?

Please advise.
Thanks muchly.

Regards Sasa Pantic



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_________________________________________________

William P. Bahnfleth, PhD, PE, FASHRAE
Professor of Architectural Engineering
Director, Indoor Environment Center

The Pennsylvania State University 
104 Engineering Unit A
University Park, PA 16802 USA

voice: 814.863.2076 / fax: 814.863.4789 
e-mail:  wbahnfleth at psu.edu
http://www.engr.psu.edu/ae/faculty/bahnfleth/
<http://www.engr.psu.edu/ae/faculty/bahnfleth/> 
http://www.engr.psu.edu/ae/iec/ <http://www.engr.psu.edu/ae/iec/> 
_________________________________________________ 
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