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

[Bill]

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.
 
--Bill
 
William E. Koran, P.E. 
Senior Engineer 
Q u E S T 
Quantum Energy Services and Technologies 
Voice: 503-557-7828 
Fax: 510-540-7268 
Web:  <http://www.quest-world.com/> www.quest-world.com
 
  _____  

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Keith Swartz
Sent: Wednesday, March 26, 2008 7:04 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] FW: Ice storage chilling system - getting LEED points?



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, LEEDR 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/iec/
_________________________________________________ 
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