ASHRAE Journal - April 2013 - 20

temperatures expected. Building ice
Boiler/Chiller
GCHP
GCHP with TES
requires chilled fluid as low as 22°F
Interior Mechanical System Cost
$2,500,000
$2,400,000
$2,400,000
(–6°C).
In a central plant, water flow from
Deduct for Reduced Heat Pump Capacity
–
–
($70,000)
the evaporator is directed by motorAdd for Ice Storage Tanks
–
–
$58,000
ized valves to either the GHX when
drawing heat from the earth, to the
Add for GHX
–
$417,000
$354,000
building loads (i.e., air handlers, raSystem Cost
$2,500,000
$2,817,000
$2,742,000
diant floor cooling, etc.), or to the
ice storage tanks. Water flow from
U.S. Federal 10% Tax Incentive
–
($281,700)
($274,200)
the condenser is directed either to the
Cost Difference from Conventional
–
$35,300
($32,200)
GHX when cooling the building, or to
terminal devices when heating.
Predicted Energy Cost
$33,616
$21,645
$18,946
Using several heat pump modules, and
Energy Cost Savings
–
$11,971
$14,670
directing the flow from each module independently, allows the varying loads of
Simple Payback
–
2.9 Years
0 Years
the building to be met. One module can
build ice and provide heat to the build- Table 7: Summary of capital cost to install conventional HVAC system compared
ing, and a second can draw heat from the to GCHP and GCHP integrated with ice storage. The following assumptions were
GHX to provide additional heat.
used: Cost of conventional mechanical system: $25/ft2 ($269/m2), cost of GCHP
A centralized water-water heat pump interior system: $23/ft2 ($247/m2) cost of GHX: $22/ft ($72/m), cost of gas:
system provides hot and chilled water $1.08/ccf ($0.38/m3 or $10.20/GJ), cost of electricity: $0.08/kWh with deto the building simultaneously. Rather mand charge $16.00/kW. Energy cost was calculated using 8,760 hour energy
than rejecting energy into the ground, it model. Additional incentives based on accelerated capital cost allowance are not
can provide space heating in other areas included in calculations, and may significantly improve economic analysis in the
of the building or produce hot water. U.S. and Canada for some owners. (Note: construction costs, GHX costs and utility
To build ice or chilled water in storage rates vary significantly from one area to another and because of design details
tanks requires the heat pumps to run and equipment selection, may not represent costs in your area. These variations
more hours, significantly increasing op- along with possible incentives available in your area can have an impact on
portunities for simultaneous heating and financial models.)
cooling and improving system efficiency, even though when strictly building ice, the heat pumps are
° Are “time of use” rates available and at what time of day
less efficient.
or week?
Several factors should be considered before integrating
° Are there peak electrical demand penalties at specific
chilled water or ice storage tanks with a GCHP system:
times?
• Chilled water tanks or ice storage tanks add cost to the
° How many hours are available to build storage, and is the
mechanical system. This is offset by reducing chiller or heat equipment capacity specified adequate to recharge the storage
pump capacity.
in the time available?
• Heat pumps used to produce ice or low temperature wa° What is the chilling capacity of the specified equipment
ter operate less efficiently and with less capacity. Reduced when producing chilled water or ice for the storage tanks?
efficiency is offset if heat produced can be used simultane° Is the system designed to provide the peak cooling load with
ously.
only the chilled water or ice storage tanks, or is it designed to
• Chilled water tanks and ice storage tanks require space, supplement the cooling capacity of the chilled water plant?
and the weight of the filled tanks must be supported. In
° Will stored chilled water or ice be required to provide
some projects, tanks may be buried near the building or mission critical cooling?
placed on the roof, but consideration must be given to tank
° Does equipment specified provide the heating capacity replacement.
quired in the building, or will supplemental heating be required?
• If ice storage is selected, the system may require the same
° Is the system designed to provide chilled and hot water
fluid throughout the system, including the building piping sys- for simultaneous heating and cooling?
tem and the GHX. This will require adequate freeze protection
° Will the client have trained personnel capable of operatand may impact pump selection and pumping costs. Alterna- ing the system as intended?
tively , heat exchangers can be used to separate different parts
of the system.
Conclusions
• The control strategy must be considered carefully. ConsidIntegrating TES with a GCHP system can provide benefits in
erations include:
projects with large, predictable and intermittent peak heating
20

ASHRAE Journal

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April 2013



ASHRAE Journal - April 2013

Table of Contents for the Digital Edition of ASHRAE Journal - April 2013

ASHRAE Journal - April 2013
Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
Ground-Coupled Heat Pump and Energy Storage
Fan Efficiency Requirements for Standard 90.1-2013
Technology Award Case Studies:
Geothermal for 5 Ecosystems
Holistic HVAC Design
Standing Columns
Engineer’s Notebook
Data Centers
Emerging Technologies
IAQ Applications
Refrigeration Applications
Special Products
People
International Column
Energy Modeling
Products
Classified Advertising
Advertisers Index
ASHRAE Journal - April 2013 - ASHRAE Journal - April 2013
ASHRAE Journal - April 2013 - Cover2
ASHRAE Journal - April 2013 - 1
ASHRAE Journal - April 2013 - 2
ASHRAE Journal - April 2013 - Contents
ASHRAE Journal - April 2013 - Commentary
ASHRAE Journal - April 2013 - 5
ASHRAE Journal - April 2013 - Industry News
ASHRAE Journal - April 2013 - 7
ASHRAE Journal - April 2013 - 8
ASHRAE Journal - April 2013 - Letters
ASHRAE Journal - April 2013 - Meetings and Shows
ASHRAE Journal - April 2013 - 11
ASHRAE Journal - April 2013 - 12
ASHRAE Journal - April 2013 - 13
ASHRAE Journal - April 2013 - Ground-Coupled Heat Pump and Energy Storage
ASHRAE Journal - April 2013 - 15
ASHRAE Journal - April 2013 - 16
ASHRAE Journal - April 2013 - I1
ASHRAE Journal - April 2013 - I2
ASHRAE Journal - April 2013 - I3
ASHRAE Journal - April 2013 - I4
ASHRAE Journal - April 2013 - 17
ASHRAE Journal - April 2013 - 18
ASHRAE Journal - April 2013 - 19
ASHRAE Journal - April 2013 - 20
ASHRAE Journal - April 2013 - 21
ASHRAE Journal - April 2013 - 22
ASHRAE Journal - April 2013 - 23
ASHRAE Journal - April 2013 - Fan Efficiency Requirements for Standard 90.1-2013
ASHRAE Journal - April 2013 - 25
ASHRAE Journal - April 2013 - 26
ASHRAE Journal - April 2013 - 27
ASHRAE Journal - April 2013 - 28
ASHRAE Journal - April 2013 - 29
ASHRAE Journal - April 2013 - 30
ASHRAE Journal - April 2013 - 31
ASHRAE Journal - April 2013 - Geothermal for 5 Ecosystems
ASHRAE Journal - April 2013 - 33
ASHRAE Journal - April 2013 - 34
ASHRAE Journal - April 2013 - 35
ASHRAE Journal - April 2013 - 36
ASHRAE Journal - April 2013 - 37
ASHRAE Journal - April 2013 - 38
ASHRAE Journal - April 2013 - 39
ASHRAE Journal - April 2013 - Holistic HVAC Design
ASHRAE Journal - April 2013 - 41
ASHRAE Journal - April 2013 - 42
ASHRAE Journal - April 2013 - 43
ASHRAE Journal - April 2013 - 44
ASHRAE Journal - April 2013 - 45
ASHRAE Journal - April 2013 - 46
ASHRAE Journal - April 2013 - 47
ASHRAE Journal - April 2013 - Engineer’s Notebook
ASHRAE Journal - April 2013 - 49
ASHRAE Journal - April 2013 - 50
ASHRAE Journal - April 2013 - 51
ASHRAE Journal - April 2013 - 52
ASHRAE Journal - April 2013 - 53
ASHRAE Journal - April 2013 - Data Centers
ASHRAE Journal - April 2013 - 55
ASHRAE Journal - April 2013 - 56
ASHRAE Journal - April 2013 - 57
ASHRAE Journal - April 2013 - 58
ASHRAE Journal - April 2013 - 59
ASHRAE Journal - April 2013 - Emerging Technologies
ASHRAE Journal - April 2013 - 61
ASHRAE Journal - April 2013 - 62
ASHRAE Journal - April 2013 - 63
ASHRAE Journal - April 2013 - IAQ Applications
ASHRAE Journal - April 2013 - 65
ASHRAE Journal - April 2013 - 66
ASHRAE Journal - April 2013 - Refrigeration Applications
ASHRAE Journal - April 2013 - Special Products
ASHRAE Journal - April 2013 - People
ASHRAE Journal - April 2013 - International Column
ASHRAE Journal - April 2013 - 71
ASHRAE Journal - April 2013 - Energy Modeling
ASHRAE Journal - April 2013 - 73
ASHRAE Journal - April 2013 - Products
ASHRAE Journal - April 2013 - 75
ASHRAE Journal - April 2013 - 76
ASHRAE Journal - April 2013 - 77
ASHRAE Journal - April 2013 - 78
ASHRAE Journal - April 2013 - Classified Advertising
ASHRAE Journal - April 2013 - Advertisers Index
ASHRAE Journal - April 2013 - Cover3
ASHRAE Journal - April 2013 - Cover4
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