Transcript Overview of Collected Integrated Chiller Retrofit Case Studies Dr. Lisa Gartland (510) 595-7674,

Overview of Collected Integrated
Chiller Retrofit Case Studies
Dr. Lisa Gartland
(510) 595-7674, [email protected]
Integrated Chiller Retrofit Case Studies
• Cool $ense workshops have been held
around the country
– Boston, Denver, San Diego, Kansas City,
Atlanta, and Washington D.C.
• Case studies collected in each region
– most are highly integrated retrofits
– all exemplify aspects of the Cool $ense message
Integrated Chiller Retrofit Case Studies
• Overview of collected case studies
–
–
–
–
–
chiller retrofit/replacement examples
cooling system improvement example
building load reduction example
integrated retrofit economics
how retrofits can be improved
• Details of individual case studies are
on the Cool $ense web site
– http://eetd.lbl.gov/CoolSense
Integrated Chiller Retrofit Case Studies
Chiller Retrofits/Replacements
• Most of my case studies start with and keep
electric centrifugal chillers
– don’t often switch to gas-fired or absorption chillers
• Significant efficiency gains
– original full-load efficiencies of 0.72 to 0.90 kW/ton
– replacement efficiencies of 0.48 to 0.65 kW/ton
• Total capacity stays about the same
– 260 tons/100,000 square feet “before”
245 tons/100,000 square feet “after”
Integrated Chiller Retrofit Case Studies
Chiller Retrofit Example
Lawrence Street Center
Denver, CO
office space
radio stations
140,000 square feet
14 stories
built in 1982
Chiller “Before”
•
•
•
•
•
400 ton electric chiller
R-11 refrigerant
0.72 kW/ton efficiency
Less than 15 years old
Operating at 60% capacity
Integrated Chiller Retrofit Case Studies
Lawrence Street Center - Chiller Retrofit
Chiller “After”
• Driveline retrofit, replaces the driveline, including
starter, motor, compressor, purge unit and controls
• Kept old heat exchanger
– checked condition of shells & tubes condition with
eddy current testing of condenser & evaporator
• Capacity reduced from 400 tons to 290 tons
• Full load efficiency of 0.59 kW/ton
Retrofit
Cost
Rebate
$ 94,000
$ 32,000
Annual
Energy
Savings
$ 12,500
Payback
Period
(years)
4.96
Integrated Chiller Retrofit Case Studies
Chiller Replacement Example
Kansas City
International
Airport
3 terminals, 1 office
1,000,000 square feet
2 stories
built in 1970
Chiller “Before”
• Two 2750-ton electric chillers
– installed in 1970, estimated efficiency 0.85 - 0.9 kW/ton at full load
– R-12 refrigerant, no refrigerant containment system
• Never run the second chiller & often running at part-loads
• 48-49°F discharge water temperatures, not meeting design 42°F
Integrated Chiller Retrofit Case Studies
Kansas City Intl Airport - Chiller Replacement
Chiller “After”
• Three 1500-ton electric chillers
–
–
–
–
more flexible staging capability than with the 2 larger chillers
R-134a refrigerant
efficiency of 0.65 kW/ton at full load
saving about 0.25 kW/ton
• Running closer to full-load capacities for higher efficiencies
• Meeting 42°F design water discharge temperature
New Chillers
Purchase &
Installation
Cost ($)
$800,000
Annual
Energy
Savings ($)
$63,500
Payback
Period
(years)
12.6
Integrated Chiller Retrofit Case Studies
Cooling System Improvements
• Most common cooling system improvements
–
–
–
–
–
replacement of cooling towers
new, more efficient fans, pumps & motors
addition of economizer or evaporative cooling
new air handler units with variable volumes
automated control systems to integrate building
operation with outside conditions and indoor loads
• Rarer cooling system improvements
– thermal storage
– heat recovery systems
Integrated Chiller Retrofit Case Studies
Cooling System Improvements
Rhode Island Hospital Trust
Rhode Island
office space
computer operations
140,000 square feet
1 story
built in 1983
“Before” Scenario
•
•
•
•
•
Need to reduce demand and on-peak electricity consumption
One 275 ton electric chiller & 208 tons of rooftop units
CFC-11 refrigerant, 0.75 kW/ton efficiency
Building expanding by 50%, or 70,000 square feet
Plenty of room for equipment
Integrated Chiller Retrofit Case Studies
Rhode Island Hospital Trust Building
• Ice storage system
– 390 ton brine chiller, three 761 ton-hour ice banks
– create ice at night, cooling load diverted to ice banks during day
• 390 ton high efficiency brine chiller
– meets summer loads in building and computer room
• Rooftop units originally cooled computer room all year
– retrofit with chilled water coils & hooked up to heat exchanger
– original rooftop units kept for backup capability
• Added variable speed drives, high efficiency motors, EMCS
• T-8 fluorescent lights used with occupancy sensors
Project
Cost
$1,200,000
Rebate
$ 575,000
Annual Energy
Savings
$ 196,000
Payback
Period
3.2 years
Integrated Chiller Retrofit Case Studies
Building Load Reductions
• Lighting Improvements
–
–
–
–
most projects add T-8 lamps & electronic ballasts
fewer use low energy incandescents & exit signs
occupancy sensors could be used more often
additional daylighting rarely introduced and/or
compensated for by lighting sensors
• Wall and window upgrades to reduce loads
– low-emissivity films used fairly commonly
– insulation is rarely increased
– surface reflectivities never increased
Integrated Chiller Retrofit Case Studies
Building Load Reduction Example
New York Life Building
Kansas City, MO
office space
220,000 square feet
12 stories
built in 1888
Envelope Measures
• New energy-efficient windows
– double-pane, low-e, insulated frames
– custom-made operable windows
• Exterior masonry walls
– R-11 fiberglass insulation added
• New roof with R-20 insulation
• 5-7 year paybacks
Integrated Chiller Retrofit Case Studies
Kansas City’s New York Life Building
Lighting Measures
• Overhead lighting
– T8 Fluorescent tubes
– solid-state, low-energy, dimmable ballasts
• Daylighting
– ceilings slope down from windows to reflect light into interior
– interior light shelves, light reflective colors
• Computer-controlled system
– adjust overhead light levels according to the amount of daylight
– occupancy sensors turn off lights when no one is present
• 3-4 year paybacks
•Saved $0.50 to $0.80 per square foot
•Comfortable, modern office building with historic character
Integrated Chiller Retrofit Case Studies
Integrated Retrofit Economics Example
Worcester Polytechnic Institute
Worcester, MA
Gordon Library & Fuller Laboratory
library and computer laboratory
128,700 square feet total
4 & 6 stories
built in 1958 & 1985
Integrated Retrofit
Measures
Cost
($)
New Chiller
AHU Controls
EM S plus VSD pumps
Lighting Retrofits
CoolingT ower/HeatEx
T otal
110,240
6,900
75,000
159,600
221,400
$573,140
Utility
Annual
Payback
Incentive
Energy
Period
($)
Savings( $) ( years)
4,250
6,430
16.5
4,430
560
4.4
6,670
4,650
14.7
43,940
38,710
3.0
141,280
21,070
3.8
$200,570
$71,420
5.2
Integrated Chiller Retrofit Case Studies
Improving Integrated Retrofits - Chiller Sizing
New 600 ton electric centrifugal
chiller, about to be installed
in Boston’s Hurley Building.
This chiller replaces an equal
capacity chiller, despite lighting
load reductions and increased
system efficiencies!
• Know your building loads both
before & after retrofit work!!
• Downsize, rightsize or stage
your chillers to most efficiently
meet these loads!
Integrated Chiller Retrofit Case Studies
Improving Integrated Retrofits - Higher Motivations
• Most common motivations
–
–
–
–
CFC phaseouts
equipment age or imminent failure
high utility bills or increasing fuel costs
rebate programs
• Motivations leading to the “best” retrofits
– comfort or indoor air quality problems
– environmental concerns or energy efficiency goals
– extensive building renovation
Integrated Chiller Retrofit Case Studies
Set Challenging Goals
Green Building
San Diego, CA
office space
73,000 square feet
3 stories
built in 1981
• Goal of four year payback in terms of energy savings
• High levels of energy & environmental performance
– use less than 9 kWh per square foot annually
– use environmentally friendlier materials
• Model for sustainable building practices in San Diego
Integrated Chiller Retrofit Case Studies
Green Building’s Goals Were Met
High Efficiency Heat Pumps
New Lobby Heat Pumps
New Cooling Towers
VSDs on Pumps
Reduced Supply & Outside Air
Light Fixture Revisions
Lighting Controls
Occupancy Sensor Interlock
CRT Occupancy Sensors
Window Films
Panels in Sloped Glass Offices
Total
Purchase &
Installation Cost
($)
15,000
10,250
57,000
18,100
0
40,100
45,500
5,100
21,000
46,000
9,700
$267,750
Total
Savings
($)
13,700
1,400
1,650
14,900
7,100
13,100
6,700
2,100
5,900
3,850
750
$71,150
Payback
Period
(years)
1.1
7.3
34.5
1.2
0.0
3.1
6.8
2.4
3.6
11.9
12.9
3.8
•Used 8.0 kWh/sq.ft, meeting 9kWh/sq.ft. goal
Integrated Chiller Retrofit Case Studies
Summary
• Integrated retrofit projects CAN combine
– high energy efficiency
– innovative technology for chillers, thermal
storage, air handling, lighting, etc.
– financial viability
• When it’s time to replace your chiller
– set high goals for your building, then meet them!