Overview of Collected Integrated Chiller Retrofit Case Studies Dr. Lisa Gartland (510) 595-7674,...
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Transcript of Overview of Collected Integrated Chiller Retrofit Case Studies Dr. Lisa Gartland (510) 595-7674,...
Overview of Collected Integrated Chiller Retrofit Case
StudiesDr. 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 CenterDenver, CO
office space radio stations140,000 square feet14 storiesbuilt in 1982
• 400 ton electric chiller• R-11 refrigerant• 0.72 kW/ton efficiency• Less than 15 years old• Operating at 60% capacity
Chiller “Before”
Integrated Chiller Retrofit Case Studies
Lawrence Street Center - Chiller Retrofit
• 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
RetrofitCost
Rebate AnnualEnergySavings
PaybackPeriod(years)
$ 94,000 $ 32,000 $ 12,500 4.96
Chiller “After”
Integrated Chiller Retrofit Case Studies
Chiller Replacement Example
Kansas City International Airport
3 terminals, 1 office1,000,000 square feet2 storiesbuilt in 1970
• 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
Chiller “Before”
Integrated Chiller Retrofit Case Studies
Kansas City Intl Airport - Chiller Replacement
• 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
Chiller “After”
Purchase &Installation
Cost ($)
AnnualEnergy
Savings ($)
PaybackPeriod(years)
New Chillers $800,000 $63,500 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 TrustRhode Island
office space computer operations140,000 square feet 1 storybuilt in 1983
• 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
“Before” Scenario
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
ProjectCost
Rebate Annual EnergySavings
PaybackPeriod
$1,200,000 $ 575,000 $ 196,000 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
• 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
Envelope Measures
Integrated Chiller Retrofit Case Studies
Kansas City’s New York Life Building
• 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
Lighting Measures
•Saved $0.50 to $0.80 per square foot•Comfortable, modern office building with historic character
Integrated Chiller Retrofit Case Studies
Integrated Retrofit Economics Example
Worcester Polytechnic InstituteWorcester, MA
Gordon Library & Fuller Laboratorylibrary and computer laboratory128,700 square feet total4 & 6 storiesbuilt in 1958 & 1985
Integrated RetrofitMeasures
Cost($)
UtilityIncentive
($)
AnnualEnergy
Savings($)
PaybackPeriod(years)
New Chiller 110,240 4,250 6,430 16.5AHU Controls 6,900 4,430 560 4.4
EMS plus VSD pumps 75,000 6,670 4,650 14.7Lighting Retrofits 159,600 43,940 38,710 3.0
CoolingTower/HeatEx 221,400 141,280 21,070 3.8Total $573,140 $200,570 $71,420 5.2
Integrated Chiller Retrofit Case Studies
Improving Integrated Retrofits - Chiller Sizing
New 600 ton electric centrifugal chiller, about to be installed in Boston’s Hurley Building.
This chiller replaces an equal capacity chiller, despite lighting load reductions and increased system efficiencies!
• Know your building loads both before & after retrofit work!!
• Downsize, rightsize or stage your chillers to most efficiently meet these loads!
Integrated Chiller Retrofit Case Studies
Improving Integrated Retrofits - Higher Motivations
• Most common motivations– CFC phaseouts– equipment age or imminent failure– high utility bills or increasing fuel costs– rebate programs
• Motivations leading to the “best” retrofits– comfort or indoor air quality problems– environmental concerns or energy efficiency
goals– extensive building renovation
Integrated Chiller Retrofit Case Studies
Set Challenging Goals
Green Building San Diego, CA
office space73,000 square feet3 storiesbuilt in 1981
• Goal of four year payback in terms of energy savings• High levels of energy & environmental performance
– use less than 9 kWh per square foot annually– use environmentally friendlier materials
• Model for sustainable building practices in San Diego
Integrated Chiller Retrofit Case Studies
Green Building’s Goals Were Met
•Used 8.0 kWh/sq.ft, meeting 9kWh/sq.ft. goal
Purchase &Installation Cost
($)
TotalSavings
($)
PaybackPeriod(years)
High Efficiency Heat Pumps 15,000 13,700 1.1New Lobby Heat Pumps 10,250 1,400 7.3
New Cooling Towers 57,000 1,650 34.5VSDs on Pumps 18,100 14,900 1.2
Reduced Supply & Outside Air 0 7,100 0.0Light Fixture Revisions 40,100 13,100 3.1
Lighting Controls 45,500 6,700 6.8Occupancy Sensor Interlock 5,100 2,100 2.4
CRT Occupancy Sensors 21,000 5,900 3.6Window Films 46,000 3,850 11.9
Panels in Sloped Glass Offices 9,700 750 12.9Total $267,750 $71,150 3.8
Integrated Chiller Retrofit Case StudiesSummary
• 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!