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Reliability and Energy Efficiency – Not Mutually Exclusive William TschudiPrincipal InvestigatorLawrence Berkeley National Laboratory
AcknowledgementsCalifornia Energy Commission
Pacific Gas and Electric Company
Uptime Institute
Critical Facilities Roundtable
Rumsey Engineers
RMI
E Source
Power Supply Manufacturers Association
Industry Partners (Too many to name all)
Subcontractors:
EYP Mission Critical Facilities, Ecos Consulting, EPRI-PEAC
Energy Intensive High-tech Buildings
Cleanrooms
Healthcare
Data Centers
Laboratories
We Also Operate Data Centers
Overview
Why Research Data Centers?• Utilities were receiving requests for
unrealistic power densities
• A lot of misinformation was (is?) circulating
• Large continually operating base loads
• We saw large energy efficiency opportunities in other High-Tech buildings
• Technology improvements are transferable to other building types
Prior Data Center Research• Research “roadmap” for the CA Energy
Commission
• Participation in design charrette organized by Rocky Mountain Institute
• Energy benchmarking and case studies for 14 data centers
• Market assessment in CA
Overview
Current Data Center Research Activities• Benchmarking and Best
Practices
• Investigate UPS Efficiency Improvement
• Investigate Power SupplyImprovement
• Develop performance metrics – computing horsepower and energy use
• Demonstration Projects
• Technology Transfer
Benchmarking
Energy Benchmarking• Benchmark (measure) energy use in 6-10
additional data centers
– Energy intensity and end-use– System and component efficiency– Efficiency improvement suggestions
• Solicit additional benchmarks from other sources
• Identify and analyze better performing systems and document in “Best Practices” summary
• Develop self-benchmarking protocol
local distribution lines
to the building, 480 V
HVAC system
lights, office space, etc.
UPS
PDU computer racks
backup generators
computerequipment
uninterruptible
load
Electricity Flows In Data Centers
Computer Load Dens ity
010203040506070
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Fac ility
W/s
q.f
t.
16
Distribution of Computer Room Power Reported to Uptime Institute
0.00
0.20
0.40
0.60
0.80
1.00
0 20 40 60 80 100
Computer room UPS power (Watts/square foot)
Fra
ctio
n of
tot
al f
loor
are
a in
sam
ple
1999
2000
2001
Number of facilities Total floor area
Computer room power density
Million square feet W/square foot1999 35 1.55 22.92000 38 1.72 22.42001 48 1.86 25.3
Source: Uptime Institute, 2002.
Benchmarking
Both LBNL and Uptime Institute found average IT equipment loading at
~25 W/ft2
Benchmarking
IT Equipment Loading
(W/Sq.Ft. of electrically active floor space)
Current and Projected Load Intensity
0
20
40
60
80
100
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Facility
W/s
q.
ft.
Current Computer Load Projected Computer Load
BenchmarkingProjecting IT Load When Fully Loaded
H V A C (as a % o f to ta l load)
0%
10%
20%
30%
40%
50%
60%
1 2 3 4 5 6 7 8 9 10 11 12
D ata C en ter Id en tifier
% o
f to
tal
loa
d
Benchmarking
Data Center Benchmarking
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Facility
kW
/ t
on
Average 0.75
Benchmarking
Chiller Comparison
Total Average Efficiency kW/ton
0
0.5
1
1.5
2
2.5
3
Facility
kW
/to
n
Average 1.69
BenchmarkingTotal Chilled Water System Efficiency
0
20
40
60
80
100
0 20 40 60 80 100
Load Factor (%)
Eff
icie
nc
y (
%)
Benchmarking
UPS System Benchmarking
Standby Generation Loss• Several load sources
– Heaters– Battery chargers– Transfer switches– Fuel management systems
• Heaters alone (many operating hours) use more electricity than ever produced by the generator (few operating hours)
• Opportunity may be to reduce or eliminate heating, batteries, and chargers
Benchmarking
Standby Generator Heater
Benchmarking
No Impact on Reliability• Chiller and pumping efficiency
• Use of lighting controls
• Variable speed drives – pumps, chillers, fans
• Free cooling
• Improved UPS efficiency
BenchmarkingImproved Reliability and Energy Performance• Better match systems to their loads
• Improve humidity control and eliminate CRAC unit fighting
• Water side economizers
• Better control strategies – setpoints, cooling tower staging
• Better thermal stratification – high ceilings and properly sized underfloor
• Air management – delivering air where it’s needed
Benchmarking
General Recommendations• Benchmark to know where you stand
• Life-cycle cost analysis
• Facilities partnership with IT professionals
• Evaluate load spreading vs. compaction
Benchmarking
Available Benchmark Data?• Sources of other benchmark data?
• Please contact LBNL:
– Steve Greenberg: segreenberg@lbl.gov
– Bill Tschudi: wftschudi@lbl.gov
Benchmarking
Future Direction• Develop consensus on performance
benchmarks, collect data, quantify energy savings potential
• Incorporate other industry benchmark data
Power Dist98 - 99%
UPS88 - 92%
Power Supply68 - 72%
dc/dc78 - 85%
HVAC1,200W / 1 Ton (76%)
US Annual Energy Consumption of 30TW-h US Annual Energy Consumption of 30TW-h flows through this inefficient delivery pathflows through this inefficient delivery path
Data Center Power Delivery
Cost of Power DeliveryPower Path Efficiency
Power (kW)
MW-h
Cost
Load Cooling 3.1 113 $8,500
Loads Loads Systems (x100)
(not including dc/dc & ac/dc)
9.8
x 85% Dc/dc 2.1 109 $8,200$8,200
x 70% Power supply 5.1
x 90% UPS 1.9
x 98% Distribution 0.4
x 76% Delivery Cooling 3.0
Total = 40%Total = 40% Total 222 $16,700
Total efficiency Total efficiency ≈ 40%≈ 40%Cost of power delivery = $8,200 / 100Cost of power delivery = $8,200 / 100
Source: EPRI PEAC
Improvements in Cost of Power DeliveryPower Path Efficiency
Power (kW)
MW-h Cost ($k)
Load cooling 3.1 113 8.5
Loads Loads Systems (x100)
(not including dc/dc & ac/dc)
9.8
x 85% Dc/dc 2.1 109 109 6262
8.2 8.2 4.74.7
x 70% x 70% 85% 85% Power supply 5.1 5.1 2.1 2.1
x 90% x 90% 94% 94% UPS 1.9 1.9 0.9 0.9
x 98% Distribution 0.4 0.4 0.3 0.3
x 76% Delivery Cooling 3.0 3.0 1.7 1.7
Total = 40% 51% Total 222 222 175175
16.7 16.7 13.213.2
Annual cost reduced by $3,500 / 100Annual cost reduced by $3,500 / 100Source: EPRI PEAC
UPS Systems
UPS Activities• Determine the range of current UPS
efficiencies, highlight more efficient designs, and provide a means for comparing their total cost of ownership (TCO).
• Propose a new UPS labeling scheme that could be considered by Energy Star and other third -party efficiency labeling organizations.
• Conduct a scoping study to analyze the energy efficiency savings potential and performance of a complete DC power architecture for data centers.
Manufacturers data for efficiency versus load for current generation static and inertial UPS.
93.50%
92.80%
95.10%
93.50%
91.50%
92.00%
92.50%
93.00%
93.50%
94.00%
94.50%
95.00%
95.50%
Median 90th Percentile
100% Loading (Spec) 50% Loading (Spec)
Based on review of more than 100 static UPS models
UPS Systems
UPS Efficiency and Loading
32%
89%
64%
91%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Median 90thPercentile
Field UPS Loading (%)
Field UPS Efficiency (%)
Sample of 12 field measurements.
UPS Systems
UPS Measured Performance
Efficiency vs Load with High Efficiency Mode(HE) on and off
60646872768084889296
100
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percent of Full Load
Eff
icie
ncy
(%)
Non Linear Load High Efficiency Mode Non Linear Load Double Conversion Mode
Measured Result
Manufacturer Spec
On average, existing high efficiency modes can make a 4 to 5 % difference in UPS efficiency.
Source: EPRI PEAC
UPS SystemsMeasuring UPS Efficiency - “High Efficiency” Option
UPS SystemsAnalyzing UPS Performance in “High Efficiency” Option
High Efficiency Mode 30% sag 10 cycle
-400-300-200-100
0100200300400
0 50 100 150 200
Time (ms)
Vo
lts
Input Voltage Output Voltage
Double Conversion Mode 30% sag 30 cycle
-400-300-200-100
0100200300400
0 50 100 150 200
Time (ms)
Vo
lts
Input Voltage Output Voltage
In “high efficiency” mode, there can be one cycle
(16.6 msec for 60 Hz) of voltage deviation on UPS output.
Power supplies downstream of UPS can ride through this.
Source: EPRI PEAC
Quoted efficiencies are in the 96% range and higher; we will be measuring actual performance in field/lab
tests
Caterpillar PentadynePiller
UPS Systems
Research of Inertial Units
Efficiency and Reliability
Coordinating with International labeling effort addressing quality & efficiency.
Possible UPS efficiency labeling criteria
UPS Systems
Labeling
UPS SystemsLabeling will consider non-energy,reliability issues
Power Supply Activities • Measure efficiencies of current server
power supplies
• Field testing to document achievable energy savings
• Recommend new efficiency levels to Server System Infrastructure Initiative (SSI) for consideration
• Assess other PS saving opportunities in DC applications
Power Supplies Can Be Much More Efficient – Without Affecting Reliability Performance
• The nation’s 3.1 billion power supplies waste about 3 to 4% of the entire U.S. electricity bill
• Worst designs are 30 to 50% efficient
• Designs already exist in the market that can bring power supply efficiencies to the range of 75 to 93% with big non-energy benefits
• More efficient designs will be developed if there is incentive.
A consistent test protocol using a standard loading guideline & test
report format will allow more
visibility on power supply efficiency
Server Power Supply Efficiency Test Report
77%75%
Value Units100~127/200~240
Volts
3.2/1.6 Amps50-60 Hz
152.9 Watts
202.9 WattsNote: All measurements were taken with input voltage at 115 V nominal and 60 Hz.
IRMS PFA 12.0/6.0 5.0/22.0 3.3/13.0 -12.0/0.25 5.0 SB/1.00.56 0.92 7.9% 20% Light 59 12.0/0.95 4.98/3.47 3.30/2.06 - 4.99/1.00 41 68%
0.66 0.94 7.5% 25% 71 12.0/1.22 4.98/4.46 3.30/2.64 - 4.99/1.00 51 72%
1.15 0.98 5.7% 50% Typical 130 11.9/2.57 4.98/9.41 3.24/5.58 - 4.97/1.00 100 77%
1.69 0.99 4.9% 75% 192 12.0/3.93 4.93/14.39 3.20/8.52 - 4.97/1.00 150 78%
2.25 0.99 3.3% 100% Full 258 12.0/5.27 4.88/19.34 3.28/11.42 - 4.97/1.00 200 78%
Tested by EPRI PEAC Corporation,Knoxville, TN.
TYPICAL EFFICIENCY (50% Load):
Combined Max. Output Power on 5V and 3.3V
Load (%)
Rated Specifications
Input Voltage
Input CurrentInput Frequency
6/14/2004
Serial Number
Rated Output Power
Efficiency %
ITHD
(%)
Input Watts
Test Date
Model Serial Number
Input AC Current Waveform (ITHD = 5.7% at 50% Load)
TPS1U
DPS-20PB -118 B Rev 04BZT0237025302
YearType
AVERAGE EFFICIENCY :
These tests were conducted as a part of California Energy Commision initiative to improve the efficiency of the server power supplies used in the Data Centers through the Public Interest Energy Research (PIER) program.
Output Watts
DC Terminal Voltage (V)/ DC Load Current (A)Fraction of Load
Manufacturer2Delta Electronics
2002
Input and Output Power
Input Watts
Output Watts
0
50
100
150
200
250
300
20% 25% 50% 75% 100%Loading (% of Rated Output Power)
Po
wer
(W
atts
)
Efficiency of the Power Supply
40%
45%
50%
55%
60%
65%
70%
75%
80%
85%
90%
0% 25% 50% 75% 100% 125%Loading (% of Rated Output Power)
Eff
icie
ncy
(%
)
Efficiency %
Input AC Current and Voltage Waveforms
-200
-150
-100
-50
0
50
100
150
200
0 0.005 0.01 0.015
Time (s)
Vol
tage
(V
)
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
Cur
rent
(A
)
Voltage Current
Server Power Supply Efficiency Test Data: Current Market
48.6%
62.1%67.4%
72.5% 72.6% 70.9%62.2%
73.5%78.3% 80.0% 79.1% 77.8%
30%
40%
50%
60%
70%
80%
90%
100%
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Source: EPRI PEAC
95th Percentile
Median
% power supply loading% power supply loading
effi
cien
cyef
fici
ency
Importance of a Flat Power Supply Efficiency Curve
500W 1U Server Power Supply Efficiency Data
0
20
40
60
80
100
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
% Loading
Eff
icie
ncy
(%
)
Typical Loading
Range for Server PSU
More design focus on efficiency when More design focus on efficiency when lightly loaded is neededlightly loaded is needed
Goals of the Power Supply Task• Long term:
– Move the market towards widespread adoption of energy efficient PS in data centers
– Create an energy efficiency labeling program such as ENERGY-STAR® for server power supplies
30
131
32 32
72
41
86
27 32
020406080
100120140
AC
DC
Loss
es
DC
/DC
Loss
es
Fan
s
Driv
es
PC
I C
ards
Pro
cess
ors
Mem
ory
Chi
pset
Electric ity Use in a Server
Based on a typical dual processor 450W 2U Server; Approximately 160W out of 450W (35%) is losses in the power conversion process
(Source: Brian Griffith: INTEL)
Power Supplies in IT Equipment
Recommended Power Supply Efficiency
50%55%60%65%70%75%80%85%
0 100 200 300 400 500 600 700PSU Watt Rating
Power Supplies in IT Equipment
Electronic Load Banks
Yokogawa Digital Power
Meter
Fluke 41 Power Harmonic Analyzer
Power Supply Load Test Fixtures Server Power
Supply
Computer Interface
Server Power Supply EfficiencyLab Test Setup
Overall Computing Efficiency
Performance Metrics
AC Power Input Versus Percent CPU Time
0
25
50
75
100
125
150W
atts
0
20
40
60
80
100
120
% C
PU
Tim
e
WattsProc Time %
Dell Power Edge 2400 (Web/SQL Server)
Very Low Processor Activity…
…does not relate to very
low power consumption
Most of the time the GHz processor is doing activities that
can be done by a MHz processor but the input power consumption is not changing much
Performance Metrics -limited activity includes:• An assessment of:
– Server activity profile based on application/server type
– Correlation of server activity and power consumption
• Work with Intel, AMD, IBM, HP, and potentially others to reach consensus on metrics for some applications.
• Develop efficiency guidelines based on performance metrics
Demonstrations
LBNL’s Role in Demonstrations• Scoping demonstrations of technologies
or strategies to improve energy efficiency in high-tech buildings
• Showcase new/emerging or under-utilized technologies or approaches
Currently Planned Demonstrations
• Heat removal from servers without fans
• DC powering rack of servers
• Air management improvements (PG&E)
Demonstrations
Conclusion• Many strategies to improve energy
performance in a data center can be implemented with no impact on reliability – in fact, many will actually improve reliability and lower capital cost.
• Major industry firms are interested in supporting efficiency (and reliability) improvement.
• If you want more efficient data centers – ask for them.
Thank You• Questions?
• Bill Tschudi, Principal InvestigatorLawrence Berkeley National Lab510.495.2417wftschudi@lbl.gov
• http://hightech.lbl.gov
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