ENERGY STAR® Program Requirements
Product Specification for
Computers
Draft 2 Test Method
Rev. July-2019

1

1 OVERVIEW

2
3

The following test method shall be used for determining product compliance with requirements in the
ENERGY STAR Specification for Computers.

4

2 APPLICABILITY

56

ENERGY STAR test requirements are dependent upon the feature set of the product under evaluation.
The following guidelines shall be used to determine the applicability of each section of this document:

7
8▪

The procedure in Section 6 shall be conducted on all eligible products that are covered under thescope as defined in Section 2 of the ENERGY STAR Eligibility Criteria for Computers.

9▪

The procedure in Section 7 shall be conducted only on eligible Workstation Computer products.

10

3 DEFINITIONS

11
12

Unless otherwise specified, all terms used in this document are consistent with the definitions in the
ENERGY STAR Specification for Computers.

13

4 TEST SETUP

14

4.1 Test Setup and Instrumentation

15
16
17
18
19

Test setup and instrumentation for all portions of this procedure shall be in accordance with therequirements of International Electrotechnical Commission (IEC) standard, IEC 62301, “Household
Electrical Appliances – Measurement of Standby Power” Edition 2.0, 2011-01, Section 4, “General
Conditions for Measurements”, unless otherwise noted in this document. In the event of conflicting
requirements, the ENERGY STAR test method shall take precedence.

20
21A) Input Power: Products intended to be powered from alternating current (ac) mains shall be connected
to a voltage source appropriate for the intended market, as specified in Table 1 and Table 2.

ENERGY STAR Program Requirements for Computers – Draft 2 Test Method (Rev. July-2019)

Page 1 of 10

22
23

Table 1: Input Power Requirements for Products with
Nameplate Rated Power Less Than or Equal to 1500 watts (W)Voltage

VoltageTolerance

Maximum
Total
Harmonic
Distortion

Frequency

Frequency
Tolerance

North America, Taiwan

115 volts(V) ac+/- 1.0 %2.0 %60 hertz(Hz)+/- 1.0 %Europe, Australia, New Zealand

230 V ac+/- 1.0 %

2.0 %

50 Hz

+/- 1.0 %Japan

100 V ac+/- 1.0 %2.0 %50 Hz or
60 Hz+/- 1.0 %Market24
25

Table 2: Input Power Requirements for Products with
Nameplate Rated Power Greater Than 1500 W

Voltage

VoltageTolerance

Maximum
Total
Harmonic
Distortion

Frequency

Frequency
Tolerance

North America, Taiwan

115 V ac+/- 4.0 %

5.0 %

60 Hz

+/- 1.0 %Europe, Australia, New Zealand

230 V ac+/- 4.0 %

5.0 %

50 Hz

+/- 1.0 %Japan

100 V ac+/- 4.0 %5.0 %50 Hz or
60 Hz+/- 1.0 %Market26
27B) Ambient Temperature: Ambient temperature shall remain between 18 C and 28 C, inclusive, for theduration of the test.

2829C) Relative Humidity: Relative humidity shall remain between 10% and 80%, inclusive, for the duration of
the test.

30D) Light Measuring Device (LMD): All LMDs shall meet the following specifications:311) Accuracy: ± 2% (± 2 digits) of the digitally displayed value; and

322) Acceptance Angle: 3 degrees or less.

33
34
35
36
37
38

The overall tolerance of LMDs is found by taking the absolute sum of 2%of the targeted screen
luminance and a 2 digit tolerance of the displayed value’s least significant digit. For example, if thescreen luminance value is 90 candela per meter squared (cd/m2) and the LMD’s least significant digit
is a tenth of one cd/m2, 2% of 90 cd/m2 would be 1.8 cd/m2 and a 2 digit tolerance of the leastsignificant digit would be 0.2 cd/m2. Thus, the displayed value would need to be 90 ± 2 cd/m2 (1.8
cd/m2 + 0.2 cd/m2).

39
40

Note: The term “nit” is sometimes used instead of the official SI unit cd/m2. One nit is equivalent to
one cd/m2.

4142E) Power Meter: Power meters shall possess the following attributes:
1) Crest Factor:

43a) An available current crest factor of 3 or more at its rated range value; and44b) A bound on the current range of 10 milliamperes (mA) or less.

452) Minimum Frequency Response: 3.0 kilo-hertz (kHz)46

3) Minimum Resolution:

47a) 0.01 W for measurement values less than 10 W;

ENERGY STAR Program Requirements for Computers – Draft 2 Test Method (Rev. July-2019)

Page 2 of 10

48b) 0.1 W for measurement values from 10 W to 100 W; and49c) 1.0 W for measurement values greater than 100 W.

50514) Measurement Accuracy: Measurement uncertainty as introduced by the instrument that measures
the input power to the unit under test (UUT), including any external shunts.

5253a) Power measurements with a value greater than or equal to 0.5 W shall be made with anuncertainty of less than or equal to 2% at the 95% confidence level.

5455b) Power measurements with a value less than 0.5 W shall be made with an uncertainty of lessthan or equal to 0.01 W at the 95% confidence level.

56

5 TEST CONDUCT

57

5.1 Guidance for Implementation of IEC 62623

58
59
60

The Test Conduct shall be carried out according to the requirements in IEC 62623, “Desktop andNotebook Computers – Measurement of Energy Consumption” Edition 1.0, 2012-10 (IEC 62623 Ed. 1.0,
2012-10) reference with the following guidance.

61
62
63
64
65
66

A) Thin Clients and Workstations shall be configured in a manner identical to Desktops (non-integrated)
unless otherwise specified. Slates/Tablets shall be configured in a manner identical to Notebooks
unless otherwise specified. Portable All-In-One Computers shall be configured in a manner identicalto Integrated Desktops unless otherwise specified.
1) Thin Clients shall run intended terminal/remote connection software during all tests.

67B) Wake on LAN (WoL) settings shall be in as shipped condition for testing Sleep Mode and Off Mode.

6869C) For models that do not offer a Sleep Mode enabled by default, Section 6.2 shall measure power in thelowest-latency user-activated mode or state that preserves machine state and is enabled by default.

70711) If no such state separate from Long Idle State or Off Mode exists, the measurement in
Section 6.2 shall be skipped.

72
73
74
75

D) For Long Idle Mode Testing (Section 6.3), the UUT shall be allowed no more than 20 minutes fromthe point of ceased user input before measurements must be started. If any default settings cause the
UUT to enter Long Idle after 20 minutes, begin taking measurements when the UUT has reached the
20 minute mark. Display sleep settings shall be set to default for Long Idle Mode Testing.

76
77
78
79
80
81
82

E) For Alternative Low Power Mode Testing (Section 6.3), the UUT shall be allowed no more than 20
minutes from the point of ceased user input before measurements must be started. If any default
settings cause the UUT to enter the Alternative Low Mode after 20 minutes, begin taking
measurements when the UUT has reached the 20 minute mark. Display sleep settings shall be set todefault for Alternative Low Power Mode Testing. When conducting the test in section 6.3, replace all
instances of “Long Idle Mode” with “Alternative Low Power Mode.”, and apply the definition of
Alternative Low Power Mode from the ENERGY STAR Specification for Computers.

83
84
85
86
87

F) For Short Idle Mode Testing (Section 6.4), the UUT shall be allowed no more than five minutes fromthe point of ceased user input before measurements must be taken. Display sleep settings shall bedisabled for Short Idle Mode Testing. If any other default settings cause the UUT to exit Short Idle
during the measurement time, extend the settings so that the UUT remains in short idle for theduration of the measurement.

88
89
90
91

extend the short idle test long enough to capture the energy consumption over one or more complete
cycles. The extended test shall be conducted by keeping the unit in short idle through minimal user
input such as moving the mouse or pressing a key that does not perform any action (e.g. shift, ctrl,
tab, etc). The UUT must remain in short idle during the entire time of the extended test.

ENERGY STAR Program Requirements for Computers – Draft 2 Test Method (Rev. July-2019)

Page 3 of 10

92
93
94
95
96

Note: DOE continued to seek feedback on this topic from stakeholders present at the June 18, 2019
stakeholder meeting. Stakeholders recommended an extended short idle test be performed without user
input. However, a lack of periodic user input makes it difficult to ensure that the system remains in shortidle mode throughout the duration of the test. Accordingly, DOE intends to retain the approach ofextending the short idle test with minimal user feedback as proposed in Draft 1.

97
98
99
100
101
102

In Version 7.1, DOE also allowed a temporary solution of disabling the battery via software when theexisting short idle test would not adequately capture a systems cyclical charging behavior, provided thatthe software disconnect solution could be verified by comparing the results to an extended short idle test
measured over one or more complete cyclical patterns. With the implementation of the extended shortidle test as the test measurement, the interim solution of disabling the battery is no longer required andhas been removed.

103
104
105

G) Desktops, Integrated Desktops, Notebook Computers, Portable All-In-One Computers, andSlates/Tablets shall be tested for Idle, Sleep, and Off Mode with Full Network Connectivity(“Proxying”) features using the as shipped setting.

106
107

H) Celluar network connections shall be disabled for testing. Additionally, Bluetooth should be left asshipped.

108
109
110
111

I)

112
113
114

Note: DOE did not receive any comments on its proposal to extend testing in long idle, alternative low
power mode, sleep mode and off mode as part of Draft 1. DOE is therefore retaining these provisions for
Version 8.0.

115
116
117

J) Any secondary storage drive may have the power management features enabled during short idle aslong as those power management features are enabled by default. A secondary storage drive refers
to any drive that does not contain the operating system software.

118
119

5.2 Preparing Display Luminance of Notebooks, Integrated Desktops,
Slates/Tablets and Portable All-In-One Computers

120
121
122

A) Before performing any tests, disable display dimming, display Sleep Mode, Computer Sleep Mode,and automatic brightness control (ABC) in the Computer settings. Document all settings that werechanged from the default configuration.

123
124

1) If ABC cannot be disabled, position a light source such that at least 300 lux directly enters theABC sensor.

125
126
127
128

B) Display the three vertical bar video signal as defined in section 3.2.1.3 of IEC 60107-1, “Methods ofmeasurement on receivers for television broadcast transmissions – Part 1: General conditions –Measurements at radio and video frequencies” Edition 3.0, 1997 (IEC 60107-1 Ed. 3.0, 1997). The
three bar image shall be configured using the default image display application.

129
130

C) Devices with a cold cathode fluorescent lamp (CCFL) backlight shall warm-up for at least 30 minutes.
All other displays shall warm-up for at least 5 minutes.

131D) With the LMD, measure the luminance in the center of the display.

132
133
134
135

E) Calibrate the UUT display brightness to the closest brightness setting that is at least 90 cd/m2 for
Notebook Computers, at least 150 cd/m2 for Integrated Desktop Computers, Portable All-In-One
Computers and Slates/Tablets. If the UUT’s brightest setting cannot achieve the specified brightness,then set the UUT display to the brightest setting.

If the UUT exhibits any cycling behavior and the normal measurement time would not capture one ormore complete cycles, measure the long idle, alternative low power mode, sleep mode, and off modemeasurement using an extended measurement capturing one or more full cycles per IEC 62301,
section B.2.3.

ENERGY STAR Program Requirements for Computers – Draft 2 Test Method (Rev. July-2019)

Page 4 of 10

136
137
138
139
140

F) The display shall be configured with the ENERGY STAR test image, which can be found here1. For
Desktops, Integrated Desktops, Notebook Computers and Portable All-In-One Computers it may be
set as the “desktop background” (wallpaper) or shown via an image display application. The image
shall be scaled to completely fill the display area. For Slates/Tablets, the display shall be configured
with the default image display application.

141
142
143
144
145
146

G) Optional setting for units with multiple integrated displays. Configure all displays in the same way
using the previous steps. The displays do not have to be configured sequentially (i.e. warmup times
can be done simultaneously for all displays). For notebook computers, all displays must be set to theclosest brightness setting that is at least 90 cd/m2 for every display. For Integrated Desktop
Computers, Portable All-In-One Computers and Slates/Tablets, all displays must be set to the closest
brightness setting that is at least 150 cd/m2 for every display.

147
148

H) For all testing specified in Section 6, the UUT shall not be rebooted or restarted until after the power
measurements for Long Idle Mode and Short Idle Mode tests are taken.

149
150

I)

151

5.3 Preparing External Displays for Desktops

152
153
154
155

A) Display Connection Priority

Slate/Tablet and Portable All-In-One Computers shall be tested with a docking station only if it isshipped with the product and is the only way to power the device mains.

If the UUT and external monitor support multiple signal interfaces, the UUT shall be tested with thefirst available interface from the list below:
External Display Connection Priorityi.

Thunderbolt

ii.

DisplayPortiii. USB-C
iv. HDMIv.

DVI

vi. VGA
156
157
158
159

Note: DOE has added a display connection priority to improve testing repeatability and uniformity. The
proposed priority aligns with the requirements in the ENERGY STAR Displays Specification, which isused to test computer monitors. DOE requests feedback on the priority order and whether there are otherfactors that should be considered in selecting a display connection when multiple interfaces exist.

160B) Display Resolution:1

https://www.energystar.gov/ia/partners/images/ComputerTestingImage.bmp

ENERGY STAR Program Requirements for Computers – Draft 2 Test Method (Rev. July-2019)

Page 5 of 10

161
162
163

Note: There currently does not exist a display resolution requirement for systems that require an external
display and one is not shipped with the unit. Similarly, there is no test parameter that requires systems to
be tested at a particular resolution.

164
165
166
167

At the June 18, 2019, stakeholder meeting, DOE presented the idea of testing systems with an external
display that supports 4K resolution. Stakeholders present at the meeting communicated that the
ENERGY STAR specification is based strictly on systems that did not utilize a 4K display. As such,
updating the test method to test with such a display would be inconsistent with the specification.

168
169
170

DOE continues to request feedback on whether such a resolution parameter would improve therepeatability of the test method and, if so, what that resolution should be. EPA and DOE may consider
updating a future specification and test method to reflect a 4K resolution display.

171

6 TEST PROCEDURES FOR ALL PRODUCTS

172

6.1 UUT Preparation

173
174

UUT preparation shall be performed according to IEC 62623, Ed.1.0, 2012-10, Section 5.2: Test Setup;with the additional guidance in Section 5 of this document.

175

6.2 Sleep Mode Testing

176
177

Sleep Mode power shall be measured according to IEC 62623, Ed.1.0, 2012-10, Section 5.3.3:
Measuring Sleep Mode; with the additional guidance in Section 5 of this document.

178

6.3 Long Idle Mode Testing

179
180

Long Idle Mode power shall be measured according to IEC 62623, Ed.1.0, 2012-10, Section 5.3.4:
Measuring Long Idle Mode; with the additional guidance in Section 5 of this document.

181

6.4 Short Idle Mode Testing

182
183

Short Idle Mode power shall be measured according to IEC 62623, Ed.1.0, 2012-10, Section 5.3.5:
Measuring Short Idle Mode; with the additional guidance in Section 5 of this document.

184

6.5 Off Mode Testing
Off Mode power shall be measured according to IEC 62623, Ed.1.0, 2012-10, Section 5.3.2: Measuring
Off Mode; with the additional guidance in Section 5 of this document.

185

6.6 Additional Testing For Reporting

186
187

For Notebook Computers, repeat the Short Idle test with the display brightness set to the closest settingthat is at least 150 cd/m2 for all displays.

188

6.7 Sleep to Wake Latency Test

189
190
191

Note: With this Draft, EPA has proposed that compliance with the Sleep to Wake Latency requirement be
self-certified. The value will not be confirmed through the ENERGY STAR certification process. As such,
DOE is removing the Sleep to Wake Latency test.

192

7 TEST PROCEDURES FOR WORKSTATIONS

193

7.1 Maximum Power Test

ENERGY STAR Program Requirements for Computers – Draft 2 Test Method (Rev. July-2019)

Page 6 of 10

194
195
196
197
198
199

The maximum power for Workstations is found by the simultaneous operation of two industry standard
benchmarks: Linpack to stress the core system (e.g., processor, memory, etc.) and SPECviewperf®
(latest available version for the UUT) to stress the system’s Graphics Processing Unit (GPU). This test
shall be repeated three times on the same UUT, and all three measurements shall fall within a ± 2%
tolerance relative to the average of the three measured maximum power values. The average powershould be used for qualification and/or TEC calculations.

200
201
202
203

Note: Workstations may certify configurations using Microsoft Windows® OS as a proxy for Linux for the
maximum power test, as SPEC does not currently support a version of SPECviewperf® capable ofrunning on the Linux OS.

204
205
206

Additional information on these benchmarks, including free downloads, can be found at the following
locations as specified in Table 3.

207

208

Table 3: Benchmark Information for Maximum Power Test

BenchmarkWebsite

Linpack

http://www.netlib.org/linpack/

SPECviewperf

http://www.spec.org/benchmarks.html#gpc

A) UUT Preparation:

209
210
211
212

1) Connect a power meter capable of measuring true power to an ac line voltage source set to theappropriate voltage/frequency combination for the test. The meter shall have all the attributes
listed in Section 4.1 E). The meter shall also store and output the maximum power measurement
reached during the test or be capable of another method of determining maximum power.

213
214

2) Plug the UUT into the measurement power outlet on the meter. No power strips or uninterruptible
power supply (UPS) units shall be connected between the meter and the UUT.

215

3) Record the ac voltage.

216
217

4) Boot the UUT and, if not already installed, install Linpack and SPECviewperf as indicated on theabove Websites.

218
219

5) Set Linpack with all the defaults for the given architecture of the UUT and set the appropriate
array size “n” for maximizing power draw during the test.

220
221
222

6) Ensure all technical guidelines relevant to running the benchmark set by the Standard
Performance Evaluation Corporation (SPEC) organization for running SPECviewperf have been
met.

223
224

7) For additional information regarding Linpack setup, see Section 9.1 Typical Linpack Starting
Parameters.

225B) Maximum Power Testing:

226
227

1) Set the meter to begin accumulating true power values at a rate greater than or equal to one
reading per second, and begin taking measurements.

228
229

2) Run SPECviewperf and as many simultaneous instances of Linpack as needed to fully stress thesystem. Recommended setup information can be found in Section 9.1 C).

230
231

3) Accumulate power values until SPECviewperf and all Linpack instances have completed running.
Record the maximum power value attained during the test.

2324) The following data shall also be recorded:

233a) Value of “n” (the array size) used for Linpack;
ENERGY STAR Program Requirements for Computers – Draft 2 Test Method (Rev. July-2019)

Page 7 of 10

234b) Number of simultaneous copies of Linpack run during the test;

235c) Version of SPECviewperf run for test;

236d) All compiler optimizations used in compiling Linpack and SPECviewperf; and

237
238
239

e) A precompiled binary for end users to download and run both SPECviewperf and Linpack.
These can be distributed either through a centralized standards body such as SPEC, by theoriginal equipment manufacturer (OEM), or by a related third party.

240

7.2 Benchmark Test

241
242
243
244

The benchmark test shall be performed by running both benchmarks listed below separately. The UUT
shall be rebooted before testing with each benchmark. Additional information on these benchmarks,
including downloads, can be found at the following locations specified in Table 4. All testing shall be
performed with the latest available version of the benchmarks.

245

246

Table 4: Information for Benchmark Testing

BenchmarkWebsite

Linpack

http://www.netlib.org/linpack/

SPECviewperf

http://www.spec.org/benchmarks.html#gpc

A) UUT Preparation:

2471) The UUT shall be setup identical to Step 1) through Step 4) of Section 7.1 A)248

2) If not already installed, install the benchmark as indicated on the websites listed in Table 4.

2493) Configure the benchmark as specified in Section 7.2 B).

250
251

4) Time Measurement: Time measurements may be performed with a standard stopwatch or othertime keeping device with a resolution of at least 1 second.

252
253

B) Benchmark Configurations:1) Linpack

254
255

a) Configure the Linpack settings identically to the maximum power workstation test (e.g. Follow
Step 5) and Step 7) of Section 7.1 A)).

256
257
258

b) Run as many simultaneous instances of Linpack as needed to fully stress the system.
Recommended settings would be to set the number of simultaneous instances of Linpackequal to the number of logical and/or physical CPU cores of the system.

259
260
261
262

2) SPECviewperfa) Configure the settings identically to the maximum power workstation test (e.g. Follow Step 6)of Section 7.1 A)).
C) Benchmark Testing:

263
264

1) Set the meter to begin accumulating true power values at a rate of greater than or equal to one
reading per second and begin power and time measurement.

2652) Execute the benchmark.

266
267

3) Stop time measurement and accumulate power values for the entire duration of the benchmark
run.

268

4) The following data shall be reported:

269a) Linpack

ENERGY STAR Program Requirements for Computers – Draft 2 Test Method (Rev. July-2019)

Page 8 of 10

270

i.

Value of “n” (the array size) used for Linpack;

271

ii.

Number of instances of Linpack simultaneously run on the system;272

iii. All compiler options used in compiling Linpack;273

iv. Energy consumed over the duration of the test; and

274
275
276

v.

277

Linpack output file in text format which contains system performance in floating point
operations per second (Flops) in addition to other Linpack parameters (e.g. number oftests, problem size, etc.).

b) SPECviewperf

278

i.

Version of SPECviewperf used;

279

ii.

All compiler optimizations used in compiling SPECviewperf;

280

iii. Duration of the test;

281

iv. Energy consumed over the duration of the test; and

282

v.

283

8 REFERENCES

284A) IEC 62301 Edition 2.0 2011-01, Household electrical appliances – Measurement of standby power.

285
286

B) IEC 60107-1 Edition 3.0 1197-04, Methods of measurement on receivers for television broadcast
transmissions – Part 1: General Considerations – Measurements at radio and video frequencies.

287
288

C) IEC 62623 Edition 1.0 2012-10, Desktop and notebook computers – Measurement of energy
consumption

289

9 APPENDIX: BENCHMARK PARAMETERS

290

9.1 Typical Linpack Starting Parameters

291
292
293
294

Below are some typical starting values for the use of Linpack for testing Workstations. These values arestarting points and not meant to be binding. The tester is free to use the settings most advantageous totheir UUT. Platform and Operating System (OS) will have a significant impact on the applicability of thesestarting values. The below assumes Linux as the test OS.

295A) Number of equations (problem size): See Equation.

296B) Leading dimensions of array: See Equation.

297
298
299
300
301
302
303
304
305
306
307
308
309
310

All files and folders present in the Result folder of SPECviewperf suite shall be reported.

The matrix size (the combination of number of equations and leading dimensions of array) should be
the maximum size that will fit in the Random Access Memory (RAM) on the machine.
This AWK script will calculate matrix size on a Linux machine:awk 'BEGIN {
printf "Maximum matrix dimension that will fit in RAM on this machine: "}/^MemTotal:/ {print int(sqrt(($2*1000)/8)/1000) "K"}' /proc/meminfo
Use the output of this to determine what matrix size to input for both the "Number of equations" and"Leading dimensions of array" inputs. The “Number of equations” will be equal to the printed output.
The “Leading dimensions of the array” will be the output rounded up to the nearest multiple of eight.

ENERGY STAR Program Requirements for Computers – Draft 2 Test Method (Rev. July-2019)

Page 9 of 10

311
312

313

This calculation can be most easily calculated by taking the memory size, in bytes, of the UUT(denoted as m) and substituting m in Equation 1.

m 1000
8
1000

314

Equation 1: Memory Size Calculation

315
316
317

C) Number of trials: c - 1 where c equals the number of logical and/or physical CPU cores of the system.
The tester needs to determine which is more advantageous for the unit. The -1 leaves one core openfor use by SPECviewperf.

318
319

D) Data alignment value: Typically four with Linux systems. The best value to use is the page size
boundary of the OS.

ENERGY STAR Program Requirements for Computers – Draft 2 Test Method (Rev. July-2019)

Page 10 of 10