ISO/IEC 30134-2:2016
(Main)Information technology — Data centres — Key performance indicators — Part 2: Power usage effectiveness (PUE)
Information technology — Data centres — Key performance indicators — Part 2: Power usage effectiveness (PUE)
ISO/IEC 30134-2:2016 a) defines the power usage effectiveness (PUE) of a data centre, b) introduces PUE measurement categories, c) describes the relationship of this KPI to a data centre's infrastructure, information technology equipment and information technology operations, d) defines the measurement, the calculation and the reporting of the parameter, e) provides information on the correct interpretation of the PUE. PUE derivatives are described in Annex D.
Technologies de l'information — Centres de données — Indicateurs de performance clés — Partie 2: Efficacité dans l'utilisation de la puissance (PUE)
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INTERNATIONAL ISO/IEC
STANDARD 30134-2
First edition
2016-04-15
Information technology — Data
centres — Key performance
indicators —
Part 2:
Power usage effectiveness (PUE)
Technologies de l’information — Centres de données — Indicateurs de
performance clés —
Partie 2: Efficacité dans l’utilisation de la puissance (PUE)
Reference number
ISO/IEC 30134-2:2016(E)
©
ISO/IEC 2016
---------------------- Page: 1 ----------------------
ISO/IEC 30134-2:2016(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO/IEC 2016 – All rights reserved
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ISO/IEC 30134-2:2016(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, abbreviated terms and symbols . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 2
3.3 Symbols . 2
4 Applicable areas of the data centre . 3
5 Determination of power usage effectiveness (PUE) . 3
6 Measurement of power usage effectiveness . 4
6.1 Measuring energy consumption . 4
6.1.1 General. 4
6.1.2 Measurement period and frequency . 4
6.1.3 Meter and measurement requirements . 4
6.2 Categories of power usage effectiveness . 5
6.2.1 General. 5
6.2.2 Category 1 (PUE ) — Basic resolution . 5
1
6.2.3 Category 2 (PUE ) — Intermediate resolution. 5
2
6.2.4 Category 3 (PUE ) — Advanced resolution . 6
3
6.2.5 Measurement placement . 6
7 Reporting of power usage effectiveness . 6
7.1 Requirements . 6
7.1.1 Standard construct for communicating PUE data . 6
7.1.2 Example of reporting PUE values . 6
7.1.3 Data for public reporting of PUE . 6
7.2 Recommendations . 7
7.2.1 Use of PUE category . 7
7.2.2 Trend tracking data . 7
Annex A (normative) Energy measurements. 9
Annex B (normative) Calculation of PUE using various energy supplies .11
Annex C (normative) PUE derivatives .16
Annex D (informative) Interpretation of PUE and its derivatives .23
Bibliography .25
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ISO/IEC 30134-2:2016(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical
activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international
organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the
work. In the field of information technology, ISO and IEC have established a joint technical committee,
ISO/IEC JTC 1.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for
the different types of document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject
of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent
rights. Details of any patent rights identified during the development of the document will be in the
Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical
Barriers to Trade (TBT), see the following URL: Foreword — Supplementary information.
The committee responsible for this document is ISO/IEC JTC 1, Information technology, Subcommittee
SC 39, Sustainability for and by Information Technology.
ISO/IEC 30134 consists of the following parts, under the general title Information technology — Data
centres — Key performance indicators:
— Part 1: Overview and general requirements
— Part 2: Power usage effectiveness (PUE)
— Part 3: Renewable energy factor (REF)
The following parts are under preparation:
— Part 4: IT Equipment Energy Efficiency for Servers (ITEEsv)
— Part 5: IT Equipment Utilization for Servers (ITEUsv)
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ISO/IEC 30134-2:2016(E)
Introduction
The global economy is now reliant on information and communication technologies and the associated
generation, transmission, dissemination, computation and storage of digital data. All markets have
experienced exponential growth in that data, for social, educational and business sectors and, while the
internet backbone carries the traffic there are a wide variety of data centres at nodes and hubs within
both private enterprise and shared/collocation facilities.
The historical data generation growth rate exceeds the capacity growth rate of the information and
communications technology hardware and, with less than half (in 2014) of the world’s population
having access to an internet connection, that growth in data can only accelerate. In addition, with
many governments having “digital agendas” to provide both citizens and businesses with ever faster
broadband access, the very increase in network speed and capacity will, by itself, generate ever more
usage (Jevons Paradox). Data generation and the consequential increase in data manipulation and
storage are directly linked to increasing power consumption.
With this background, it is clear that data centre growth, and power consumption in particular, is an
inevitable consequence and that growth will demand increasing power consumption despite the most
stringent energy efficiency strategies. This makes the need for key performance indicators (KPIs)
that cover the effective use of resources (including but not limited to energy) and the reduction of CO
2
emissions essential.
Within the ISO/IEC 30134 series, the term “resource usage effectiveness” is more generally used for KPIs
in preference to “resource usage efficiency”, which is restricted to situations where the input and output
parameters used to define the KPI have the same units.
In order to determine the overall resource effectiveness or efficiency of a data centre, a holistic suite
of metrics is required. This part of ISO/IEC 30134 specifies power usage effectiveness (PUE), which
has become a popular metric to determine the efficient utilization and distribution of energy resources
within a data centre.
NOTE It is recognized that the term “efficiency” is to be employed for PUE but “effectiveness” provides
continuity with earlier market recognition of the term.
This part of ISO/IEC 30134 belongs to a series of standards for such KPIs and has been produced in
accordance with ISO/IEC 30134-1, which defines common requirements for a holistic suite of KPIs for
data centre resource usage effectiveness or efficiency.
The ISO/IEC 30134 series does not specify limits or targets for any KPI and does not describe or imply,
unless specifically stated, any form of aggregation of individual KPIs into a combined nor an overall KPI
for data centre resource usage effectiveness or efficiency.
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INTERNATIONAL STANDARD ISO/IEC 30134-2:2016(E)
Information technology — Data centres — Key
performance indicators —
Part 2:
Power usage effectiveness (PUE)
1 Scope
This part of ISO/IEC 30134 specifies the power usage effectiveness (PUE) as a key performance
indicator (KPI) to quantify the efficient use of energy in the form of electricity.
This part of ISO/IEC 30134
a) defines the power usage effectiveness (PUE) of a data centre,
b) introduces PUE measurement categories,
c) describes the relationship of this KPI to a data centre’s infrastructure, information technology
equipment and information technology operations,
d) defines the measurement, the calculation and the reporting of the parameter,
e) provides information on the correct interpretation of the PUE.
PUE derivatives are described in Annex D.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO/IEC 30134-1:2016, Information technology — Data centres — Key performance indicators — Part 1:
Overview and general requirements
3 Terms, definitions, abbreviated terms and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/IEC 30134-1 and the
following apply.
3.1.1
information technology (IT) equipment energy consumption
energy consumed, measured in kilowatt-hour (kWh), by equipment that is used to store, process, and
transport data within the computer room, telecommunication room and control room spaces
Note 1 to entry: Examples are servers, storage equipment, and telecommunications equipment.
3.1.2
power distribution unit
PDU
equipment that allocates or partitions power for other energy consuming equipment
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ISO/IEC 30134-2:2016(E)
3.1.3
power usage effectiveness
PUE
ratio of the data centre total energy consumption to information technology equipment energy
consumption, calculated, measured or assessed across the same period
Note 1 to entry: Sometimes the inverse value of PUE, referred to as Data Centre Infrastructure Efficiency (DCiE),
is used.
3.1.4
partial power usage effectiveness
pPUE
derivative of PUE, which is the ratio of the total energy consumption within a defined boundary to the
information technology equipment energy consumption
3.1.5
designed power usage effectiveness
dPUE
derivative of PUE, which is a projected PUE determined by the design targets of the data centre
3.1.6
interim power usage effectiveness
iPUE
derivative of PUE, which is measured over a specified time other than a year
3.1.7
total data centre energy consumption
total energy consumption for all energy types serving the data centre, measured in kWh at its boundary
Note 1 to entry: Energy measured with energy metering devices at the boundary of the data centre or points of
generation within the boundary.
Note 2 to entry: This includes electricity, natural gas and district utilities such as supplied chilled water or
condenser water.
3.2 Abbreviated terms
For the purposes of this document, the abbreviated terms given in ISO/IEC 30134-1 and the
following apply:
CRAC computer room air conditioner units
CRAH computer room air handler units
dPUE designed power usage effectiveness
DX direct expansion
iPUE interim power usage effectiveness
PDU power distribution unit
pPUE partial power usage effectiveness
r.m.s. root mean square
ROI return on investment
UPS uninterruptible power supply
3.3 Symbols
For the purposes of this document, the following symbols apply:
E total data centre energy consumption (annual) in kWh
DC
E IT equipment energy consumption (annual) in kWh
IT
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ISO/IEC 30134-2:2016(E)
4 Applicable areas of the data centre
Power usage effectiveness (PUE) as specified in this part of ISO/IEC 30134
— is associated with the data centre infrastructure within its boundaries only,
— describes the infrastructure’s energy efficiency relative to facilities with given environmental
conditions, IT load characteristics, availability requirements, maintenance, and security
requirement, and
— illustrates the energy allocation of a data centre.
When viewed in the proper context, PUE provides effective guidance and useful insight into the design
of efficient power and cooling architectures, the deployment of equipment within those architectures,
and the operation of that equipment.
PUE provides a means to determine
— opportunities for the improvement of the operational efficiency of a data centre,
— the improvement of the designs and processes of a data centre over time, and
— a design target or goal for new data centres across the anticipated IT load range.
PUE does not take into account the
— energy efficiency of the IT load, its utilization or productivity,
— efficiency of on-site electricity generation,
— efficiency of other resources such as human resource, space or water, and
— use of renewable energy resources or accounts for re-use of waste by-products (such as heat).
PUE is not a
— data centre productivity metric, and
— standalone, comprehensive resource efficiency metric.
Derivatives of PUE which are useful in certain circumstances as described in Annex C. PUE should not
be used to compare different data centres.
5 Determination of power usage effectiveness (PUE)
PUE is defined using Formula (1):
E
DC
PUE= (1)
E
IT
where
E is the total data centre energy consumption (annual), in kWh;
DC
E is the IT equipment energy consumption (annual), in kWh.
IT
By definition, the calculated PUE is always greater than 1.
Where the only energy source is from the electrical utility, then E is determined by the location of the
DC
utility meter. PUE may be applied in mixed use buildings that allow of the differentiation between the
energy used for the data centre and that for other functions. Alternatively, the derivative partial PUE
(pPUE) may be applied (see Annex C).
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ISO/IEC 30134-2:2016(E)
E includes, but is not limited to,
IT
— IT equipment (e.g. storage, processing and transport equipment), and
— supplemental equipment (e.g. keyboard/video/mouse (KVM) switches, monitors, and
workstations/laptops used to monitor, manage, and/or control the data centre).
E includes E plus all the energy that is consumed to support the following infrastructures:
DC IT
— power delivery [e.g. UPS systems, switchgear, generators, power distribution units (PDUs), batteries,
distribution losses external to the IT equipment, etc.];
— cooling system [e.g. chillers, cooling towers, pumps, computer room air handling units (CRAHs),
computer room air conditioning units (CRACs), direct expansion air handler (DX) units, etc.];
— others (e.g. data centre lighting, elevator, security system and fire detection/suppression system).
6 Measurement of power usage effectiveness
6.1 Measuring energy consumption
6.1.1 General
In order to calculate PUE, it is necessary to measure E and E . This is not a trivial task, especially
DC IT
within existing data centres which may require the installation of instrumentation to collect the data.
NOTE Although measurement of E and E are adequate to calculate PUE for the defined equipment and
DC IT
supporting infrastructure, more monitoring data of logical subsets is necessary to assess areas for potential
improvements and to evaluate the resulting improvements to PUE across the data centre.
6.1.2 Measurement period and frequency
The calculation of PUE requires the recording and documenting of E and E over a coincident period
DC IT
of 12 months. This part of ISO/IEC 30134 does not specify the frequency of measurements of E and
DC
E , since PUE is calculated on an annual timeframe. However, the frequency of measurement employed
IT
will define the timing of subsequent PUE calculations on a rolling annual basis.
6.1.3 Meter and measurement requirements
Measurement of E and E shall be undertaken using either
DC IT
— watt meters with the capability to report energy usage, or
— kilowatt-hour (kWh) meters that report the actual energy usage (true r.m.s), through the
simultaneous measurement of the voltage, current, and power factor over time.
NOTE Kilovolt-ampere (kVA), the product of voltage and current, is not an acceptable measurement. Though
the product of volts and amperes mathematically results in watts, the actual energy consumption is determined
by integrating a power factor-corrected value of volts and amperes. The frequency, phase variance, and load
reaction causes energy calculation difference between apparent energy and actual energy consumption. The
error is inherently significant when power delivery includes alternating current (AC). Kilovolt-ampere (kVA)
measurements may be used for other functions in the data centre; however, kVA is insufficient for efficiency
measurements.
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ISO/IEC 30134-2:2016(E)
6.2 Categories of power usage effectiveness
6.2.1 General
Three categories of PUE are defined as:
— Category 1 (PUE ) — provides a basic level of resolution of energy performance data;
1
— Category 2 (PUE ) — provides an intermediate level of resolution of energy performance data;
2
— Category 3 (PUE ) — provides an advanced level of resolution of energy performance data.
3
The higher categories provide progressively
— more accurate measurements of energy usage (as the measurements are made closer to the devices
that consume the energy), and
— greater scope for energy efficiency improvements.
Table 1 provides a summary of the locations for the measurement of IT equipment energy consumption
associated with each category. In all cases, the total data centre energy consumption is measured from
the utility service entrance that feeds all of the electrical and mechanical equipment used to power cool
and condition the data centre.
To properly assess PUE, it is critical to account for all systems that support the data centre, in addition
to the environmental conditions, reliability, security and availability requirements independent of
which PUE measurement category is chosen (see ISO/IEC 30134-1:2016, Annex A).
Table 1 — PUE categories
PUE PUE PUE
1 2 3
Location of IT equipment energy con- IT equipment
a b
UPS output PDU output
c
sumption measurement input
a
Includes impact of fluctuating IT and cooling loads.
b
Excludes impact of losses associated with PDU transformers and static switches.
c
Excludes impact of losses associated with electrical distribution components and non-IT related devices.
6.2.2 Category 1 (PUE ) — Basic resolution
1
The IT load is measured at the output of the UPS (or equivalent) equipment and may be read
— from the UPS front panel,
— through a meter on the UPS output, and
— in cases of multiple UPS modules through a single meter on the common UPS output bus.
The incoming energy is measured from the utility service entrance that feeds all of the electrical and
mechanical equipment used to power, cool, and condition the data centre.
If UPS or an equivalent power failure ride through or conditioning unit is not available, other categories
may apply.
6.2.3 Category 2 (PUE ) — Intermediate resolution
2
The IT load is measured at the output of the PDUs within the data centre and is typically read from the
PDU front panel or through a meter on the PDU output (with or without transformer, the measurement
point is then after the transformer). Individual branch circuit measurement is also acceptable for
Category 2.
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ISO/IEC 30134-2:2016(E)
6.2.4 Category 3 (PUE ) — Advanced resolution
3
The IT load is measured at the IT equipment within the data centre. This can be achieved either by
metered rack (e.g. plug strips) that monitors aggregate set of IT systems or at the receptacle level or by
the IT device itself. Note that non-IT loads shall be excluded from these measurements.
6.2.5 Measurement placement
Each category enables progressively improved accuracy of measurement of IT equipment energy
consumption, as the measurements are taken closer to the IT devices that consume energy.
7 Reporting of power usage effectiveness
7.1 Requirements
7.1.1 Standard construct for communicating PUE data
In order for a reported PUE to be meaningful, the reporting organization shall provide the following
information:
— data centre (including the boundaries of the structure) under inspection;
— PUE value;
— category.
The PUE category shall be provided as a subscript to the name of the metric, e.g. PUE for a Category
2
2 value.
7.1.2 Example of reporting PUE values
Using the construct of 7.1.1, Table 2 provides examples of specific PUE designations and their
interpretation.
Table 2 — Examples of PUE reporting
Example PUE designations Interpretation
Data centre X, PUE (2012–12–31) = 2,25 In the year 2012, the PUE value of data centre X was 2,25. It was
1
a Category 1 PUE.
Data centre Y, PUE (2013–06–30) = 1,75 In the period 2012–07–01 to 2013–06–30, the PUE value of data
1
centre Y was 1,75. It was a Category 1 PUE.
Data centre Z, PUE (2013–12–31) = 1,50 In the year 2013, the PUE value of data centre Z was 1,50. It was a
2
Category 2 PUE.
7.1.3 Data for public reporting of PUE
7.1.3.1 Required information
The following data shall be provided, when publicly reporting PUE data:
— contact information;
Only the organization’s name or contact should be displayed in public inquiries.
— data centre location information (address, county or region);
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ISO/IEC 30134-2:2016(E)
Only state or local region information are required to be displayed in public inquiries.
— measurement results: PUE with appropriate nomenclature including category designation.
7.1.3.2 Supporting evidence (where required by authorities having jurisdiction)
Information on the data centre which shall be available upon request as a minimum includes
— organization’s name, contact information and regional environmental description,
— measurement results: PUE with appropriate nomenclature,
— E and E ,
DC IT
— start and measurement(s) dates the assessments were completed,
— the accuracy level (IEC 62052 series and IEC 62053 series provide a reference for measurement of
electrical energy),
— report on the size of computer room, telecom room and control room spaces, and
— external environmental conditions consisting of minimum, maximum and average temperature,
humidity and altitude.
7.2 Recommendations
7.2.1 Use of PUE category
The PUE category should be appropriate to the expected value of PUE.
— PUE > 1,50: Category 1 to Category 3
— 1,50 ≥ PUE > 1,20: Category 2 or Category 3
— PUE ≤ 1,20: Category 3
7.2.2 Trend tracking data
The following information may be useful in tracking the PUE trends within a data centre:
— data centre size (facility square metres);
— total data centre design load for the facility (e.g. 10,2 MW);
— name of the possible auditor and method used for auditing;
— data centre contact information;
— data centre environmental conditions;
— data centre’s mission;
— data centre archetype percentages (e.g. 20 % web hosting, 80 % email);
— data centre commissioned date;
— numbers of servers, routers, and storage devices;
— average and peak server CPU utilization;
— percentage of servers using virtualization;
— average age of IT equipment by type;
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ISO/IEC 30134-2:2016(E)
— average age of facility equipment by type (cooling and power distribution equipment);
— data centre availability objectives (see ISO/IEC 30134-1:2016, Annex A);
— cooling and air-handling details.
NOTE Other KPIs within the ISO/IEC 30134 series can assist in the recording of the above information.
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ISO/IEC 30134-2:2016(E)
Annex A
(normative)
Energy measurements
A.1 Measuring energy and calculating power usage effectiveness
In Figure A.1, total data centre energy consumption is measured at or near the data centre’s utility
meter(s) to accurately reflect the energy entering the data centre (see Annex B for other energy sources)
in order that the measurement represents the total energy consumed in the data centre.
Building load - demand fr
...
DRAFT INTERNATIONAL STANDARD
ISO/IEC DIS 30134-2.2
ISO/IEC JTC 1/SC 39 Secretariat: ANSI
Voting begins on: Voting terminates on:
2015-08-03 2015-10-03
Information Technology — Data Centres — Key
performance indicators —
Part 2:
Power usage effectiveness (PUE)
Titre manque
ICS: 35.020
THIS DOCUMENT IS A DRAFT CIRCULATED
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ISO/IEC DIS 30134-2.2:2015(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
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ISO/IEC DIS 30134-2.2:2015(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2015, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO/IEC 2015 – All rights reserved
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ISO/IEC DIS 30134-2.2:2015-07-14
34 Contents Page
35
36 Introduction . 4
37 1 Scope . 5
38 2 Normative references . 5
39 3 Terms, definitions, abbreviations and symbols . 5
40 4 Applicable area of the Data Centre . 6
41 5 Determination of Power Usage Effectiveness (PUE) . 7
42 6 Measurement of Power Usage Effectiveness . 8
43 6.1 Measuring energy consumption . 8
44 6.2 Categories of Power Usage Effectiveness . 8
45 7 Reporting of Power Usage Effectiveness . 9
46 7.1 Requirements . 9
47 7.2 Supporting data for publicly reported PUE data . 10
48 Annex A (normative) Energy Measurements . 12
49 A.1 Measuring energy and calculating Power Usage Effectiveness . 12
50 A.2 Measurement locations. 12
51 A.3 Assessment frequencies . 13
52 Annex B (normative) Calculation of using various energy supplies . 14
53 B.1 Usage of different energy sources . 14
54 B.2 Examples of PUE calculation with various energy supplies . 15
55 B.3 Examples of PUE calculation with cogeneration using electricity and natural gas . 16
56 Annex C (informative) Interpretation of PUE . 18
57 C.1 General . 18
58 C.2 Data centre infrastructure versus IT equipment . 18
59 C.3 Interpretation in terms of energy . 18
60 C.4 Type of primary applications of data centre . 19
61 C.5 Better-than-perfect PUE measurements . 19
62 C.6 Comparing PUE results between data centres . 19
63 Annex D (normative)PUE derivatives . 21
64 D.1 General . 21
65 D.2 Partial PUE (pPUE) . 21
66 D.3 Design PUE (dPUE) . 25
67 D.4 Interim PUE (iPUE) . 27
68 Bibliography . 28
69
70
3
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ISO/IEC DIS 30134-2.2:2015-07-14
71 Information Technology ‑ Data Centres ‑ Key Performance
72 Indicators - Part 2: Power Usage Effectivenss (PUE)
73 Introduction
74 The global economy is now reliant on information and communication technologies and the associated
75 generation, transmission, dissemination, computation and storage of digital data. All markets have
76 experienced exponential growth in that data, for social, educational and business sectors and, whilst the
77 internet backbone carries the traffic there are a wide variety of data centres at nodes and hubs within both
78 private enterprise and shared/collocation.
79
80 The historical data generation growth rate exceeds the capacity growth rate of the information and
81 communications technology hardware and with less than half (in 2014) of the world's population having
82 access to an internet connection, that growth in data can only accelerate. In addition, with many governments
83 having ‘digital agendas‘ to provide both citizens and businesses with ever faster broadband access, the very
84 increase in network speed and capacity will, by itself, generate ever more usage (Javons Paradox). Data
85 generation and the consequential increase in data manipulation and storage, is directly linked to increasing
86 power consumption.
87
88 With this background it is clear that data centre growth, and power consumption in particular, is an inevitable
89 consequence and that growth will demand increasing power consumption despite the most stringent energy
90 efficiency strategies. This makes the need for Key Performance Indicators (KPIs) that cover the effective use
91 of resources (including but not limited to energy) and the reduction of carbon emissions essential.
92 Within the ISO/IEC 30134 series, the term “resource usage effectiveness” is more generally used for KPIs in
93 preference to “resource usage efficiency”, which is restricted to situations where the input and output
94 parameters used to define the KPI have the same units.
95 In order to determine the overall resource effectiveness or efficiency of a data centre, a holistic suite of
96 metrics is required. This International Standard specifies Power Usage Effectiveness (PUE), which has
97 become a popular metric to determine the efficient utilisation and distribution of energy resources within a
98 data centre.
99
100 NOTE: It is recognised that the term “efficiency” should be employed for PUE but “effectiveness” provides continuity with
101 earlier market recognition of the term.
102
103 This International Standard is one of a series of standards for such KPIs and has been produced in
104 accordance with ISO/IEC 30134-1, which defines common requirements for a holistic suite of KPIs for data
105 centre resource usage effectiveness or efficiency.
106 At the time of publication of this International Standard the ISO/IEC 30134 series comprises the following
107 • ISO/IEC 30134-1,Information Technology - Data Centres - Key Performance Indicators - Part 1: Overview and
108 General Requirements,
109 • ISO/IEC 30134-2,Information Technology - Data Centres - Key Performance Indicators - Part 2: Power Usage
110 Effectiveness (PUE),
111 • ISO/IEC 30134-3,Information Technology - Data Centres - Key Performance Indicators - Part 3: Renewable
112 Energy Factor (REF),
113 • ISO/IEC 30134-4,Information Technology - Data Centres - Key Performance Indicators - Part 4: Equipment
114 Energy Efficiency for Servers (ITEE ),
SV
115 • ISO/IEC 30134-5,Information Technology - Data Centres - Key Performance Indicators - Part 5: IT Equipment
116 Utilization for Servers (ITEU ).
SV
117 Additional standards in the series ISO/IEC 30134 will be developed, each describing a specific KPI for
118 resource usage effectiveness or efficiency.
119 These International Standards do not specify limits or targets for any KPI and do not describe or imply, unless
120 specifically stated, any form of aggregation of individual KPIs into a combined nor an overall KPI for data
121 centre resource usage effectiveness or efficiency.
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122 1 Scope
123 This International Standard specifies the Power Usage Effectiveness (PUE) as a Key Performance Indicator
124 (KPI) to quantify the efficient use of energy in the form of electricity.
125 NOTE: It is recognised that the term “efficiency” should be employed for PUE but “effectiveness” provides continuity with
126 earlier market recognition of the term.
127 This international Standard
128 a) defines the Power Usage Effectiveness (PUE) of a data centre,
129 b) introduces PUE measurement categories,
130 c) describes the relationship of this KPI to a data centre’s infrastructure, information technology equipment
131 and information technology operations,
132 d) defines the measurement, the calculation and the reporting of the parameter,
133 e) provides information on the correct interpretation of the PUE.
134 PUE derivatives are described in Annex D.
135 2 Normative references
136 The following documents, in whole or in part, are normatively referenced in this document and are
137 indispensable for its application. For dated references, only the edition cited applies. For undated references,
138 the latest edition of the referenced document (including any amendments) applies.
139 ISO/IEC 30134-1, Information Technology - Data Centres - Key Performance Indicators - Part 1: Overview
140 and General Requirements
141 3 Terms, definitions, abbreviations and symbols
142 3.1 Terms and definitions
143 For the purposes of this document the definitions of ISO/IEC 30134-1 and the following apply.
144 3.1.1
145 information technology (IT) equipment energy consumption
146 energy consumed, measured in kilowatt hours (kWh), by equipment that is used to store, process, and
147 transport data within the computer room, telecommunication room and control room spaces
148 Note 1 to entry: Examples are servers, storage equipment, and telecommunications equipment.
149 3.1.2
150 power distribution unit (PDU)
151 equipment that allocates or partitions power or other energy consuming equipment
152 3.1.3
153 Power Usage Effectiveness (PUE)
154 ratio of the data centre total energy consumption to information technology equipment energy consumption,
155 calculated, measured or assessed across the same period.
156 Note 1 to entry: Sometimes the inverse value of PUE, referred to as Data Centre Infrastructure Efficiency
157 (DCiE), is used.
158 3.1.4
159 partial Power Usage Effectiveness (pPUE)
160 derivative of PUE, which is the ratio of the total energy consumption within a defined boundary to the
161 information technology equipment energy consumption
162
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163
164 3.1.5
165 designed Power Usage Effectiveness (dPUE)
166 derivative of PUE, which is the a projected PUE determined by the design targets of the data centre
167 3.1.6
168 Interim Power Usage Effectiveness (iPUE)
169 derivative of PUE, which is measured over a specified time other than a year
170 3.1.7
171 total data centre energy consumption
172 total energy consumption for all energy types serving the data centre, measured in kWh at its boundary
173 Note 1 to entry: Energy measured with energy metering devices at the boundary of the data centre.
174 Note 2 to entry: This includes electricity, natural gas and district utilities such as supplied chilled water or condenser
175 water.
176 3.2 Abbreviations
177 For the purposes of this document the abbreviations of ISO/IEC 30134-1 and the following apply:
178 CRAC Computer Room Air Conditioner units
179 CRAH Computer Room Air Handler units
180 dPUE designed Power Usage Effectiveness
181 DX Direct Expansion
182 iPUE interimPower Usage Effectiveness
183 IT information technology
184 PDU Power Distribution Unit
185 pPUE partial Power Usage Effectiveness
186 PUE Power Usage Effectiveness
187 r.m.s root mean square
188 ROI return on investment
189 UPS Uninterruptible Power Supply
190 3.3 Symbols
191 For the purposes of this document the following symbols apply:
192 E total data centre energy consumption (annual)
DC
193 E IT equipment energy consumption (annual)
IT
194 4 Applicable area of the data centre
195 Power Usage Effectiveness (PUE) as specified in this standard
196 a) is associated with the data centre infrastructure within its boundaries only,
197 b) describes the infrastructures energy efficiency relative to facilities with given environmental conditions, IT
198 load characteristics, availability requirements, maintenance, and security requirement,
199 c) illustrates the energy allocation of a data centre,
200 d) measures the relationship between the total data centre energy consumed and the IT equipment energy
201 consumed.
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202 When viewed in the proper context, PUE provides effective guidance and useful insight into the design of
203 efficient power and cooling architectures, the deployment of equipment within those architectures, and the
204 operation of that equipment.
205 PUE provides a means to determine
206 1) opportunities for the improvement of the operational efficiency of a data centre,
207 2) the improvement of the designs and processes of a data centre over time,
208 3) a design target or goal for new data centres, which includes the anticipated IT load range.
209 PUE does not take into account the
210 - energy efficiency of the IT load, its utilization, or productivity,
211 - impact of on-site electricity generation,
212 - efficiency of other resources such as human resource, space or water,
213 - use of renewable energy resources or accounts for re-use of waste by-products, such as heat.
214 PUE is not a
215 data centre productivity metric,
216 a standalone, comprehensive resource efficiency metric.
217 Derivatives of PUE which are useful in certain circumstances as described in Annex D.PUE should not be
218 used to compare different data centres.
219 5 Determination of Power Usage Effectiveness (PUE)
220 PUE is defined as:
E
DC
221 PUE (1)
E
IT
222 where
223 E = total data centre energy consumption (annual)
DC
224 E = IT equipment energy consumption (annual)
IT
225 By definition, the calculated PUE is always greater than 1.
226 Where the only energy source is from the electrical utility, then E is determined by the energy measured at
DC
227 the utility meter. PUE may be applied in mixed use buildings that allow of the differentiation between the
228 energy used for the data centre and that for other functions. Alternatively, the derivative partial PUE (pPUE)
229 may be applied (see Annex D).
230 E includes but is not limited to
IT
231 a) IT equipment (e.g. storage, processing and transport equipment),
232 b) supplemental equipment (e.g. keyboard/video/mouse (KVM) switches, monitors, and work-
233 stations/laptops used to monitor, manage, and/or control the data centre).
234 E includes E plus all the energy that is consumed to support the following infrastructures
DC IT
235 1) power delivery - including UPS systems, switchgear, generators, power distribution units (PDUs),
236 batteries, and distribution losses external to the IT equipment,
237 2) cooling system - including chillers, cooling towers, pumps, computer room air handling units (CRAHs),
238 computer room air conditioning units (CRACs), and direct expansion air handler (DX) units;
239 3) others including data centre lighting, elevator, security system, and fire suppression system.
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240 6 Measurement of Power Usage Effectiveness
241 6.1 Measuring energy consumption
242 6.1.1 General
243 In order to calculate PUE, it is necessary to measure E and E . This is not a trivial task, especially within
DC IT
244 existing data centres which may require the installation of instrumentation to collect the data.
245 NOTE: Although measurement of E and E are adequate to calculate PUE for the defined equipment and supporting
DC IT
246 infrastructure, more monitoring data of logical subsets is necessary to assess areas for potential improvements and to
247 evaluate the resulting improvements to PUE across the data centre.
248 6.1.2 Measurement period and frequency
249 The calculation of PUE requires the recording and documenting of E and E over a coincident period of
DC IT
250 twelve months. This standard does not specify the frequency of measurements of E and E , since PUE is
DC IT
251 calculated on an annual timeframe. However, the frequency of measurement employed will define the timing
252 of subsequent PUE calculations on a rolling annual basis.
253 6.1.3 Meter and measurement requirements
254 Measurement of E and E shall be undertaken using either
DC IT
255 a) watt meters with the capability to report energy usage
256 or
257 b) kilowatt-hour (kWh) meters that report the actual energy usage (true r.m.s), via the simultaneous
258 measurement of the voltage, current, and power factor over time.
259 NOTE: Kilovolt-ampere (kVA), the product of voltage and current, is not an acceptable measurement. Though the product
260 of volts and amperes mathematically results in watts, the actual energy consumption is determined by integrating a power
261 factor corrected value of volts and amperes. The frequency, phase variance, and load reaction causes energy calculation
262 difference between apparent energy and actual energy consumption. The error is inherently significant when power
263 delivery includes alternating current (AC). Kilovolt-ampere (kVA) measurements may be used for other functions in the
264 data centre, however, kVA is insufficient for efficiency measurements.
265 6.2 Categories of Power Usage Effectiveness
266 6.2.1 General
267 Three categories of PUE are defined:
268 a) Category 1 (PUE ), which provides a basic level of resolution of energy performance data;
1
269 b) Category 2 (PUE ), which provides an intermediate level of resolution of energy performance data;
2
270 c) Category 3 (PUE ), which provides an advanced level of resolution of energy performance data.
3
271 The higher categories provide progressively
272 1) more accurate measurements of energy usage (as the measurements are made closer to the devices
273 that consume the energy),
274 2) greater scope for energy efficiency improvements.
275 Table 1 provides a summary of the locations for the measurement of IT equipment energy consumption
276 associated with each category. In all cases, the total data centre energy consumption is measured from the
277 utility service entrance that feeds all of the electrical and mechanical equipment used to power cool and
278 condition the data centre.
279 To properly assess PUE, it is critical to account for all systems that support the data centre, in addition to the
280 environmental conditions, reliability, security and availability requirements independent of which PUE
281 measurement Category is chosen (see ISO/IEC 30134-1:201X, Annex B).
282
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283
284 Table 1 - PUE categories
PUE PUE PUE
1 2 3
a b c
Location of IT equipment energy UPS output PDU output IT equipment input
consumption measurement
a
includes impact of fluctuating IT and cooling loads.
b
excludes impact of losses associated with PDU transformers and static switches.
c
excludes impact of losses associated with electrical distribution components and non-IT related devices.
285
286 6.2.2 Category 1 (PUE ) – basic resolution
1
287 The IT load is measured at the output of the UPS (or equivalent) equipment and may be read
288 a) from the UPS front panel,
289 b) through a meter on the UPS output,
290 c) in cases of multiple UPS modules through a single meter on the common UPS output bus.
291 The incoming energy is measured from the utility service entrance that feeds all of the electrical and
292 mechanical equipment used to power, cool, and condition the data centre.
293 If UPS or an equivalent power failure ride through or conditioning unit is not available, other categories may
294 apply.
295 6.2.3 Category 2 (PUE ) – intermediate resolution
2
296 The IT load is measured at the output of the PDUs within the data centre and is typically read from the PDU
297 front panel or through a meter on the secondary of the PDU transformer. Individual branch circuit
298 measurement is also acceptable for Category 2.
299 6.2.4 Category 3 (PUE ) – advanced resolution
3
300 The IT load is measured at the IT equipment within the data centre. This can be achieved either by metered
301 rack (e.g. plug strips) that monitors aggregate set of IT systems or at the receptacle level or by the IT device
302 itself. Note that non-IT loads shall be excluded from these measurements.
303 6.2.5 Measurement placement
304 Each Category enables progressively improved accuracy of measurement of energy usage, as the
305 measurements are taken closer to the IT devises that consume energy.
306 7 Reporting of Power Usage Effectiveness
307 7.1 Requirements
308 7.1.1 Standard construct for communicating PUE data
309 In order for a reported PUE to be meaningful, the reporting organization shall provide the following
310 information
311 a) the data centre (including the boundaries of the structure) under inspection,
312 b) the PUE value,
313 c) the category,
314 d) the termination date of the period of measurement.
315 The PUE category shall be provided as a subscript to the name of the metric, e.g. PUE for a category 2
2
316 value.
317 The PUE category should be appropriate to the expected value of PUE:
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318 1) PUE > 1,5: Category 1 to Category 3;
319 2) 1,5 > PUE > 1,2: Category 2 or Category 3;
320 3) 1,2 > PUE: Category 3.
321 7.1.2 Example of reporting PUE values
322 Given the construct above, Table 2 provides examples of specific PUE designations and their interpretation.
323 Table 2 – Examples of PUE reporting
Sample PUE Designations Interpretation
In the year 2012 the PUE value of data centre X was
Data centre X, PUE (2012-12-31) = 2,25
1
2,25. It was a category 1 PUE.
In the period 2012-07-01to 2013-06-30 the PUE value
Data centre Y, PUE (2013-06-30) = 1,75
1
of data centre Y was 1,75. It was a category 1 PUE.
In the year 2013 the PUE value of data centre Z was
Data centre Z, PUE (2013-12-31) = 1,5
2
1,5. It was a category 2 PUE.
324
325 7.2 Supporting data for publicly reported PUE data
326 7.2.1 Required information
327 The following data shall be provided, when publicly reporting PUE data
328 a) contact information;
329 NOTE: Only the organization’s name or contact should be displayed in public inquiries.
330 b) data centre location information (address, county or region),
331 NOTE: Only state or local region information should be displayed in public inquiries.
332 c) measurement results: PUE with appropriate nomenclature including category designation,
333 d) measurement completion date: completion date identifies the annual period of the assessment.
334 7.2.2 Required supporting evidence
335 Information on the data centre which shall be available upon request includes
336
337 a) organization’s name, contact information and regional environmental description,
338 b) measurement results: PUE with appropriate nomenclature,
339 c) E and E ,
DC IT
340 d) start and measurement(s) dates the assessments were completed,
341 e) the accuracy level (IEC 62052 series and IEC 62053 series provide a reference for measurement of
342 electrical energy),
343 f) report on the size of computer room, telecom room and control room spaces,
344 g) external environmental conditions consisting of minimum, maximum and average temperature, humidity
345 and altitude.
346 7.2.3 Optional data
347 The following information may be useful in tracking the PUE trends within a data centre
348 a) data centre size (facility square meters),
349 b) total data centre design load for the facility (e.g. 10,2 MW),
350 c) name of the possible auditor and method used for auditing,
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351 d) data centre contact information,
352 e) data centre environmental conditions,
353 f) data centre’s mission,
354 g) data centre archetype percentages (e.g. 20% web hosting, 80% email),
355 h) data centre commissioned date,
356 i) numbers of servers, routers, and storage devices,
357 j) average and peak server CPU utilization,
358 k) percentage of servers using virtualization,
359 l) average age of IT equipment by type,
360 m) average age of facility equipment by type (cooling and power distribution equipment),
361 n) data centre category of reliability (see ISO/IEC 30134-1:201X, Annex B),
362 o) cooling and air-handling details.
363 NOTE: Other KPI’s within the ISO/IEC 30134 series can assist in the recording of the above information.
364
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ISO/IEC DIS 30134-2.2:2015-07-14
365 Annex A
366 (normative)
367
368 Energy measurements
369 A.1 Measuring energy and calculating Power Usage Effectiveness
370 In Figure A.1, total data centre energy consumption is measured at or near the data centre’s utility meter(s) to
371 accurately reflect the energy entering the data centre (see Annex B for other energy sources) in order that the
372 measurement represents the total energy consumed in the data centre.
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373
374 Figure A.1 - Schematicof PUE calculation from measurements
375 Only the data centre portion of a facility’s utility consumption meter relevant to the data centre shall be
376 measured, since including in the calculation any energy that is not intended to be consumed in the data
377 centre would result in a non-compliant PUE calculation. For example, if a data centre resides in an office
378 building, the total energy drawn from the utility will be the sum of the total facility energy consumption for the
379 data centre and the total energy consumed by the non-data centre offices in the building. In this case, the
380 data centre administra
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