IEC 60721-2-1:2013

IEC 60721-2-1 ®
Edition 2.0 2013-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Classification of environmental conditions –
Part 2-1: Environmental conditions appearing in nature – Temperature and
humidity
Classification des conditions d'environnement –
Partie 2-1: Conditions d'environnement présentes dans la nature – Température
et humidité
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IEC 60721-2-1 ®
Edition 2.0 2013-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Classification of environmental conditions –

Part 2-1: Environmental conditions appearing in nature – Temperature and

humidity
Classification des conditions d'environnement –

Partie 2-1: Conditions d'environnement présentes dans la nature – Température

et humidité
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX L
ICS 19.040 ISBN 978-2-83220-899-1

– 2 – 60721-2-1 © IEC:2013
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions, abbreviations, quantities and units . 6
4 General information regarding data collection and analysis . 6
5 General validation process . 7
6 Open air climates . 8
6.1 General . 8
6.2 Environmental parameters . 8
6.3 Identification of statistical open-air climates . 8
6.4 Map of open-air climates . 9
Annex A (informative) Map of climate classification . 10
Bibliography . 11

Figure A.1 – Climate classifications . 10

Table 1 – Climate classifications . 7
Table 2 – Climate classification definitions . 7
Table 3 – Classification of climates by extreme daily mean values . 8
Table 4 – Classification of climates by annual extreme values . 8
Table 5 – Classification of climates by absolute extreme value . 9

60721-2-1 © IEC:2013 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
CLASSIFICATION OF ENVIRONMENTAL CONDITIONS –

Part 2-1: Environmental conditions appearing in nature –
Temperature and humidity
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60721-2-1 has been prepared by IEC technical committee 104:
Environmental conditions, classification and methods of test.
This second edition cancels and replaces the first edition published in 1982 and its
amendment 1 (1987), and constitutes a technical revision.
The main changes with respect to the previous edition are in the definitions of climate types.

– 4 – 60721-2-1 © IEC:2013
The text of this standard is based on the following documents:
FDIS Report on voting
104/610/FDIS 104/617/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all the parts in the IEC 60068 series, under the general title Classification of
environmental conditions, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
60721-2-1 © IEC:2013 – 5 –
INTRODUCTION
Electrotechnical products are used in almost all areas of the world under varying climatic
conditions and have to meet the stresses imposed by these climatic conditions with the
necessary reliability. A detailed knowledge of the climatic conditions to which the product will
be subjected is necessary in the design stage to ensure that reliability is met.
Data on open-air temperature and humidity have been collected and statistically processed for
many years throughout the world. Such data is represented in this part of IEC 60721.
In addition to open-air temperature, temperature stresses on a product depend on a number
of other environmental parameters, for example solar radiation, air velocity or heating from
adjacent equipment.
The effects of humidity depend on temperature, temperature changes and impurities in the
humid air.
In many cases the extremes of temperature and humidity are of great importance even if they
occur for a short time. In other cases, where large time constants for heat or water
penetration are involved, the mean values of temperature and humidity over a certain period
may be more important.
It has therefore been considered useful to present here both the mean value over many years
of the annual extreme values of temperature and humidity, which will occur only for short
periods (a few hours), and the mean value over many years of the extreme daily mean values
of temperature
...