EN ISO 15927-6:2007

SLOVENSKI STANDARD
01-januar-2008
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Hygrothermal performance of buildings — Calculation and presentation of climatic data
— Part 6: Accumulated temperature differences (degree days) (ISO 15927-6:2007)
Wärme und feuchteschutztechnisches Verhalten von Gebäuden — Berechnung und
Darstellung von Klimadaten — Teil 6: Akkumulierte Temperaturdifferenzen (Gradtage)
(ISO 15927 6:2007)
Performance hygrothermique des bâtiments — Calcul et présentation des données
climatiques — Partie 6: Différences accumulées de la température (en degrés par jour)
(ISO 15927 6:2007)
Ta slovenski standard je istoveten z: EN ISO 15927-6:2007
ICS:
07.060 Geologija. Meteorologija. Geology. Meteorology.
Hidrologija Hydrology
91.120.10 Toplotna izolacija stavb Thermal insulation
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 15927-6
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2007
ICS 07.060; 91.120.10
English Version
Hygrothermal performance of buildings - Calculation and
presentation of climatic data - Part 6: Accumulated temperature
differences (degree-days) (ISO 15927-6:2007)
Performance hygrothermique des bâtiments - Calcul et Wärme- und feuchteschutztechnisches Verhalten von
présentation des données climatiques - Partie 6: Écarts de Gebäuden - Berechnung und Darstellung von Klimadaten -
température cumulés (degrés-jour) (ISO 15927-6:2007) Teil 6: Akkumulierte Temperaturdifferenzen (Gradtage)
(ISO 15927-6:2007)
This European Standard was approved by CEN on 30 June 2007.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
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EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 15927-6:2007: E
worldwide for CEN national Members.

Contents Page
Foreword.3

Foreword
This document (EN ISO 15927-6:2007) has been prepared by Technical Committee ISO/TC 163 "Thermal
performance and energy use in the built environment" in collaboration with Technical Committee CEN/TC 89
"Thermal performance of buildings and building components", the secretariat of which is held by SIS.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by March 2008, and conflicting national standards shall be withdrawn at
the latest by March 2008.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 15927-6:2007 has been approved by CEN as a EN ISO 15927-6:2007 without any
modification.
INTERNATIONAL ISO
STANDARD 15927-6
First edition
2007-09-01
Hygrothermal performance of
buildings — Calculation and presentation
of climatic data —
Part 6:
Accumulated temperature differences
(degree days)
Performance hygrothermique des bâtiments — Calcul et présentation
des données climatiques —
Partie 6: Différences accumulées de la température (en degrés par jour)

Reference number
ISO 15927-6:2007(E)
©
ISO 2007
ISO 15927-6:2007(E)
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ii © ISO 2007 – All rights reserved

ISO 15927-6:2007(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and units . 1
4 Direct calculation of accumulated temperature differences . 3
5 Estimation of totals. 6
6 Reference altitude. 7
7 Accuracy and presentation of data. 8
Annex A (informative) Estimation of monthly accumulated temperature differences from
climatological statistics . 10
Bibliography . 13

ISO 15927-6:2007(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 15927-6 was prepared by the European Committee for Standardization (CEN) Technical Committee
CEN/TC 89, Thermal performance of buildings and building components, in collaboration with Technical
Committee ISO/TC 163, Thermal performance and energy use in the built environment, Subcommittee SC 2,
Calculation methods, in accordance with the Agreement on technical cooperation between ISO and CEN
(Vienna Agreement).
ISO 15927 consists of the following parts, under the general title Hygrothermal performance of buildings —
Calculation and presentation of climatic data:
⎯ Part 1: Monthly means of single meteorological elements
⎯ Part 2: Hourly data for design cooling load
⎯ Part 3: Calculation of a driving rain index for vertical surfaces from hourly wind and rain data
⎯ Part 4: Hourly data for assessing the annual energy use for heating and cooling
⎯ Part 5: Data for design heat load for space heating
⎯ Part 6: Accumulated temperature differences (degree days)

iv © ISO 2007 – All rights reserved

ISO 15927-6:2007(E)
Introduction
Accumulated temperature differences are a relatively simple form of climatic data, useful as an index of
climate severity as it affects energy use for space heating.
Calculation or estimation of accumulated temperature differences in this part of ISO 15927 is based on the
concept of a base temperature. The base temperature reflects the point at which buildings begin to need
heating to maintain the required internal temperatures. This is the external temperature below which the
heating plant is assumed to come into operation. For some purposes, such as development of energy policy,
the need is for a single base temperature that can be taken to represent an average value for the whole built
stock and overall climate. For other purposes, it is better to determine a base temperature appropriate to an
individual building and time of year.
This part of ISO 15927 meets these needs by including both exact and approximate methods of determining
accumulated temperature differences to both standard and variable base temperatures. Some methods
include the possibility of a threshold temperature (e.g. a daily mean air temperature lower than the base
temperature, above which accumulated temperature differences are not counted). This approach is found in
certain national methods of computation. It is, however, not covered in this part of ISO 15927 because it is
considered to be less flexible than the methods given, in which accumulated temperature differences are
assessed for a base temperature appropriate to the thermal performance of the building (taking account of
other climatic conditions such as solar irradiation).
Accumulated temperature differences computed and presented in accordance with this part of ISO 15927 are
suitable for various purposes including the following:
a) providing an index of climatic severity as it affects energy use for space heating (the comparison use);
b) monitoring the amount of energy used by a heating plant, and thus its efficiency (the energy management
use);
c) comparing the actual energy consumption for heating in a specific period with the consumption in a
standardized period in order to determine the measured rating (the energy modelling use);
d) predicting the economic consequences of different levels of energy efficiency (e.g. through thermal
insulation) for the building stock as a whole or for different classes of building (the energy policy use).
Energy management [list item b)] requires new accumulated temperature difference data at regular intervals,
such as meteorological station data or data representative of a climatic region, calculated to standard base
temperatures, published for each month of the heating season as soon as these can be computed from
verified meteorological observations.
Comparison, energy modelling and energy policy [list items a), c) and d)] require meteorological station data,
data representative of a climatic region or mapped data, collected over many years (possibly giving extremes
as well as mean values), to typify the severity of the climate of a locality, area or region. For list item b),
accumulated temperature differences are best suited to modelling the energy performance of relatively small
buildings with simple heating systems and controls, using “steady-state” thermal analysis. Modelling the
performance of larger or more complex buildings can require more extensive climatological data sets, such as
full or short “test reference years” which are outside the scope of this part of ISO 15927.
In principle the equations in this part of ISO 15927 can be reversed to deal with accumulated temperature
differences for assessing energy use in cooling or air-conditioning buildings (“cooling degree-hours” or
“cooling degree-days”). However, as the air conditioning demand depends as much on solar gain and external
humidity as temperature, the results are not a reliab
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