ISO 14438:2002

INTERNATIONAL ISO
STANDARD 14438
First edition
2002-06-15

Glass in building — Determination of
energy balance value — Calculation
method
Verre dans la construction — Détermination de la valeur du bilan
énergétique — Méthode de calcul




Reference number
ISO 14438:2002(E)
©
ISO 2002

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ISO 14438:2002(E)
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ii © ISO 2002 – All rights reserved

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ISO 14438:2002(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 3.
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 International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 14438 was prepared by the European Committee for Standardization (CEN) in collaboration with Technical
Committee ISO/TC 160, Glass in building, Subcommittee SC 2, Use considerations, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
Throughout the text of this document, read ".this European Standard." to mean ".this International Standard.".
Annexes A and B of this International Standard are for information only.


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ISO 14438:2002(E)
Contents
page
Foreword.v
1 Scope.1
2 Normative references .1
3 Symbols .1
4 Basic formula.2
5 Basic material properties.2
6 Solar radiation incident, H .3
p
7 Degree day data, D .3
p
8 Period of application, p .3
9 Principal values and presentation.3
10 Alternative simplification of principal values and presentation.4
Annex A (informative) Examples of climatic data p, D and H .5
p p
Annex B (informative) Examples of calculation of the energy balance value .6
Bibliography .8
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ISO 14438:2002(E)
Foreword
This document (EN ISO 14438:2002) has been prepared by Technical Committee CEN/TC 129 "Glass in building",
the secretariat of which is held by IBN, in collaboration with Technical Committee ISO/TC 160 "Glass in building".
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 December 2002, and conflicting national standards shall be withdrawn at the latest
by December 2002.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard : Austria, Belgium, Czech Republic, Denmark, Finland,
France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain,
Sweden, Switzerland and the United Kingdom.
A first Formal Vote took place within CEN as prEN 14026 between 2000-10-19 and 2000-12-19.
Annexes A and B are informative.
This standard includes a Bibliography.
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ISO 14438:2002(E)
1 Scope

This European Standard specifies a calculation method to determine the energy balance value of glazing. This
European Standard applies to transparent materials such as glass and combinations of glass used to glaze
windows in buildings.
This method is intended to evaluate the balance of heat loss and useful heat gain by solar radiation entering the
building through the glazing for a given period by means of an average rate of loss (or gain) of heat called the
energy balance value.
The method enables producers to compare the performance of their glazing products. The energy balance value
should not be used for energy use or heating capacity calculations in buildings.
2 Normative references
This European Standard incorporates by dated or undated references, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed hereafter. For
dated references, subsequent amendments to or revisions of any of these publications apply to this European
Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the
publication referred to applies (including amendments).
EN 410 Glass in building - Determination of luminous and solar characteristics of glazing
EN 673 Glass in building - Determination of thermal transmittance (U value) - Calculation method
EN 674 Glass in building - Determination of thermal transmittance (U value) - Guarded hot plate method
EN 675 Glass in building - Determination of thermal transmittance (U value) - Heat flow meter method
EN 832 Thermal performance of buildings - Calculation of energy use for heating - Residential buildings
3 Symbols
D degree days K·24 h
utility factor


H unobstructed incident solar radiation 2
kWh/m
g total solar energy transmittance (solar factor)
U U
thermal transmittance ( value) 2
W/(m ·K)
f factor due to glazing maintenance and shadow effects
S function of H and D characterising a given region 2
W/(m ·K)
E energy balance value 2
W/(m ·K)
Subscripts
p period of application
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ISO 14438:2002(E)
4 Basic formula

The energy balance value, E, for a given period is calculated according to the following equation:


g
f
H
p
E U
  (1)
D
p
where:
U is the U value of the glazing;

is the utility factor;
f is the factor due to glazing maintenance and shadow effects
;
g is the glazing total solar energy transmittance (solar factor);
H is the unobstructed incident solar radiation during the given period;
p
D is the degree
...