ISO 9459-1:1993

INTERNATIONAL
IS0
STANDARD 9459-1
First edition
1993-I l-01
Solar heating - Domestic water heating
systems -
Part 1:
Performance rating procedure using indoor
test methods
Chauffage solaire - Systkmes de chauffage de I’eau sanitaire -
Partie 7: Mkthodes d’essai 4 I’intbrieur pour Evaluation des performances
Reference number
IS0 9459-l :1993(E)
IS0 9459=1:1993(E)
Contents
Page
1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*. I
2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .* 1
3 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
4 Symbols and units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5 System classifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.1 Attribute 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*. 6
5.2 Attribute 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . .*. 6
5.3 Attribute 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.4 Attribute 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*. 6
5.5 Attribute 5 . . . . . . . . . . . . .*. 6
5.6 Attribute 6 . . . . . . . . . . . . . . . . . . . . . . .*.*. 6
5.7 Attribute 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6 Requirements for indoor testing of solar domestic hot water
systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.1 System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.2 Measurement requirements . 8
6.3 Test method requirements . 9
7 Indoor test procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I2
7.1 Solar-only and solar-preheat systems 12
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.2 Solar-plus-supplementary systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I3
7.3 Hot water - Continuous draw test - Solar energy only . . . 14
8 Recording and reporting of data I4
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Annexes
A Test day specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
0 IS0 1993
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l W-1 211 Geneve 20 l Switzerland
Printed in Switzerland
ii
0 IS0 IS0 9459-l :1993(E)
B Collector loop heater - Equations to be used in controlling thermal
output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C Calculation of spectrum-weighted values of optical properties
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
D Calculation of equivalent irradiance
E Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .~.

0 IS0
IS0 9459=1:1993(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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. IS0
collaborates closely with the International Electrotechnical Commission
(I EC) on all matters of electrotechnical standardization.
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.
International Standard IS0 9459-l was prepared by Technical Committee
lSO/TC 180, Solar energy, Subcommittee SC 4, Systems - Thermal
performance, reliability and durability.
IS0 9459 consists of the following parts, under the general title Solar
- Domestic water heating systems:
heating
- Part I: Performance rating using indoor test methods
- Part 2: Performance test for solar only systems
- Part 3: Performance test for solar plus supplementary systems
- Part 4: System performance characterkation by means of compo-
nent tests and computer simulation
- Part 5: System performance characterization by means of whole
system tests and computer simulation
Annexes A, B, C and D form an integral part of this part of IS0 9459. An-
nex E is for information only.

0 IS0
IS0 9459=1:1993(E)
Introduction
International Standard IS0 9459 has been developed to help facilitate the
international comparison of solar domestic water heating systems. Be-
cause a generalized performance model which is applicable to all systems
has not yet been developed, it has not been possible to obtain an inter-
national consensus for one test method and one standard set of test
conditions. It has therefore been decided to promulgate the currently
available simple methods while work continues to finalize the more
broadly applicable procedures. The advantage of this approach is that each
part can proceed on its own.
IS0 9459 is divided into five parts within three broad categories, as de-
scribed below.
Rating test
IS0 9459-1, Performance rating using indoor test methods, involves test-
ing for periods of one day for a standardized set of reference conditions.
The results, therefore, allow systems to be compared under identical so-
lar, ambient and load conditions.
Black box correlation procedures
IS0 9459-2 is applicable to solar-only systems and solar-preheat systems.
The performance test for solar-only systems is a “black box” procedure
which produces a family of “input-output” characteristics for a system.
The test results may be used directly with daily mean values of local solar
irradiation, ambient air temperature and cold water temperature data to
predict annual system performance.
IS0 9459-3 applies to solar plus supplementary systems. The performance
test is a “black box” procedure which produces coefficients in a corre-
lation equation that can be used with daily mean values of local solar
irradiation, ambient air temperature and cold water temperature data to
predict annual system performance. The test is limited to predicting annual
performance for one load pattern.
Testing and computer simulation
IS0 9459-4, a procedure for characterizing annual system performance,
uses measured component characteristics in the computer simulation
program “TRNSYS”. Procedures for characterizing the performance of
system components other than collectors are also presented in this part
of IS0 9459. Procedures for characterizing the performance of collectors
are given in IS0 9806-1, IS0 9806-2 and IS0 9806-3.
IS0 9459-5 presents a procedure for dynamic testing of complete systems
to determine system parameters for use in a computer model. This model
may be used with hourly values of local solar irradiation, ambient air tem-
perature and cold water temperature data to predict annual system per-
formance.
0 IS0
IS0 9459=1:1993(E)
The procedures defined in IS0 9459-2, IS0 9459-3, IS0 9459-4 and IS0
9459-5 for predicting yearly performance allow the output of a system to
be determined for a range of climatic conditions.
The results of tests performed in accordance with IS0 9459-l provide a
ratin g for a sta ndard .
day
The results of tests performed in accordance with IS0 9459-2 permit
performance predictions for a range of system loads and operating con-
ditions, but only for an evening draw-off.
The results of tests performed in accordance with IS0 9459-4 or IS0
9459-5 are directly comparable. These procedures permit performance
predictions for a range of system loads and operating conditions.
System reliability and safety will be dealt with in a future standard.

IS0 9459=1:1993(E)
INTERNATIONAL STANDARD 0 IS0
Solar heating - Domestic water heating systems -
Part I:
Performance rating procedure using indoor test methods
It is not intended to be used for testing the individual
1 Scope
components of the system, nor is it intended to
abridge any safety or health requirements.
This part of IS0 9459 establishes a uniform indoor
test method for rating solar domestic water heating
systems for thermal performance, under benchmark
2 Normative references
conditions.
The following standards contain provisions which,
It applies only to solar water heating systems de-
through reference in this text, constitute provisions
signed solely to heat potable water to be supplied for
of this part of IS0 9459. At the time of publication, the
domestic water usage.
editions indicated were valid. All standards are subject
to revision, and parties to agreements based on this
The test procedures described in this part of IS0 9459
part of IS0 9459 are encouraged to investigate the
are applicable to systems of solar storage capacity of
possibility of applying the most recent editions of the
0,6 m3 or less. It includes procedures for testing solar
standards indicated below. Members of IEC and IS0
domestic hot water systems either with solar
maintain registers of currently valid International
irradiance simulators or thermal simulation (non-
Standards.
irradiated) methods.
IS0 9059:1990, Solar energy - Calibration of field
The test procedures in this part of IS0 9459 which
by comparison to a reference
pyrheliome ters
employ a non-irradiated solar collector array in series
pyrheliome ter.
with a conventional heat source do not apply to inte-
gral collector storage systems, nor to systems in
IS0 9060: 1990, Solar energy - Specification and
which thermosiphon flow occurs, nor to any system
classifica tion 0 f instruments for measuring
employing a collector/heat transfer fluid combination hemispherical solar and direct solar radiation.
which cannot be tested in accordance with the col-
lector test. IS0 9806-I :- l) , Test methods for solar collectors -
Part 1: Thermal performance of glazed liquid heating
The test procedures in this part of IS0 9459 do not collectors including pressure drop.
require the solar water heating system to be sub-
IS0 9845-l : 1992, Solar energy - Reference solar
jected to freezing conditions. Consequently, the en-
spectral irradiance at the ground at different receiving
ergy consumed or lost by a system while operating in
- Part 1: Direct normal and hemispherical
the freeze-protection mode is not determined. conditions
solar irradiance for air mass 1,5.
This part of IS0 9459 is not generally applicable to
IS0 9846:-J, Solar energy - Calibration of a
concentrating or evacuated tube systems, unless the
pyranometer using a reference pyrheliometer.
collimation requirements of 6.3.1.3 are met.
1) To be published.
0 IS0
IS0 9459=1:1993(E)
World Meteorological Organization, Guide to the thermal energy so gained to a fluid passing
Meteorological lnstrumen ts and Methods of Obser- through it.
vation, No. 8, 5th edition, WMO, Geneva, 1983,
Chapter 9 - World radiometric reference, known as
3.11 collector, concentrating: Solar collector that
the WRR.
uses reflectors, lenses or other optical elements to
redirect and concentrate the solar radiation passing
through the aperture onto an absorber of which the
3 Definitions
surface area may be smaller than the aperture area.
For the purposes of this part of IS0 9459, the follow-
3.12 collector,, flat-plate: Non-concentrating solar
ing definitions apply.
collector in which the absorbing surface is essentially
planar.
3.1 absorber: That part of a collector that receives
radiant energy and transforms it into thermal energy.
3.13 collector loop: Continuous path followed by
3.2 accuracy: Ability of an instrument to indicate the
the primary heat transfer fluid in a solar energy sys-
true value of the measured physical quantity.
tem.
3.3 ambient air: Air in the space (either indoors or
3.14 collector loop heater: Heater installed within
outdoors) surrounding the thermal energy storage
the collector loop when testing the solar domestic
device or solar collectors, whichever is applicable.
water heating system with a non-irradiated array.
3.4 angle of incidence (of direct solar radiation):
3.45 collector tilt angle: Lower angle between the
Angle between the solar radiation beam and the
aperture plane of a solar collector and the horizontal
outward-drawn normal from the plane considered.
plane.
3.5 aperture area: Of a solar thermal collector,
3.16 control: Device for regulation of the solar
maximum projected area through which the uncon-
thermal system or component in normal operation;
centrated solar radiation is admitted.
can be manual or automatic.
NOTE 1 For concentrating collectors, the gross aperture
area includes
...