ISO 9869-2:2018

INTERNATIONAL ISO
STANDARD 9869-2
First edition
2018-08
Thermal insulation — Building
elements — In-situ measurement of
thermal resistance and thermal
transmittance —
Part 2:
Infrared method for frame structure
dwelling
Isolation thermique — Éléments de construction — Mesurage in
situ de la résistance thermique et du coefficient de transmission
thermique —
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and units . 2
5 Principle . 3
6 Requirements for apparatus . 4
6.1 General . 4
6.2 Infrared camera . 5
6.3 Heat transfer coefficient sensor . 6
6.4 ET sensor . 6
6.5 Thermocouple . 6
6.6 Data logger . . 6
7 Measurement method . 6
7.1 Building . 6
7.2 Location of the measured area . 6
7.3 Measurement conditions . . 7
7.4 Measurement of heat transfer coefficient . . 7
7.5 Measurement of environmental temperature . 7
7.6 Surface temperature distribution of building elements . 8
7.7 Measurement time and measurement interval . 8
7.8 Measurement terms. 8
7.9 Measurement period. 9
8 Calculations. 9
8.1 Heat transfer area . 9
8.2 Calculation of heat flow rate. 9
8.3 Calculation of thermal transmittance.10
9 Measurement accuracy .10
10 Test reports .10
Annex A (informative) Measurement principle .12
Annex B (informative) Calculation of environmental temperature, structure of ET sensor .16
Annex C (informative) Structure and calibration of heat transfer coefficient sensor .19
Annex D (informative) Uncertainty analysis .24
Annex E (informative) The calculation example of uncertainty analysis .27
Bibliography .31
Foreword
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This document was prepared by ISO/TC 163, Thermal performance and energy use in the built
environment, SC 1, Test and measurement methods.
A list of all parts in the ISO 9869 series can be found on the ISO website.
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iv © ISO 2018 – All rights reserved

Introduction
The ISO 9869 series describes the in-situ measurement of the thermal transmission properties of plane
building components, primarily consisting of opaque layers perpendicular to the heat flow and having
no significant lateral heat flow. The thermal transmittance of a building element (U-value) is defined in
ISO 7345 as the “Heat flow rate in the steady state condition divided by area and by the temperature
difference between the surroundings on each side of a system”. Since steady state conditions are never
encountered on a site in practice, such a simple measurement is not possible and thereby some statistical
methods are introduced. One of the simplest methods is using the mean values over a sufficiently long
period of time. The required time for observation for reliable measurements depends on the thermal
properties of the building components and the natures of the temperature difference between the
surroundings on each side of them.
ISO 9869-1 describes the method which is used to estimate the thermal steady-state properties of a
building element from heat flow meter (HFM) measurements through plane building components.
Annex B describes the statistical methods of simple mean and the sophisticated method of dynamic
analysis method for steady state properties. This document, describes the calculation method for the
density of heat flow rate through both the evaluation of the internal surface thermal resistance and
the measuring of the temperature difference between the indoor surface temperature of the building
element and the indoor environmental temperature using an infrared camera (thermo-viewer). It
also describes the statistical methods of simple mean with less observing duration considering night
observation and building components with light heat capacity.
This document provides a preliminary and handy measuring method for the in-situ measurement of the
thermal transmission properties of plane building components and thereby the further simplifications
are applied compared with the method described in ISO 9869-1. The method described in this document
is expected as a method of a handy diagnostic method of the thermal transmission properties of plane
building components with light heat capacity such as those in frame structure dwelling.
The thermal performance of a part of the building element is evaluated by obtaining the heat absorption
(heat penetration) at the part of the indoor surface by multiplying the indoor total heat transfer
coefficient of the part surface by the difference between the part indoor surface temperature and the
indoor environmental temperature. The thermal transmittance (U-value) of the building components
for steady state condition can be obtained with the averages of the observed values over the certain
period of time.
The indoor surface temperature distribution of the building component is measured using an IR camera.
The indoor environmental temperature is measured by installing the environmental temperature
sensor (ET sensor) on the surface of the building component, and the indoor total heat transfer
coefficient of the surface of the building component is measured using a heat transfer coefficient sensor.
Even the indoor measurement is intended to be carried on with less influence of solar radiation so the
standard can be used on building elements on which indoor sides are not exposed to direct sunlight
through adjacent windows.
INTERNATIONAL STANDARD ISO 9869-2:2018(E)
Thermal insulation — Building elements — In-situ
measurement of thermal resistance and thermal
transmittance —
Part 2:
Infrared method for frame structure dwelling
1 Scope
This document describes the infrared method for measuring the thermal resistance and thermal
transmittance of opaque building elements on existing buildings when observing high emissivity diffuse
surface using an infrared (IR) camera. This document demonstrates a screening test by quantitative
evaluation to identify the thermal performance defect area of building ele
...