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U-Value KIT: Instruction Manual
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green
TEG
AG
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8153 Rümlang, Switzerland
T: +41 44 515 09 15
greenTEG.com
Appendix A: U-Value software introduction
The appendix highlights key elements of the ISO 9869-1:2014 on which the data analysis of the software is based.
Even though the software is capable of analysing the measurement data, it is the user of the system who has to
ensure applicability of the ISO test conditions to measurement data.
Requirements according ISO 9869-1:2014
The standard ISO 9869-1:2014 states in section 6 how a measurement apparatus must be installed for proper
measurement and in section 7 how the measurement data must be analysed.
The ISO standard highlights the following important points for the
installation
:
•
Heat flux meters (HFM) and temperature sensors shall be mounted at a
location
that is representative
of the whole element (previous inspection using thermography cameras are mentioned).
•
HFMs shall
not
be
o
installed close to
thermal bridges
,
cracks
or similar sources of error
o
under direct influence of a
heating or of a cooling device
or under the
draught of a fan
•
The outer surface of the element should be
protected
from
o
Rain
o
Snow
o
Direct solar radiation
•
Protection of the outer surface may be achieved through
artificial screening
.
•
Data acquisition intervals should be less than 30min.
The
analysis
of the measurement data is separated into two methods. The first analysis method (the average
method) is introduced in section 7.1 of the standard. It is the method used in the current software. The average
method is valid if certain conditions are met:
•
The
heat content of the element is the same at the beginning and at the end
of a measurement
(same temperatures and moisture distribution)
•
The HFM is
not
exposed
to direct solar radiation
.
•
False results might be obtained if the
external face
of the element
is exposed to solar radiation
•
The thermal conductance of the element is constant during the test
If the above conditions are not met, misleading results can be obtained. It is the responsibility of the user to
ensure that the conditions are met.
Data analysis (average method) for heavier elements with a specific heat per square meter greater than 20kJ/(m
2
K)
according to section 7.1 shall be carried out over a
period of integer multiple of 24h
.
The measurement shall be ended only when
the conditions are fulfilled
as follows:
1.
Duration of the measurement
> 72h
2.
R-value obtained at the end of the test does not deviate more than 5% from the value obtained 24h
before (dR24)
3.
The R-value obtained during the first 2/3 of the overall measurement period (which needs to be an
integer of 24h, too) does not deviate more than 5% from the values obtained during the last 2/3 of the
overall measurement period (also an integer multiple from 24h).
4.
The change in heat stored in the wall is <= 5% of the heat passing through the wall
While test conditions 1
–
3 are validated by
greenTEG’s
software, the condition 4 is not tested. greenTEG
’
s
measurement system does not allow measurement of heat storage changes of the wall.
