Requirements according ISO 9869-1:2014

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 analyzing the measurement data, it is the user of the system who has to ensure applicability of the ISO test conditions to measurement data. The most important aspects for an ISO 9869 compliant U-value measurement are listed. For more detailed information please refer to the complete ISO 9869 documentation.

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 analyzed.

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
  • installed close to thermal bridges, cracks or similar sources of error
  • 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
  • Rain
  • Snow
  • Direct sola radiation
• Protection of the outer surface maybe 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/(m2K) according to section 7.1 shall be carried out over a period of integer multiple of 24h.