Analysis of Convergence Characteristics of Average Method Regulated by ISO 9869-1 for Evaluating In Situ Thermal Resistance and Thermal Transmittance of Opaque Exterior Walls

Doo Sung Choi and Myeong Jin Ko
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Doo Sung Choi: Department of Architectural Engineering, Chungwoon University, Incheon 22100, Korea
Myeong Jin Ko: Department of Building System Technology, Daelim University College, Anyang 13916, Korea

Energies, 2019, vol. 12, issue 10, 1-18

Abstract: In the last few decades, an average method which is regulated by ISO 9869-1 has been used to evaluate the in situ thermal transmittance ( U -value) and thermal resistance ( R -value) of building envelopes obtained from onsite measurements and to verify the validity of newly proposed methods. Nevertheless, only a few studies have investigated the test duration required to obtain reliable results using this method and the convergence characteristics of the results. This study aims to evaluate the convergence characteristics of the in situ values analyzed using the average method. The criteria for determining convergence (i.e., end of the test) using the average method are very strict, mainly because of the third condition, which compares the deviation of two values derived from the first and last periods of the same duration. To shorten the test duration, environmental variables should be kept constant throughout the test or an appropriate period should be selected. The convergence of the in situ U -value and R -value is affected more by the length of the test duration than by the temperature difference if the test environment meets literature-recommended conditions. Furthermore, there is no difference between the use of the U -value and R -value in determining the end of the test.

Keywords: thermal resistance; thermal transmittance; heat flow meter method; average method; convergence characteristics; opaque exterior wall (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (8)

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