평균법에 의한 현장 측정 열저항의 실내·외 온도차변동성에 따른 수렴조건 분석

This study analyzes the convergence characteristics of in-situ thermal resistance (R-value) obtained by the average method according to the criteria of ISO 9869-1. In-situ measurement of thermal resistance was conducted for an opaque exterior wall of an old apartment constructed in 1990 for three weeks during the winter. Unlike previous analyses on the effect of difference in the indoor and outdoor temperature, this paper focuses on the changes of that variable over a time period. This study shows that the criteria for determining the end of measurement are very strict, mainly because of the third convergence condition, which compares the deviation of two values derived from the initial and last periods. To achieve the third convergence condition, indoor and outdoor temperature differences should be kept constant throughout the test between the initial and last duration. Thus, it was selected a period in which the indoor and outdoor temperature difference is maintained constant among the total measurement period. this period easily satisfies the convergence conditions according to the ISO 9869-1.