열화상측정법을 이용한 경량 목조 외벽체의 현장 열관류율 추정 정확도에 대한 측정시간의 영향 분석

Infrared thermography (IRT) method has been proposed as a non-destructive method for estimating in-situ thermal transmittance (U-value) of exterior walls due to its ability to inspect relatively large areas in real time. Because the IRT method is based on heat transfer assuming the steady state condition, many researchers have investigated measurement conditions that can improve the accuracy of in-situ U-value estimation. They have reported that to increase the reliability of the results, IRT measurements should be taken before sunrise, when temperature differences are large and the effects of solar irradiation are minimized. However, the effects of time-specific environmental conditions on the accuracy of IRT methods have rarely been examined. In this study, we analyzed the effect of environmental conditions on the accuracy of in-situ U-value estimation by performing a descriptive statistics using boxplot on subcases separated by 3-hour intervals from data measured by the IRT method over 14 days. The data were measured from January 25, 2023 to February 7, 2023 on a north-facing lightweight wooden exterior wall with a theoretical U-value of 0.185 W/㎡·K. The findings show that the accuracy of U-value estimation using the IRT method can vary significantly depending on the influence of environmental conditions.