Remote indoor air temperature monitoring using infrared technology

Traditional sensor measurements require room entry, which disrupts occupants and increases costs. To overcome these drawbacks, a non-intrusive method was proposed to estimate the indoor air temperature through exterior window surface measurements using infrared technology. However, this method has only been validated in a controlled first-floor laboratory setting and cannot be directly applied to actual multistorey residential buildings. In this study, a numerical model of a window glass with a screen was established. Field experiments were conducted in a commercial residential building under three distinct conditions: heating, natural ventilation, and cooling. The established numerical model was validated using the measured data, and the effects of the capture time and distance on the indoor air temperature estimation were examined. The results showed that the optimal capture time of infrared technology was between 18:00 and 3:00, and the optimal capture distances of the second and third floors were 13 m and 19 m. Moreover, the proposed method of capturing infrared images of exterior windows could reflect the vertical stratification phenomenon of the indoor air temperature. This study provides technical guidance for remote estimation of indoor air temperatures in complex scenarios using infrared technology.