Publications / 2024 Proceedings of the 41st ISARC, Lille, France
Maintaining energy performance of ageing building stock has become a global priority towards a more environmentally sustainable future in the age of climate change. Unmanned Aerial Vehicle (UAV) equipped with thermal camera is increasingly used for building inspection. However, scant attention has been paid to the satisfactory image acquisition strategy for a rigorous building energy audit. To narrow this research gap, this paper undertakes a comparative analysis of the impact of three primary features of UAV thermal image collection strategies on accurate thermal anomaly evaluation. Firstly, a laboratory-scale building featuring artificial thermal anomalies was developed and constructed. Then, UAV thermal images were collected under various inspection conditions, examining features including temperature difference between interior and exterior environments, ground sampling distance (GSD), and UAV oblique angle. GSD herein refers to the GSD of the collected UAV thermal images. The collected thermal images underwent a comprehensive analysis and comparison to understand the influence of the three features. The results suggest that: thermal images collected with highest interior and exterior temperature difference are recommended for identifying all potential thermal anomalies; a GSD of within 5 mm is recommended to ensure the visibility of thermal damages in the collected thermal images; a multi-scale thermal image collection strategy is recommended for an efficient and accurate evaluation of thermal anomalies, especially minor defects; a UAV oblique angle within 30° is recommended to ensure a high image contrast between damaged and undamaged areas on the inspected façade.