Experimental investigation of acoustic airtightness measurement and UAV-based quantitative infrared thermography for building energy performance assessment

In existing buildings, knowledge about the thermal envelope, its physical parameters, and possible hidden defects is often insufficient. This issue contributes to the performance gap between modeled and actual energy efficiency of existing buildings. Furthermore, reliable data about the existing structure is essential for cost-efficient retrofit strategies to reduce operational costs and carbon emissions. As a consequence, improving on-site measurements could offer new strategies to address the performance issues and promote efficiency measures. In an experimental investigation, this study explores two innovative methods applied to an exemplary building complex: acoustic air leakage detection and quantitative UAV-based infrared thermography. For acoustic leakage detection, the method effectively discerns the airtightness quality of large buildings but lacks sufficient automation and accuracy for robust quantitative evaluation. The drone-based thermography method featuring repeated coverage of a building over the course of a night holds promise for large-scale thermal assessment, but faces high equipment requirements, difficulties in precise image positioning, and challenges in integrating thermal data into 3D building models. Moreover, environmental factors such as wind, temperature gradients, and drone-induced turbulence introduce uncertainties that complicate reliable quantification. These challenges underscore the need for improved calibration procedures, advanced processing algorithms, and integration with dynamic building performance simulation. Despite these obstacles, the methods demonstrate promise for large-scale applications, with potential to automate and enhance energy performance assessments in future research.