In-situ evaluation of non-destructive methods for assessing the insulation performance of heavyweight building envelopes

Accurate evaluation of thermal transmittance is critical for assessing the energy performance of building envelopes, particularly in high-performance, heavyweight structures. In South Korea, where reinforced concrete buildings dominate the urban landscape, in-situ and non-destructive methods provide practical advantages by overcoming access limitations and avoiding invasive procedures. This study assessed the field applicability and accuracy of three representative non-destructive methods: the heat flow meter (HFM) method (ISO 9869-1), the Infrared Thermography method (IRT-1) based on ISO 9869-2, and an exterior-side infrared method (IRT-2) using the Jürges equation. These methods were applied to walls and windows of a newly constructed, highly insulated heavyweight building. HFM demonstrated high accuracy but required extended stabilization, especially for walls. IRT-1 produced reasonable results for lightweight components, such as windows, with deviations of 6.5% (interior) and 14.4% (exterior), but was unsuitable for heavyweight walls. IRT-2 showed strong agreement with wall measurements under low-wind conditions, with only a 3.8% deviation from the design value, but was ineffective for windows due to their lightweight composition, heterogeneous materials, and rapid surface temperature changes. Windows are more influenced by convection and conduction, complicating stable and accurate thermal transmittance measurements using this method. These findings highlight the importance of selecting appropriate methods based on material properties and environmental conditions. They also emphasize the potential of integrating thermographic techniques with remote sensing technologies, such as UAV-based infrared imaging, to enable efficient and scalable thermal diagnostics of building envelopes.