Time-lapse thermography for building defect detection: Fid-Bau Portal

Time-lapse thermography for building defect detection

Fox, Matthew / Coley, David / Goodhew, Steve / De Wilde, Pieter

Highlights • A time-lapse thermography methodology is tested over two case study dwellings. • Comparisons with traditional thermography are made to help overcome limitations. • The practicalities of a time-lapse methodology are identified and overcome. • Construction systems dictate the time-lapse temporal resolution. • Monitoring the evolution of thermal patters aided in defect characterisation.

Abstract Building thermography traditionally captures the thermal condition of building fabric at one single point in time, rather than changes in state over a sustained period. Buildings, materials and the environment are, however, rarely in a thermal equilibrium, which therefore risks the misinterpretation of building defects by employing this standard methodology. This paper tests the premise that time-lapse thermography can better capture building defects and dynamic thermal behaviour. Results investigating the temporal resolution required for time-lapse thermography over two case study houses found that under typical conditions small temperature differences (approximately 0.2K) between thermal areas could be expected for 30-min image intervals. Results also demonstrate that thermal patterns vary significantly from day-to-day, with a 2.0K surface temperature difference experienced from one day to the next. Temporal resolutions needed adjusting for different types of construction. Time-lapse experiments raised practical limitations for the methodology that included problems with the distance to target and foreground obstructions. At the same time, these experiments show that time-lapse thermography could greatly improve our understanding of building transient behaviour and possible building defects. Time-lapse thermography also enables enhanced differentiation between environmental conditions (such as clear sky reflections), actual behaviour and construction defects, thereby mitigating the risk of misinterpretation.