A non destructive method for diagnosis of insulated building walls using infrared thermography in real situation

摘要

In order to provide a method to control conformity of insulation of buildings after restoration, Protomeres project was launched under Prebat 2005 program. This work deals with the development of an experimental protocol for the diagnostic of multi-layered insulated building walls. In a previous study, a test bench was set up in order to measure front and back side temperatures of standard panels compounded of lcm of plaster and various thicknesses of polystyrene. The panels considered have insulation thicknesses of 2, 6 and 10cm. In the present work, the panels are fixed on walls in laboratory to test real situations in constructions. The front side is painted in standardized black color and heated by two halogen lamps of 500W. A CEDIP Jade Long wave infrared camera and thermocouples are used to carry out temperature measurements during an exposure time and subsequent cooling. In a second time, a one dimensional model based on thermal quadruples and Laplace transforms was developed under Matlab environment. This model simulates a three-layered wall with a blade of air between polystyrene and concrete. Finally, a method of identification of physical parameters is implemented by performing least square minimization based on Levenberg-Marquardt method. The experimental measurements are compared to theoretical results and by minimization we obtain thermal conductivity and diffusivity as well as thickness of the two layers.