Using an inverse method to evaluate envelope thermal properties

The objective of this work is to present an inverse method solving the transient heat-transfer problem in walls aiming to estimate its thermal properties. The procedure uses a finite difference numerical scheme, simulated in the environment SIMSPARK that is non object oriented and allows solving highly non linear problems. A method aiming to estimate building envelope thermal characteristics is elaborated knowing experimental in situ measurements. The results present a good agreement between the forward and the inverse method respectively on a high-weight concrete and then on a Phase Change Material wall. Extrapolation of the method on a building model is realized to find the required air ventilation rate for a summer and a winter climate. Finally, the procedure is applied on a multilayered wall to estimate the U-value using real experimental data. The study shows clearly the possibility to identify a modification occurred on the wall composition and the moment at which this modification happens. The method can be used for different applications and provides a good accuracy on the results.